Court Opinion

ID: 9362170
Source: CourtListenerOpinion
Date Created: 2023-01-13 07:05:54.960503+00
Date Added: 2024-06-11T16:57:31.698763
License: Public Domain

Pee Curiam :
This case comes before the court on exceptions by the parties to the recommended decision filed February 27,1975, by former Trial Judge Hal D. Cooper (since resigned), pursuant to Eule 134(h), having been considered on the briefs and oral argument of counsel. Since the court agrees with the trial judge’s recommended decision, as hereinafter set forth, it hereby affirms and adopts the same as the basis for its judgment in this case. It is therefore concluded: (a) that claims re Patent No. 3,419,900 (claims 4 and 7), *876Patent No. 3,276,909 (claim 9) and Patent No. 3,436,270 (claims 1, 2, 3, 5-8, 10, 16 and 17) are valid and infringed and defendant 'has no license thereunder; (b) claims re Patent No. 3,436,270 (claim 19), Patent No. 3,553,024 (claims 1, 3,4, 6 and 11) and Patent No. 3,378,406 (claims 1,3, 8 and 9) are invalid; (e) claims 12,15 land 16 of Patent No. 3,438,815 are not infringed by defendant; and (d) defendant is licensed under claims 1, 2, 3, 8 and 9 of Patent No. 3,531,327. Accordingly, plaintiff is entitled to recover reasonable and entire compensation in accordance with this opinion and judgment is entered for plaintiff theref or, the extent of which will be determined in further proceedings pursuant to Buie 131.
OPINION OP TRIAL JUDGE
Cooper, Trial Judge:
Contending that seven of its patents have been infringed, plaintiff seeks reasonable and entire compensation under 28 U.S.C. § 1498 for defendant’s procurement of a metal/air battery designated the BB-626 ( )/U. Defendant presents its usual array of defenses, attacking validity of each patent on a multiplicity of grounds, asserting there is no infringement of most of the patents, and ¡alleging a license running to defendant under all of the patents.
For the reasons hereinafter stated, it is concluded that the claims at issue in patents Nos. 3,276,909, 3,419,900, and 3,436,270 (except claim 19) are valid and infringed, and that defendant has no license thereunder. It is further concluded that the claims at issue in patents Nos. 3,553,024 and 3,378,406, and claim 19 in No. 3,436,270 are invalid; that patent No. 3,438,815 is not infringed; and that patent No. 3,531,327 is subject to a license to defendant.
The subject matter in this case pertains to batteries or, stated in more technical terms, electrochemical devices for producing electrical energy through chemical processes. These devices employ a pair of electrodes (an anode and a cathode), a fuel to be consumed, and an electrolyte as essential components in the production of electrical energy. In some batteries, flashlight batteries being but one example, all reactants, including the fuel which is a metal that is a *877part of one of the electrodes, are contained in the battery package. In other more sophisticated types of batteries (sometimes called fuel cells),1 the reactants, including the fuel which may be a gas such as hydrogen, are supplied continuously from an esternal source. In either case, it is the chemical process of fuel oxidation that produces the electrons for the current in 'an external circuit.
The fuel cell type of battery is usually distinguished from other batteries in that the fuel cell electrode is merely a situs for the chemical reaction and is not consumed by that reaction. As a result, the useful life of a fuel cell is not normally measured in terms of its electrode life. The more conventional batteries, on the other hand, are designed to have one or both of the electrodes take 'an active part in the reaction so that at least one of the electrodes is consumed by the reaction. When the electrode is consumed, either the battery is thrown away or it is electrically recharged. Historically, throwaway batteries have befen known as “primary” batteries while the rechargeable type has been designated a “secondary” battery.
The metal/air batteries accused to infringe are a hybrid. As with conventional batteries, the anode of a metal/air battery contains the fuel and is consumed by the chemical reaction. The cathode, however, is not consumable and, as in a fuel cell, the reactant, oxygen, is supplied from the ambient air on a continuous basis. Further, although the battery is not electrically rechargeable and, hence, is of the primary type, it is designed for rapid mechanical replacement of the consumed electrode so it is considered to be mechamcally rechargeable.
Of the patents in suit, the ’909, ’900, ’815, and ’024 patents are concerned with electrode structures. The ’270, ’406, and ’327 patents are directed to a metal/air battery configuration and the mechanical rechargealbility of that battery.

*878
Elmore and Tcrnner Patent No. 3,419,900

This patent discloses tan electrode structure comprising a catalytic layer made 'from a uniform admixture of a fluorocarbon polymer and a catalytic metal powder. The fluorocarbon is preferably polytetrafluoroethylene (sometimes referred to either tas PTFE or by du Pout’s trademark Teflon). This mixture is carried by a suitable current collector such as a silver screen or a porous carbon block with the electrolyte being on one side of the catalytic layer and a gaseous reactant on the other.
'Claim 4, the only independent claim asserted to be infringed,2 is as follows:
An electrochemical cell for the direct generation of electrical energy comprising an anode, a cathode, and an electrolyte, said electrochemical cell being constructed and 'arranged to provide a space between said anode and cathode and said space containing said electrolyte, at least one of said 'anode and cathode being a non-consumable, gias-consuming electrode comprising a catalytic layer containing a substantially uniform admixture of metal containing electrocatalyst particles and a fluorocarbon polymer, said catalytic layer being exposed to the electrolyte of the cell and having a porosity sufficient to permit diffusion of gases into said catalytic layer.
All of the elements of the claim are concededly old except for tire use of “a substantially uniform admixture of metal containing electrocatalyst particles and a fluorocarbon polymer” as a catalytic layer. The evidence is that Elmore and Tanner were the first to use this combination of materials in an electrode for an electrochemical cell.
At the outset, defendant contends that the specification is defective within the meaning of 35 U.S.C. § 112 because it does not specify the critical ratio of the catalyst to the fluorocarbon. Although defendant is correct that precise recipes are not set out in the specification, a patent is directed to those skilled in the art and need only be in sufficient detail to enable them to- practice the invention. Trio Process Corp. v. L. Goldstein's Sons, 461 F. 2d 66, 74 (3d Cir. 1972), cert. denied, 409 U.S. 997; Gray Co. v. Spee-Flo Manufacturing *879Corp., 361 F. 2d 489, 493 (5th. Cir. 1966). That requirement is satisfied here for it is clear from the evidence that a very wide range of ratios may be employed, depending on the particular desired use. The basic controlling consideration, as those in the art would readily recognize, is that 'an excess of polymer will adversely affect conductivity. As to specific ratios, the testimony of plaintiff’s witnesses, Dr. Frysinger 'and Dr. Giner, and defendant’s witnesses, Dr. Weissman and Mr. Moran, establishes that one of ordinary skill in the art would have no difficulty at all in selecting workable proportions in light of the patent disclosure.
Defendant next contends that the combination of claim 4 is anticipated by Niedrach et al Patent No. 3,297,484. This defense is premised on the contention that claim 4 is not entitled to the original filing date of March 4, 1960, but is entitled only to the December 22, 1966 date on which a continuation-in-part application was filed. Yet, each and every term of claim 4 is supported by, and was plainly disclosed in, the original application filed in 1960. Also from the time the first application was filed, Elmore and Tanner consistently presented claims to a new electrode composition consisting of a mixture of fluorocarbon and catalyst particles. In light of these facts, claim 4 is entitled to the filing date of March 4, 1960. Pursche v. Atlas Scraper & Engineering Co., 300 F. 2d 467 (9th Cir. 1961), cert. denied, 371 U.S. 911 (1962); Kollsman v. Ladd, 226 F. Supp. 186 (D. D.C. 1964). Since the Niedrach patent has a filing date of May 8, 1961, it is not a reference against this claim.3
The principal defense asserted by defendant is that of obviousness under 35 U.S.C. § 103. This defense requires consideration of the scope and content of the prior art in 1958 when Elmore and Tanner made their invention, and a determination of whether the differences between that art and the claims in issue would have been obvious to one of ordinary skill in the art. Graham v. John Deere Co., 383 U.S. 1 (1966).
Defendant relies mainly on Berl Patent No. 2,275,281, Winckler et al Patent No. 2,641,623, Witherspoon et al pub*880lication entitled “The Oxygen Electrode,”4 and the argument that the use of Teflon was a mere substitution of one plastic for another.
In considering this defense, it is necessary to place the prior 'art in context. Prior to 1958, a major problem with air- or gas-breathing electrodes had been the need to develop an electrode that would be permeable to the gas, but not so porous as to permit the electrolyte to flood the pores of the electrode. In the sophisticated fuel cell, a partial solution was the use of a biporous electrode structure and balanced gas pressures. In the more common variety of battery, various wet-proofing techniques were employed to control electrode flooding. Of particular interest are the approaches described in the Berl and Winclder patents, as well as in Witherspoon, wherein a binder material having hydrophobic properties is dissolved and the solution is combined with particles of a suitable material such as activated carbon. The generally accepted view is that the prior art approach, using, for example, ethyl cellulose, resulted in the electrode particles being at least partially coated with the plastic material. This material inhibits wetting of the electrode particles by the electrolyte and tends to form a barrier beyond which the electrolyte cannot pass. Since gas does not pass through liquid in significant quantities, this barrier then defines a line along which the chemical interaction among the three phases, gas, liquid, and solid, takes place.
The differences between the claimed electrode and that prior art, in terms of structure, reside both in the use of !a fluorocarbon as the binder material and in mixing particles of the fluorocarbon with particles of catalyst instead of coating the catalytic particles with a solution of the plastic binder material as is the case with Berl and WineMer.
The differences between the claimed electrode and the prior art, in terms of functional operation, were the subject of extended testimony at trial. Dr. Giner’s “flooded agglomerate” theory (finding 12) suggests that the claimed combination would allow the electrolyte to wet all of the catalyst particles, while the Teflon particles would provide a path *881for the air to permeate the catalytic layer. This would permit •the desired three-phase reaction to occur throughout the volume of catalytic material. Dr. Frysinger explained this as a “volume reaction” in which the entire volume of catalyst is utilized, as opposed to the “line reaction” of the prior art such as Berl and Winclder where the reaction takes place along a line defined by the gas-liquid interface.5 Defendant's expert Dr. Gilman did not contest Dr. Giner’s theory, but emphasized that it was only a theory; however, that theory has received acceptance in the industry and no opposing theories have been advanced.
The differences between the claimed electrode and the prior art, in terms of result, are not seriously in dispute. Teflon-bonded electrodes have demonstrated clear superiority in areas of energy and power density. Defendant’s Dr. Gilman summed it up when he testified that everyone has gotten on the “bandwagon” of Teflon-bonded catalysts. This has included companies such as General Electric, American Cyan-amid, and Pratt & Whitney.
Based on these differences in structure, function, and result, defendant’s contention that the use of Teflon is a mere substitution of materials in the Berl and Wdnckler electrodes cannot be accepted. It ignores the fact that not only is the material not suggested by any prior art but that neither Berl nor Wdnckler suggests using binder particles in a mixture with catalyst particles. Thus, not only is a different material used, it is being used in a different form to produce a different structure, with significantly improved and unexpected results. Hence, more than a mere substitution is •involved. Carbide & Carbon Chemicals Corp. v. Coe, 102 F. 2d 236, 241 (D.C. Cir. 1938); Allen Filter Co. v. Star Metal Manufacturing Co., 40 F. 2d 252 (3d Cir. 1930), cert. denied, 282 U.S. 848.
Defendant also contends that Teflon-bonded electrodes were simultaneously developed by a number of individuals and that this is further indicative of its obviousness. While that factor is sometimes considered as an indicia of obviousness, see, e.g., Felburn v. New York Central R.R., 350 F. 2d *882416, 425-26 (6th Cir. 1965), cert. denied, 383 U.S. 935 (1966), the facts do not support such a conclusion here. Elmore and Tanner made their invention in mid-1958, well over a year before the work of anyone else in the field. The bulk of the publications on which defendant relies to establish the alleged simultaneous invention bear dates subsequent to Elmore’s public disclosure of their work in May 1960. Moreover, Elmore and Tanner have been recognized by those in the field as being the first to work with Teflon-bonded electrodes.
In the final analysis, the “before and after” actions and judgments of those in the field, Safety Car Heating & Lighting Co. v. General Electric Co., 155 F. 2d 937, 939 (2d Cir. 1946), are the most persuasive evidence that the combination of claim 4 was an unobvious development. Before the invention, work was being done with plastic materials as binders for electrodes. Although Teflon was available, no one had suggested using that material, despite its well-known hydrophobic properties. After Teflon-bonded electrodes became known, virtually the entire industry shifted to it, even though no one understood why the electrode was so superior to the prior art. Since then, a great deal of research has been devoted to this electrode but, even now, only theories have been developed to explain its superior performance.
Under these circumstances, it is concluded that claims 4 and 7 are valid.
As to infringement, the BB-626 ( ) /U is plainly an electrochemical cell for the direct generation of electrical energy. Defendant has stipulated that the cathode is a uniform admixture of Teflon and a catalyst. A case of infringement of claims 4 and 7 has been established.
Defendant’s contention that 28 U.S.'C. § 1498 bars this suit because Dr. Tanner was an employee of the United States at the time he executed the continuation-in-part application is without merit. Dr. Tanner was neither employed by nor in the service of defendant either when the invention of claims 4 and 7 was made in 1958 or when the original application was filed in 1960. Since the claims are entitled to the 1960. filing date, his subsequent employment history is irrelevant and the bar expressed in 28 U.S.C. § 1498 is inapplicable.
*883Finally, defendant contends that it is entitled to an “implied” license under this patent, pointing to a series of contracts commencing in March. 1966 between the parties for the militarization and procurement of plaintiff’s zinc/air battery, and to plaintiff’s acquisition of the Elmore and Tanner patent application in June 1966. These facts, 'however, are insufficient to award defendant a license.
The Teflon-bonded electrodes of claims 4 and 7 were neither first conceived nor reduced to practice under any federally funded project, or under any contract with defendant. The work of Elmore and Tanner was financed by the Kettering Foundation, and plaintiff, which 'had been working with Teflon-bonded electrodes prior to 1966, had incorporated that type of electrode in its own privately funded zinc/air battery program prior to all of the contracts on which defendant relies. Therefore, Teflon-bonded electrodes were never a “subject invention” under the patent rights clause of any of the contracts, and as defendant apparently concedes, it has no express license.6
In view of these facts, defendant’s reliance on the “close umbilical connection” doctrine of Mine Safety Appliance Co. v. United States, 176 Ct. Cl. 777, 364 F. 2d 385 (1966), is misplaced. In important aspects, the situation here is the reverse of that in Mine Safety. In that case, the court found that the contractor’s allegedly separate project was in fact obtaining benefits from the Government sponsored and financed project being carried on at the same time. In this case, the benefits flow the other way. While the batteries it procured from plaintiff incorporated the Teflon-bonded electrode technology of claims 4 and 7, defendant contributed nothing at all to that development. Moreover, through plaintiff’s unilateral action in acquiring the Elmore and Tanner application, any liability defendant may have had to the Kettering Foundation by reason of these contracts with plaintiff was eliminated, again at no cost to defendant. Having received those benefits without the expenditure of any federal *884funds, and 'having failed to demonstrate any umbilical relationship between the work of Elmore and Tanner in 1958 and the procurement of batteries in 1966, defendant is not entitled to 'a license under this patent.7

Moos Patent No. 3$76,909

This patent discloses an electrode consisting of <a polymeric film that serves as a backing or support for the catalytic layer. The patent suggests that either hydrophilic or hydrophobic polymers could be used, polytetrafluoroethylene being listed as one suitable polymer. If a hydrophilic material is selected, the patent specifies that it should be oriented so it is in contact with the electrolyte; if a hydrophobic material is used, the patent discloses it should be oriented so it is in contact with the gas.
Claim 9, the only claim at issue, provides:
A fuel cell for the generation of electrical energy directly from a fuel and oxidant comprising an electrolyte, at least one oxidizing electrode, at least one fuel electrode, said electrodes being in contact with said electrolyte, and means for providing fuel cell reactants to said electrodes, ate [sic] least one of said electrodes comprising a porous hydrophobic polymer matrix 'having a porous conductive catalytically activating metal layer in intimate contact with one surface, the said oaba-lytically activating metal layer being in contact with the electrolyte of the fuel cell.
The principal prior art on which defendant relies for its contention of obviousness is Williams Patent No. 3,116,170. That patent was also the principal prior art relied on by the Patent Office. It discloses a hydrophilic support for a catalytic layer oriented with the hydrophilic material in contact with the electrolyte. Claim 9 differs in that a hydrophobic material is specified and the orientation is the reverse of that shown in Williams.
In considering the unobviousness of these differences, Graham v. John Deere, supra, it is pertinent that Teflon-backed electrodes have now been widely 'adopted in the in*885dustry and are recognized as one of tbe most efficient electrodes known. In light of tbe greatly improved performance of this type of electrode, two factors are particularly significant on tbe obviousness issue. As explained more fully in finding 19, the orientation of the Moos electrode Was contrary to accepted practice in the art. This is evidence of nonob-viousness. United States v. Adams, 383 U.S. 39 (1966). Moreover, General Electric, in its extensive work in this same area, failed to adopt a similar orientation until over iy2 years after Moos, and then found the good performance of the electrode to be surprising. (Finding 20.) That too is an indication of nonobviousness. Jones Knitting Corp. v. Morgan, 361 F. 2d 451, 457-8 (3d Cir. 1966).
The most pertinent prior art being that already considered by the Patent Office, and in view of the foregoing facts, it is concluded that claim 9 is valid.
Defendant also contends that the patent is unenforceable because, in an affidavit submitted to the Patent Office to distinguish the claim from the Williams reference, the inventor Moos stated that he holds a doctoral degree when, as plaintiff now stipulates, he does not. It is, of course, well settled that misstatements of fact in representations to the Patent Office may render the patent unenforceable. Walker Process Equipment, Inc. v. Food Machinery & Chemical Corp., 382 U.S. 172 (1965). The general rule, however, is that the misrepresentation must be relevant and material to the deliberations of the Patent Office. Tate Engineering, Inc. v. United States, 201 Ct. Cl. 711, 477 F. 2d 1336 (1973); Henkels & McCoy, Inc. v. Elkin, 316 F. Supp. 303 (W.D. Pa. 1970), aff’d 455 F. 2d 936 (3d Cir. 1972). Here, the file wrapper history reveals that the purpose of the affidavit was to report the results of certain tests conducted in plaintiff’s laboratory. The file history further indicates that it was the substance of the test results set out in the affidavit, not the degrees held by the affiant, that resulted in the allowance of claim 9. 'Since there was no factual error in the 'affidavit as to the tests conducted or the results thereof, the misstatement regarding Moos’ educational background is deemed to be immaterial. Accordingly, the defense of unenforceability cannot be sustained.
*886Defendant also contends that claim 9 is not infringed. In large part, this is based on the assertion that la metal/air battery is not a “fuel cell.” However, the Patent Office has stipulated to the contrary (findings 4, 21), and the evidence is that those in the art recognize this type of battery as a hybrid, having features of both a classic fuel cell and a conventional battery. The ’909 patent is concerned with electrode structures 'and it is particularly in this area that those in the art have recognized the overlap between classic fuel cells and conventional batteries. Accordingly, the distinction defendant seeks to draw cannot be sustained.
Nor can the contention that the BB-626( )/U has no “means for providing fuel cell reactants” be accepted. The one reactant, air, is fed on a continuous basis through openings in the casing. The other reactant, zinc, is supplied on a batch basis each time an anode is replaced. While defendant is correct that the reactants in the embodiment disclosed in the specification are fed continuously, the claim language does not require this. Since a periodic batch replacement is clearly a means of supplying a reactant and since the particular means by which the reactants are fed was neither significant to the prosecution history nor to the invention itself, plaintiff is not limited to the specific mode disclosed. A case of infringement has been made out.
Finally, defendant contends it has an “implied” license under this patent, relying principally on a Navy contract it had with plaintiff involving work in the area of fuel cells.8 Although that contract did contain a patent rights clause and was still open at the time Moos made his invention, the facts clearly show that the electrode was neither conceived nor reduced to practice in the performance of work called for or required under that contract. Moos’ work was financed by in-house funds, and it did not pertain to any aspect of the particular work then being performed under that contract. Defendant has no license. Erie Resistor Corp. v. United States, 150 Ct. Cl. 490, 279 F. 2d 231 (1960).

*887
Giner Patent No. 3,438,815

This patent discloses an electrode which includes a micro-porous metal layer for controling bubble pressure, the pore size of the layer being about 1 to 50 microns in diameter.
Bach of 12, 15, and 16, the only claims in issue, calls for a “porous self-sustaining metal layer of uniform and controlled porosity,” this metal layer clearly referring to the micro-porous layer described in the specification. The accused battery has nothing of a similar nature. The current collector, specified by plaintiff as corresponding to the claimed metal layer, is a conventional expanded metal screen with openings far in excess of 50 microns. While it is porous and self-sustaining and, in a very loose sense, could be said to have a uniform and controlled porosity, it is clear that it is neither intended to perform the function of the micro-porous metal layer disclosed, nor in fact does so. Any effect it would have on bubble pressure would be incidental and entirely insignificant.
It is well settled that more than a literal response to the terms of the claims must be shown to make out a case of infringement. Westinghouse v. Boyden Power Brake Co., 170 U.S. 537, 568 (1898); Marvin Glass & Associates v. Sears Roebuck & Co., 448 F. 2d 60 (5th Cir. 1971); Autogiro Co. v. United States, 181 Ct. Cl. 55, 384 F. 2d 391 (1967), rehearing denied, 184 Ct. Cl. 801 (1968). Since the accused metal layer does not perform substantially the same function in substantially the same way for substantially the same purpose as the patented micro-porous metal layer, there is no infringement and, hence, there can be no liability under this patent. Dominion Magnesium Ltd. v. United States, 162 Ct. Cl. 240, 320 F. 2d 388 (1963) .9

Fishman Patent No. 3,553,024-

This patent discloses the same basic electrode structure as that in Moos Patent No. 3,276,909, differing only in the re*888quirement that the Teflon film is to be unsintered, i.e., it has not been subjected to temperatures of 327° C. or above.
The difficulty in finding anything unobvious in the claimed combination is insurmountable. In suggesting the use of Teflon, the ’909 patent does not distinguish between the sintered and unsintered types of films, but both types were available commercially in 1961 when the Moos p'atent application was filed. What is clearly taught by Moos, however, is that the Teflon is to be oriented toward the gas, thus requiring diffusion of the gas through the Teflon. In light of that teaching, and the known generally impermeable nature of sintered Teflon (finding 28), it is concluded that it would have been obvious to anyone with any skill at all at the time Fish-man made his invention to try a permeable unsintered Teflon in the Moos arrangement. The substitution of an unsintered Teflon film in either of Examples 1 or 2 of the ’909 patent would inherently achieve the advantages and benefits claimed by Fishman since none of the process steps in either of those examples would subject the Teflon to temperatures in excess of 327° C. Unsintered Teflon being the logical choice to use, there is nothing patentable in Fishman’s selection of that material and claim 1 is deemed to define a combination that is obvious and invalid. Mills v. Watson, 223 F. 2d 335 (D.C. Cir. 1955).
Claims, 3, 4, 'and 6, dependent on claim 1, merely add details regarding the Teflon-bonded catalytic layer. Those details are disclosed in the ’900 patent and add nothing of patentable significance to the combination of claim 1 when presented in this patent. Claim 11, also dependent on claim 1, merely describes a zinc anode, something notoriously old in the battery field.
Claims 1,3,4,6, and 11 are invalid.

Oswin et al Patent No. 3,436,270

This patent discloses a metal/air battery having a gas permeable cathode of a particular design 'and a replaceable metal anode. The cathode, described as an envelope, forms a closely fitting pocket or enclosure for receiving the anode and the electrolyte. With this design, the cell is mechanically *889recharged merely by removing the expended anode from the envelope cathode and inserting a fresh anode.
Claims 1, 2, 8, 5-8,10,16, and 17 (all article claims), and claim 19 (a method claim), are asserted to be infringed. Defendant does not contest infringement and it is clear that each of the claims is infringed.
Defendant relies on 11 patents, in various combinations, in support of its contention that the article claims are obvious. (Finding 30.) Of these, only the Heise and Thompson patents disclose a mechanically rechargeable concept. Thompson is not otherwise pertinent, being merely a classic •type of railroad 'battery requiring a large volume of electrolyte. Heise does disclose a flat-cell configuration in which the anode is mechanically replaceable; however, the anode is spaced a substantial distance from the cathodes and this spacing, together with the rigid frame supporting the cathodes, both limits the intimate engagement of the anode, paste electrolyte, and cathode, and requires a substantial volume of the electrolyte. This same structural arrangement was basically employed by General Electric in its work in 1964.10
The contribution of Oswin and Chodosh lies in the close-fitting relationship of the replaceable anode and cathodes whereby a minimum volume of electrolyte is required and a high energy and power density cell is achieved. None of the prior art either discloses the same relationship or achieves comparable results. The importance of this relationship is confirmed both by the tests conducted by defendant (finding 32 (b)) and by the fact it was copied in the accused batteries; its unobviousness is revealed by the contemporaneous failure of General Electric and Yardney to arrive at a similar construction. LaSalle Street Press, Inc. v. McCormick & Henderson, Inc., 445 F. 2d 84, 93 (7th Cir. 1971).
*890Claim 111 is cast in rather broad language but is specifically limited to an “envelope cathode.” While language more specific in terms of structure would have been preferable, when construed in light of the specification and the prosecution history, it is apparent that this phrase was intended to describe a cathode structure that closely surrounds and encloses an anode. Clearly, the widely spaced cathodes and boxlike structures of Heise and General Electric are not an envelope in the sense intended by the patentees. Moreover, an interpretation of the claim which limits it to the close-fitting relationship disclosed in the specification is consistent with the principle that, where suspectible to more than one construction, that one will be adopted which will preserve to the patentee his actual invention. Tate Engineering, Inc. v. United States, supra; Dominion Magnesium Ltd. v. United States, supra. Here the construction most favorable in terms of preserving validity also coincides with the construction placed on the language by the patentees.
As properly construed, it is concluded that claim 1, and the claims dependent thereon, are valid and infringed.
Defendant’s contention that it obtained a license under these claims by reason of work under an Air Force contract performed by plaintiff is unsupported by the facts. The evidence, largely exhibits introduced by defendant, is that the envelope cathode and mechanical-recharge concept were conceived and reduced to practice by plaintiff prior to its entering into the contract. (Findings 34a-e.) Merely because plaintiff later used aspects of that technology in the performance of its contract does not give defendant any rights under the patent. Eastern Rotorcraft Corp. v. United States, 181 Ct. Cl. 299, 384 F. 2d 429 (1967). Defendant received the benefit of that technology without paying for its development; it does not also get a royalty-free license.
*891As to method claim 19,12 each of the recited method steps is inherent both in the Heise and the earlier G.E. work. The only distinction over the prior art lies in the envelope cathode structure set out in the claim. However, it is generally the' rule that patentability of a method claim must rest on the method steps recited, not on the structure used, unless that structure affects the method steps, a. delleR, patent claims § 372 (2d ed. 1971). In this case, it is apparent that the. claimed method steps are not affected by the claimed cathode structure since the very same method would be used with the box cathode of Heise.
There can be no doubt that the invention of the ’270 patent lies in the envelope cathode structure, not in the known method of recharging a battery by replacement of an anode.. That old method cannot be transformed into a patentably new one merely by using it to recharge a battery having a cathode not shown in the prior art. Pierce v. Muehleisen, 226 F. 2d 200 (9th Cir. 1955); Chenault v. Nebraska Farm Products, Inc., 138 F. Supp. 772 (D. Nebr. 1956). In short, claim 19. purports to define a new method and its validity must be assessed on the basis of the method steps described. Failing to define a method that is distinguishable from the prior-art methods, claim 19 is held to be invalid.

Rosansky Patent No. 3,378,406

This patent discloses a metal/air battery of the same type and construction as disclosed in the ’270 patent, Bosansky’s contribution being a system of specially designed spacers that separate the adjacent cells to provide access of air to the cathodes.
The use of spacers to provide a flow path for a gas between adjacent electrode surfaces is notoriously old and those in the battery art were, long prior to Kosansky’s work, familiar *892with the function of spacers in stacked electrodes. (Finding 36.) Plaintiff’s contention that the particular spacers designed by Bosansky control the growth of the cell can be given no weight since it is much narrower than the language of the claims. The claims are the measure of the invention and validity must be determined on the basis of what is claimed. Kemode Manufacturing Co. v. United States, 171 Ct. Cl. 698, 347 F. 2d 315 (1965); Chesterfield v. United States, 141 Ct. Cl. 838, 159 F. Supp. 371 (1958). Claim 113 merely calls for spacer elements; it does not relate those spacer elements to the cathode surfaces such that cell growth would foe controlled. It is not enough that the particular spacers shown in the drawings may be new and novel or perform a new function. Patent claims are required 'for the very purpose of forcing the patentee to insert in the claims those limitations and relationships regarded to be the invention. Strumskis v. United States, 200 Ct. Cl. 668, 474 F. 2d 623, cert. denied, 414 U.S. 1067 (1973); cf. Alma Motor Co. v. United States, 133 Ct. Cl. 59, 134 F. Supp. 641 (1955).
By casting claim 1 in overly broad language, the patentee has simply f ailed to provide a structural bridge between the desirable functional results said to be achieved and the mechanism by which those results are obtained. As broadly claimed, the combination of a plurality of cells with spacers *893therebetween does not distinguish from the G.E. battery or stacked cells of the Heise type.
While claim 1 is expressly limited to envelope cathodes, and defendant has not cited any prior art showing stacked envelope cathodes with spacers, that does not alter the obviousness conclusion. Plaintiff presents no argument that spacers, when used with envelope cathodes, achieve any different result or function any differently than when they are used with other kinds of cathodes. Most certainly, there is nothing in the claim to support such a conclusion. Accordingly, the question is simply whether the recitation of an “envelope cathode” in the combination of claim 1 is a sufficient basis on which to sustain the claim.
It is concluded that it is not. Only one patent can be granted for one invention. Miller v. Eagle Manufacturing Co., 151 U.S. 186 (1894); Tektronix, Inc. v. United States, 195 Ct. Cl. 53, 445 F. 2d 323 (1971). Envelope cathodes were the invention of Oswin and Chodosh, not Bosansky, and their 5270 patent discloses stacked envelope cathodes with spacers. Claim 2 of the ’270 patent sets out the same basic combination of a plurality of stacked cells described in Bosansky’s claim 1. Although not recited as a specific element, one practicing the combination of claim 2 would necessarily require spacers between the adjacent cells.
Plaintiff cannot proliferate its patent holdings merely by presenting claims which add to the basic envelope cathode arrangement of Oswin and Chodosh mechanical details such as spacers that, as broadly claimed, are obvious to those in the art. Cf. Pratt dc Whitney Co. v. United States, 170 Ct. Cl. 829, 345 F. 2d 838 (1965). In other words, two patents directed to the same combination cannot be sustained where patentability of the claims in both is predicated on the same feature. Since the ’270 patent covers the basic envelope cathode invention, and Bosansky’s work only purports to be an improvement thereof, it is claim 1 that must fall. In re Stanley, 214 F. 2d 151 (CCPA 1954); cf. In re Vogel, 422 F. 2d 438 (CCPA 1970).
Claim 3 merely adds a battery case having openings. Packaging of cells in a case is notoriously well known, as shown for example in the Hollman et al patent (finding 36) wherein *894the case holds the cells in an assembled relationship. Merely providing openings in the case for allowing air to reach an air-breathing electrode, which is all the claim requires, is an obvious concept.
Claims 8 and 9 add only details regarding the electrolyte and tilie Teflon backing of the electrode. These features were not the invention of Bosansky and were, at the time of his work, known in the art. They add nothing of patentable significance to the combination of claim 1.
Claims 1,3,8, and 9 are held to be invalid.

Moos Patent No. 3,531,387

This patent discloses a gas and liquid impermeable package containing a consumable metal anode, a separator material around the anode, and all of the electrolyte material needed to operate a metal/air cell over the life of the metal anode. This method of packaging the anode permits mechanical recharging of the metal/air cell of the ’270 patent without the need for bottles of corrosive electrolyte material.
Defendant does not seriously assert noninfringement but attacks validity, as well as contends for a license. Because of the conclusion that the license defense is a sound one, it is unnecessary to consider the issue of validity.14
Plaintiff developed the mechanical-recharging concept under its own in-house program and, by September 1965, had commenced packaging anode-electrolyte composites in polyethylene bags to test their shelf life. These shelf-life tests continued at a low level of activity until April 1966 when a comprehensive program to investigate the parameters affecting shelf life of packaged anodes was commenced. Up to that time, all of the packaging had been with polyethylene. Commencing in the early part of 1966, plaintiff entered into a series of contracts with defendant regarding the supply of mechanically rechargeable metal/air batteries. The packaging of anodes was part of the work under these contracts. Plaintiff continued its evaluation and work on packaging of anodes until October 1967, by which time it was determined that polyethylene was unsatisfactory due to its permeability. A composite of Mylar, polyethylene, and aluminum foil was then used to package the anodes.
*895The nature of tibe ’327 invention is such that its workability,, a prime requirement for a reduction to practice, Eastern Rotorcraft Corp. v. United States, supra, could not be ascertained until after the packaged anode-electrolyte composite had 'been subjected to suitable shelf-life tests. Those tests revealed that the polyethylene was unworkable because it did not provide a substantially liquid impermeable envelope. Since claim 1 expressly requires a liquid impermeable envelope, and since that limitation is of critical importance to achieving the objectives of the invention, it is apparent that there was no reduction to practice of the invention through use of the polyethylene. A workable material satisfactorily meeting the requirements of claim 1 was not found until 1967, at the time and during the course of work under contracts with defendant. (Findings 38,39.)
The standard patent rights provision contained in plaintiff’s contracts gives defendant a license under any invention “first actually reduced to practice” in the course of the contract. In view of the foregoing facts, it is clear that defendant has a license under the combination of claim 1, 'as Well as dependent claims 2,3,8, and 9.

Addendum

Because of the number of patents involved and the need to treat each patent individually, a few matters that either could not or should not be so compartmentalized remain to be mentioned.
While it is difficult to assess, on an individual basis, the relative contributions of the inventions of the ’900, ’909, and ’270 patents to the success of the BB-626( )/U, there is no doubt that they were of substantial importance. In head-on competition with the conventional silver/zinc battery, the BB-626 proved to be superior beyond any question. (Finding 40(c).) For example, the conventional battery required 10 hours to recharge while plaintiff’s battery requires only 10 minutes. It proved to be lighter, with 'greater capacity and higher power levels. This superiority was in large part due to the Teflon-bonded electrode (covered by the ’900 patent), the Teflon backing of the electrode (covered by the ’909 patent) , and the envelope configuration of the cathode and its *896mechanical rechargeability (covered by the ’270 patent). This is further evidence of the validity of these patents.
On the license issue, defendant has two arguments that have not been mentioned. The first is that the whole history of the dealings between the parties leads to the conclusion that it was the mutual effort of both plaintiff and defendant that led to the creation of the accused devices. A review of that history, however, rather readily reveals that this argument is not supported by the facts and must be rejected. Basically, the contracts between the parties fall into two categories, one for work on fuel cells 'and the second relating to metal/air batteries. The fuel-cell work was performed in the late 1950’s and early 1960’s and was related to Bacon-type cells with biporous nickel electrodes.15 The technology of biporous nickel electrodes is a separate subject and quite unrelated to the Teflon bonded-and-backed electrodes here in issue. The parties did not have any dealings on metal/air batteries until mid-1965, at the earliest. By then, plaintiff already had developed, tested, and demonstrated, with its own funds, the basic zinc/air battery that became the BB-626.
In sum, plaintiff’s work on Bacon cells did not generate, nor was it related in any way to, the inventions here in issue while the metal/air contracts were after the fact and dealt only with militarization and procurement of the batteries. To the extent patentable innovations were made under these latter contracts, defendant has already received express licenses from plaintiff (finding 42).
This leads to the second of defendant’s points which is that, because it is expressly licensed under certain patents covering improvements made by plaintiff during the course of militarizing the battery, it argues it should receive a license to practice the inventions in plaintiff’s basic patents. This contention has no substance, particularly in light of the express language in the contract documents which limits defendant’s rights to “subject inventions” made under the contract, and the language of the express license agreements *897which states that the Government shall not obtain a license “by implication or otherwise” to any inventions other than those expressly licensed. Eastern Rotorcraft Corp v. United States, supra; Erie Resistor Corp. v. United States, supra.
FINDINGS OF FACT
1. Plaintiff is a Massachusetts corporation having its principal place of 'business at Warwick, Rhode Island. Accused to infringe the seven patents in suit is a mechanically rechargeable metal/air battery (designated the BB-626 ( )/U), procured from the Eagle-Picher Company. Plaintiff has been record owner of the patents, identified below, since their respective dates of issuance:

Baehgrcnmd

2. The technology :is electrochemical devices for the generation of electrical energy by chemical processes, such devices being commonly referred to as batteries or cells. Historically, batteries have been classified as either primary (not rechargeable) or secondary (electrically rechargeable). Both classes employ a cathode, ian 'anode, and an electrolyte, and the basic chemical process is one of oxidation of a fuel at the anode, with the electrons from the oxidized material being transferred via an external circuit to an oxidizing agent at the cathode, which is reduced. The reactant 'at the cathode is often referred to as the “depolarizer.” A typical dry cell *898may use, for example, zinc as the anode, manganese dioxide as the cathode, and ammonium chloride as the electrolyte.
3. The term “fuel 'cell” also refers to a cell in which electrical energy is derived from the oxidation of a fuel. Classically, both electrodes in a fuel cell are invariant, gaseous reactants are continuously -fed to both electrodes, and ancillary equipment is utilized to control various operating conditions including the temperature and pressure of the cell, electrolyte circulation, and by-product removal. It is conventional practice to use catalysts in these devices. Fuel cells have always been understood by those in the art to be an electromechanical device for the generation of electrical energy by chemical processes and are considered to be a part of the battery field.
An example of a fuel cell is the Bacon cell (see, e.g., U.S. Patent No. 2,969,315) which utilizes hydrogen as the fuel, oxygen as the oxidant, and porous nickel electrodes. This cell will typically operate at over 200° C. and at elevated pressures with very high current densities.
4. Some batteries or cells possess characteristics of both a classical fuel cell and a conventional battery. An example is the metal/air battery in which a metal, for example, zinc, is used as the anode and provides the fuel to be oxidized while oxygen in the air is used as the oxidizing agent to be reduced at the cathode. The zinc anode is consumable and comprises a finite supply of fuel, while the cathode is invariant and air is supplied to it on a continuous basis. A catalytically active material is usually used at the cathode to accelerate the reaction process. The battery operates at ambient pressure and temperature. In Leesona Corp. v. Commissioner of Patents, Civil Action No. 1531-69, the Patent Office stipulated that a metal/air battery is a simple fuel cell, in that it is self-contained, requires no ancillary equipment, and is operable on air at ambient temperatures and atmospheric pressures. Those in the art consider a metal/air battery to be a hybrid type of fuel cell and a plurality of fuel cells are commonly referred to as a battery. Defendant’s employees sometimes refer to these as metal/air fuel cells.
5. One of the early metal/air batteries was an alkaline air-depolarized zinc system, exemplified by a railroad bat*899tery, employing a carbon cathode, a zinc anode, and a caustic electrolyte. Examples are found in United States Patents Nos. 2,044,923, 2,097,077, 2,275,281, and 2,863,769, and in PX-73 and 74. The capacity of this type of battery is limited by the quantity of electrolyte present. In general, no air-depolarized batteries or cells available prior to 1965 were capable of high current drains or of sustaining a high energy-density ratio. A major problem with the air-depolarizing battery was the need for a suitable porous carbon electrode that would contact the electrolyte, yet allow atmospheric oxygen access to the carbon surface. If the electrode was too porous, the electrolyte would flood the pores and prevent access of the gas to the electrode. This problem was partially solved by a wet-proofing treatment whereby the electrode surface was coated with a material to render it hydrophobic, i.e., water repellant to some degree. This treatment allowed the electrolyte to penetrate the electrode only to a limited extent, thereby allowing the air to pass through the unwetted portion of the electrode. The desired chemical reaction then took place along the line where the air and electrolyte met in the carbon electrode.
6. Various wet-proofing treatments of electrodes have been developed. By the early 1950’s, electrodes were being treated by impregnation with wax, grease, rubber, or other water-repellant substances to render the electrode substantially impervious to the electrolyte. U.S. 'Patents Nos. 1,544,030, 1,588,607, 2,017,280, and 2,938,064 are illustrative of these techniques. Powdered materials were also treated with a suitable substance, repellant to liquids, and then formed into electrodes, as disclosed, for example, in U.S. Patents Nos. 1,588,607 and 2,641,623. Typically, the substance was used in solution and was intended to coat the powder particles.
7. The problem of maintaining a porous, unflooded, carbon electrode also confronted those working on fuel cells. In a fuel cell, porous electrodes are necessary to permit the reacting gases to pass through the electrodes to the site of the electrochemical reactions at the solution-electrode interface. The wet-proofing treatment used in batteries was also used in fuel cells, particularly those using porous carbon electrodes, but other techniques were developed. Bacon’s *900H2-02 cell employed a biporous nickel electrode, consisting of a relatively coarse pore structure for most of the electrode thickness, and a thin, fine pore structure on the electrode side facing the electrolyte. This was found to provide a relatively stable liquid-gas interface in the region where the coarse and fine pore layers joined; however, it was necessary to maintain a controlled pressure in the gas-phase side of each electrode so that the gas would satisfactorily penetrate the electrode, but would not bubble through and form an explosive gaseous mixture.

Patent No. 3^19^900

8. (a) In 1958, as a part of a continuing interest in energy storage and conversion, the Kettering Foundation, Yellow Springs, Ohio, commenced an investigation into fuel cells. A principal objective of the investigation was the development of a fuel cell that could be operated at atmospheric pressure and at moderate temperatures, i.e., 100° C. to 200° C. This objective required the development of both a suitable electrolyte and a porous electrode of good electrical and electrochemical properties. Dr. Howard A. Tanner, Director of Research, and Glenn B. Elmore, a chemist, were involved in this program. The problem of waterlogged or flooded electrodes, particularly where hydrogen-containing materials were used, was known to Elmore and Tanner. They were also aware of prior waterproofing techniques using materials such as kerosene and wax.
(b) During the course of their work, Elmore and Tanner developed essentially three types of electrodes. The first (shown in Fig. 1 of the ’900 patent) had a catalyst mixed with a colloidal dispersion of a fluorocarbon, polytetra-fluoroethylene (du Pont’s Teflon), pasted on a screen. The second (shown in Fig. 2) used a porous carbon block treated with Teflon and then a catalyst-Teflon mixture was pasted on the block. The third consisted of a porous carbon block electroplated with the metal catalyst followed by a wet-proofing treatment with Teflon. Current densities obtained with the third electrode were only about half that achieved with the other two. By the fall of 1958, Elmore and Tanner had a working fuel cell having an electrode comprising an admixture of Teflon and electrocatalyst satisfactorily *901operating both at room temperature and at elevated temperatures.
(c) At the conclusion of their investigation, it was the opinion of Elmore and Tanner that they had developed 'a new type of porous electrode capable of achieving 'higher current densities over ia prolonged period than had theretofore been Obtained. They were well aware in 1958 that the improved porous electrode was usable in an electrochemical cell in which it was necessary to achieve 'a three-phase reaction of gas, liquid, and solid. Their interest being primarily in the H2 — 02 type of fuel cell, it was in that context that their application was presented to the Patent Office. It was also in that context that they first publicly disclosed their work, first in an oral presentation by Elmore to the Electrochemical Society in May 1960 and, later, in a paper published in July 1961 in the Joumal of the Electrochemical Society.
9. (a) The work performed by Tanner and Elmore in 1958 and thereafter was made the subject of patent application Serial No. 12, 758, filed March 4, I960. One object of the invention was the provision of an improved porous electrode which would not impede the diffusion of gas through the electrode. Various examples of electrolytes and electrodes were described in the application, including several electrodes in which a catalytic material, such as metallic silver powder, platinum black or palladium black, is mixed with a colloidal dispersion of a hydrophobic material, polytetrafluoroethyl-ene. As filed, the application contained claims directed to (1) a fuel combination, (2) an electrode for use in a fuel cell, and (3) a method of making the electrode.
(b) After 'an intensive examination in which none of the claims was found to be allowable, the application was abandoned in favor of a continuation application, Serial No. 332,812, filed December 23, 1963. Claims directed to a fuel cell using a particular electrolyte were ultimately found to be allowable but in conflict with similar claims contained in a Leib at al application, owned by Leesona 'Corporation. An interference was declared by the Patent Office but it was terminated when, on June 29,1966, Leesona acquired the Elmore and Tanner application from the Kettering Foundation. The application was then abandoned, this time in favor of a con*902tinuation-in-part application, Serial No. 009,985, filed December 22, 1966, by Leesona. This application, like the previous two 'applications, contained claims directed to a fuel cell combination, an electrode for use in a fuel cell, and a method of making the electrode.
(c) Throughout the prosecution of the three applications, the applicants presented claims directed to a porous electrode that included a colloidal suspension of a fluorocarbon mixed with a catalytic material to maintain porosity and to permit the diffusion of gases into the electrode. There is no basis in the file histories of the three applications on which to limit the electrodes described in claims 4 and 7 of the ’900 patent either to fuel cells, as distinguished from conventional batteries, or to electrochemical cells operating at temperatures of 100° C. or more. The concept of the electrode disclosed in the original application, its purposes, construction, and function, remained unchanged throughout the prosecution of the three applications. Those working in the art had long recognized the applicability of electrode technology both to fuel cells and other more conventional types of batteries, and those working with electrodes looked to developments in both areas of technology. The subject matter of claims 4 and 7 is fully supported by the original application Serial No. 12,758, and these claims are entitled to the benefit of the filing date of that application.
10. Although precise formulations are not specified, the disclosure of the ’900 patent is complete and will permit one skilled in the art to make the catalyst-Teflon electrode. Those skilled in the art, without the need for any experimentation, would recognize from the concept of the patent that the fluorocarbon should be limited in amount so that the electrode would be conductive. Otherwise, the proportions of the ingredients used in the electrode are not critical and may vary widely, dependent on the particular application contemplated by the user. A 50% Teflon, 50% catalyst mixture would be entirely satisfactory.
11. The use of an admixture of Teflon and catalyst in electrodes of the type developed by Elmore and Tanner has had a substantial impact on the industry. As stated by defendant’s expert, Dr. Gilman:
*903I can’t pinpoint tlie date, but I would say as soon as people found out that you could get good performance with Teflon-bonded catalysts, that they all got on the bandwagon.
Subsequent to the work of Elmore and Tanner, General Electric, Monsanto, American Cyanamid, Pratt & Whitney, and Leesona all began to work with Teflon-bonded electrodes. Today, that type of electrode is one of the most efficient electrodes available and Elmore and Tanner have received recognition as being the first to develop it.
12. Electrodes using a catalyst/Teflon admixture provide a cell which permits rapid current drain at high current levels and this, coupled with the advantage of light weight, results in a high power density. Those in the art, 'after the invention became known, were unable to explain why these electrodes were capable of such high current drains. In 1962 or 1963, Dr. Giner developed a theory that has received acceptance in the industry, 'as to the mechanism of operation of this electrode. That theory, based on the concept of “flooded agglomerates,” views the catalyst particles as forming porous agglomerates that are flooded with electrolyte and the Teflon particles as creating hydrophobic gas channels. The reactant gas diffuses through the Teflon channels to the flooded agglomerate sites throughout the volume of catalyst where it participates in the three-phase reaction.
Dr. Giner’s work in the development of this theory was, in part, funded by defendant through the research organization at Fort Belvoir, Virginia. As of now, his theory remains as the best explanation for the operation of these electrodes.
Plaintiff’s expert, Dr. Frysinger, was, for many years, employed first at Fort Belvoir and then at the Electronics Command at Fort Monmouth (ECOM), and has a long history of involvement with the development efforts of the battery and fuel cell industry. He testified in support of Dr. Giner’s theory and pointed out how, in light of that theory, the prior art electrodes differed from the Elmore and Tanner work. Defendant’s expert, Dr. Gilman, did not dispute the theory advanced by Dr. Giner, and recognized the uniqueness of the Teflon-bonded gas diffusion electrode but contended that *904these electrodes were first made by personnel at General Electric. This testimony was based on the work performed by Niedrach, as described in United States Patent No. 3,297,484.
13. (a) The most pertinent prior art is Berl Patent No. 2,275,281, a patent also considered by the Patent Office. The porous carbon of the electrode shown in Fig. 2 of the ’900 patent is used as a suport for the catalyst layer in the identical manner to the carbon block in Berl. The active layer in both Berl and the ’900 patent have the same electrochemical function, i.e., the reduction of oxygen from the air by an electrochemical process. The electrode of the ’900 patent differs from Berl in the choice and function of the polymer and catalyst mixture.
(b) In Berl, the wet-proofing polymer was intended to control penetration of the electrolyte into the porous carbon. This was achieved by dissolving the polymer, ethylcellulose, and mixing powdered carbon into the solution, thereby causing the particles of carbon to be coated, at least in substantial part, with the polymeric material. 'When dried, the polymer serves as a binder to hold the carbon particles together and, to the extent it is hydrophobic, the polymeric material will restrain penetration of the electrolyte into the electrode. The result is a line, defined by the limited penetration of electrolyte, where the electrolyte, gas, and catalyst come together 'and along which the necessary three-phase reaction occurs.
(c) Under Dr. Giner’s theory, the electrode of the ’900 patent has a wholly different structure from prior art such as that of Berl in that instead of the catalytic particles each being coated with the hydrophobic substance, in effect none of the particles has any coating at all. The particles are in intimate contact with each other in a substantial volume of the electrode, with the Teflon particles being dispersed throughout the electrode. When exposed to a gas and an electrolyte, the electrolyte will wet the catalyst particles throughout a substantial volume of the electrode and the chain of Teflon particles, which are hydrophobic but gas permeable, provides a path through which the gas may permeate the electrode to join with the electrolyte and the *905catalytic material for the three-phase reaction. Eather than occurring along a line, the reaction will occur throughout the volume of the electrode thereby providing an electrode of greatly increased capacity.
14. Polytetrafluoroethylene was available by at least 1951. By at least 1954, du Point had published a catalog detailing the properties and characteristics of its Teflon resin. By 1958, it had been suggested to use ethylcellulose, polyvinyl chloride, polyethylene, polystyrene, or rubber as binders in preparing porous electrodes. No one had suggested using a fluorocarbon such as Teflon, although its hydrophobic prop-ties were then known. The use of Teflon was confined to dipping an electrode in it in a conventional wet-proofing treatment, as disclosed in Keutschi Patent No. 2,951,106. Almost all of the work with plastic materials as binders used solutions of the material. Teflon is essentially insoluble. In 1954, Witherspoon et al investigated porous electrodes using plastic binders and concluded that the film coating achieved by materials such as rubber was superior to a particle mixture of polyethylene.
15. The BB-626 ( )/U battery is an electrochemical cell for the direct generation of electrical energy having an anode and a nonconsumable cathode with a catalytic layer (the black side) consisting of an admixture of materials including platinum black (an electrocatalyst) and a fluorocarbon (Teflon). The catalytic layer is exposed to the electrolyte of the cell and has a porosity sufficient to permit diffusion of gases (air) into the catalytic layer.

Patent No. 3,276,909

16. The electrode structure described in the ’909 patent comprises a porous polymeric matrix having a porous conductive, catalytically activating metal layer in intimate contact with one surface of ithe matrix. The function of the polymeric matrix is to support the catalytic material and control the electrolyte/reactant gas/electrode interface. The patent suggests that either a hydrophobic or hydrophilic polymer may be employed. If a hydrophobic polymer is used, it must be in contact with the reactant gas; if a hydrophilic polymer is used, it should be in contact with the electrolyte. *906Claim 9, the only claim in suit, 'specifies a hydrophobic polymer. Teflon, a fluorinated hydrocarbon, is a hydrophobic polymer.
17. (a) The Patent Office relied on Williams et al Patent No. 3,116,170 in rejecting claim 9 (claim 26 in the application). That patent discloses a fuel cell in which the electrode comprises a porous polymeric matrix having- a porous conductive catalytically activating metal layer in intimate contact with one surface of the matrix. Wiliams positioned the electrode with the polymeric material facing the electrolyte and, through careful selection of the pore size of the material, the electrolyte would penetrate through to the catalytically active layer. Williams’ preferred material is a hydrophilic polyvinyl chloride but a hydrophobic material such as polyethylene is also suggested.
(b) The only difference between claim 9 and the Williams et al patent is in the orientation of the polymeric matrix, the claim specifying that the catalytically activating metal layer faces the electrolyte instead of the gas. The Patent Office allowed claim 9 after plaintiff submitted the results of a comparative test that showed that a hydrophobic polymer-catalyst combination, oriented in the manner claimed, as compared to a hydrophilic polymer-catalyst combination, oriented in the manner disclosed in Williams, gave dramatically improved performance. For example, at a potential of 700 mV, the claimed arrangement obtained a current density-of over 75 ma/cm2 as compared to about 17 ma/cm2 with the-Williams orientation. These same tests showed that there was only a small difference in the performance of a hydrophilic polymer-catalyst electrode when its orientation was reversed.
(c) The results of the comparative tests were contained • in an affidavit submitted to the Patent Office and executed by Anthony Moos. The affidavit represented that the affiant held a degree of Doctor of Science in Physical Chemistry from the University of Paris. That representation was incorrect in that he does not hold a doctoral degree. The tests conducted and reported in the affidavit were of a factual nature and did not depend upon the technical qualifications of the affiant for their validity. The bases for the comparative tests conducted and reported to the Patent Office were *907Mly and accurately disclosed to the examiner and were appropriate for the limited purpose for which they were conducted, i.e., to show the effect of orientation of the polymer matrix.
(d) Both the test results submitted to the Patent Office by plaintiff, and other evidence in this case, demonstrate that the dramatic increase in current density obtained with a hydrophobic polymer matrix would not be obtained with a hydrophilic material, irrespective of its orientation. In experiments conducted at Pratt & Whitney, electrodes using Teflon as the polymer and platinum black as a catalytic material were investigated. These experiments confirmed the advantageous nature of those electrodes and suggested that the flooded-agglomerate theory of Giner as applied to the Teflon-bonded electrodes of Elmore and Tanner (finding 12) might also be applicable to a layered electrode of the Moos type.
18. There is no serious dispute that electrodes using a Teflon layer to support a catalytic layer represent a distinct advance in the electrode art. Dr. Giner considered it to be one of the two most efficient electrodes known, the other one being the Teflon-bonded electrode of the type disclosed in in the ’900 patent. Dr. Frysinger was of the same opinion. Defendant’s expert, Dr. Gilman, was of the view that a Teflon-backed electrode wherein the catalytic layer was Teflon-bonded is the best electrode at room temperatures known today.
19. In the Bacon-type cell, in which a biporous electrode is employed, the fine-pore structure where the desired reaction occurs faces the electrolyte and the coarse-pore structure faces the gas. To prevent penetration of the electrolyte into the coarse pores, it was necessary to establish a pressure differential which allowed the electrolyte to penetrate only the small pores. This was critical to the operation of the cell. When Williams proposed to use a layered electrode with a plastic matrix in lieu of the biporous structure, he reversed the orientation of the layers, placing the catalytic layer toward the gas and the plastic layer toward the electrolyte. In effect, the pore size of the plastic layer in Williams served as a gate that permitted only a controlled permeation *908of the electrolyte into the catalytic layer but provided unlimited access of the gas to that layer. In both Williams and Bacon, penetration of the electrolyte was the variable being controlled, in Bacon by the biporous structure and a pressure differential and in Williams by the pore size of the plastic film. Other prior art attempts at controlling the electrolyte include the use of paste electrolytes, electrolyte-impregnation techniques, and ion exchange membranes. The Moos electrode in which a hydrophobic layer is employed takes an approach opposite both to Bacon and Williams, and to the other prior art. He provides no control over the penetration of the electrolyte into the catalytic layer, allowing it to be entirely flooded by the electrolyte, and relies on the hydrophobic film or membrane 'as a gas-permeable barrier. Also contrary to Williams, Moos placed the polymer matrix on the gas side, an orientation that was inconsistent with the prior art concept of providing unrestrained access of the gas to the reactive layer.
20. General Electric was heavily involved in fuel cell research in the late 1950’s and early 1960’s. A substantial portion of their research effort was directed to the development of a cell that could operate satisfactorily 'at ambient temperatures and pressures. In 1959, the work at General Electric was, at least in part, devoted to work on the use of ion exchange membranes. In 1961, almost 3 years after Elmore and Tanner conducted their experiments, and over 1 year after their application had been filed, General Electric filed an application, disclosing the use of a Teflon-bonded electrode, asserting the improved performance of these electrodes over prior art electrodes. As of the filing of that application, General Electric was using an electrolyte-impregnated solid matrix as a technique for restraining the electrolyte. In October 1962, a year and a half after the Moos application was filed, General Electric filed another patent application, disclosing a layered electrode made up of a hydrophobic polymeric matrix (Teflon) with a Teflon-bonded catalytic layer supported thereon. The application disclosed that the Teflon matrix was oriented toward the gas and stated that the “surprising” result was the good performance of the electrode.
*90921. On March. 11,1966, plaintiff filed a patent application in the name of Harry G. Oswin in which plaintiff sought to obtain claims directed to the Moos electrode disclosed in the ’909 patent, but in the context of a metal/air battery. During prosecution of that application, plaintiff took the position before the Patent Office that the ’909 patent did not disclose the use of the Moos electrode in a metal/air battery and that there was no teaching in the ’909 patent that the Moos electrode could be used advantageously as the air-depolarized cathode in lan air battery. Failing to persuade the Patent Office of its position, plaintiff appealed to the United States District Court for the District of Columbia. In connection with that proceeding, Civil Action No. 1537-69, plaintiff and the Patent Office entered into a stipulation that the electrodes of the ’909 patent are generic to all fuel cells, including simple fuel cells such as metal/air batteries. Although Moos testified in the District Court that he had contemplated that his electrode would, at all times, be operated under a positive gas pressure and it was his belief at the time that it would not be operable under atmospheric conditions, the District Court concluded that one of ordinary skill in the art would readily recognize that the Moos electrode could be used 'as an air cathode in a metal/air battery.
22. The BB-626 ( )/U battery utilizes an electrode comprising a porous hydrophobic polymer matrix (the white side consisting of FTFE) and a porous conductive catalyt-ically activating metal layer (platinum black) on one side of the PTFE. The battery is a fuel cell for the generation of electrical energy from a fuel and 'an oxidant. The means for supplying the reactants to the electrodes include openings in the housing through which air is supplied to the cathode. The fuel cell reactant at the anode is the zinc which is a part of the anode construction and is supplied on a batch 'basis each time a spent anode is replaced with a fresh one.
23. (a) On February 21, 1958, plaintiff and defendant, through its Department of the Navy, entered into contract NOas 58-A14-C, the purpose of which was to fabricate, test, and 'furnish to the Navy, on a cost-plus-fixed-fee basis, a fuel cell capable of producing certain levels of power, the total contract price being $128,779.50, of which $7,290 was the fee. *910Work under this contract commenced on May 1, 1958; tbo actual experimental work terminated as of about January 1960; the 'available funds were exhausted by September 28, 1960; and a cell was delivered to defendant in October 1961. The contract contained the standard patent rights clauses, which state:
(a) * * *
(1) The term “Subject Invention” means any invention, improvement or discovery (whether or not patentable) conceived or first actually reduced to practice * * *
* * * in the performance of * * * work called for or required under this contract ■* * *
*****
(b) (1) The Contractor agrees to 'and does hereby grant to the 'Government an irrevocable, nonexclusive, nontransferable, and royalty-free license to practice * * * each Subject Invention * * *
* $ * * *
(2)
‡ ‡ ‡
(iii) * * * Nothing contained in this Patent Nights clause shall be deemed to grant any license under any invention other than a Subject Invention.
¡H # *
(b) The contract did not require a Bacon-type fuel cell; however, plaintiff’s work under this contract, as well as under a contemporaneous Air 'Force contract, was devoted to that type of cell. Both the Navy 'and the Air Force were aware of the nature of the work being performed and neither raised any objection. In attempting to improve the biporous nickel electrodes theretofore used in Bacon cells, plaintiff experimented with a Teflon-coated coarse-pore metal plate and evaluated its bubble pressure characteristics. Experimental work with Teflon-coated plates extended through June, July, and August 1958, in an attempt to come up with an electrode having an acceptable bubble pressure. Finding no improvement in bubble pressure, plaintiff never tested the electrodes or used them in a cell and that phase of the work was abandoned. However, the substance of the work was duly reported to the Navy in three monthly progress reports.
*911Similar work bad been performed by plaintiff in January 1958, prior to this contract, when a hydrophobic silicone material had been coated on a coarse-pore metal plate and evaluated for bubble pressure.
(c) The fuel cell ultimately supplied to the Navy was a Bacon-type cell constructed in England, together with certain subsystems developed by plaintiff. These subsystems included a gas control system, a hydrogen circulation-water vapor removal system, and a cryogenic fuel storage system. By January 1960, the Bacon cell had been ordered from England and no further work on electrode development was being performed, it 'having been determined to use porous sintered nickel electrodes in a circular configuration.
(d) The Navy was of the view that plaintiff made no contribution or invention in the field of fuel cells and electrodes during the course of this contract. Although the fuel cell delivered to the Navy did not fulfill the terms of the contract, none of the fuel cell contracts then being performed were successfully completed. Plaintiff and the Navy entered into a supplemental agreement reducing the fixed fee by some $2,000, which represented an adjustment related to the percentage of completion of the contract, and the Navy considered the contract closed after the hardware had been delivered.
(e) Moos’ work on which the ’909 patent is based was performed in late summer or early fall of 1960, during the course of experimental work funded by plaintiff on various hydrophobic and hydrophilic sheets and their orientation with respect to the gas and the electrolyte. None of this work was related to the sintered nickel electrodes plaintiff was supplying to the Navy, those electrodes having been procured from England. At the time plaintiff made the decision to supply the Navy with electrodes and a Bacon cell from England, that type of cell had the highest theoretical current density of electrode area of any known fuel cell.

Patent No. 3,438,815

24. This patent discloses a layered electrode construction in which a Teflon-bonded catalytic layer is combined with a mioroporous layer serving as the support for the catalytic layer. The specification states that the metal layer should *912have a pore size in the range of 1 to 50 microns in diameter in order bo establish the desired bubble pressure. In one embodiment, the patent discloses a<n electrode consisting of a Teflon layer, a Teflon-bonded Catalytic layer, land a micro-porous metal layer. Claim 12, on which claims 15 and 16 are dependent, is as follows:
An electrochemical cell for the generation of electrical energy comprising an electrolyte chamber containing lan electrolyte, at least one oxidant electrode, at least one fuel electrode, said electrodes partially defining said electrolyte chamber and being in contact with said electrolyte, at least one of said electrodes 'being a sandwich-type structure Wherein a porous conductive eatalytically activating layer consisting essentially of a hydrophobic polymer and catalytic metal particles is in intimate contact at one surface with a porous hydrophobic polymer matrix and the second surface is in contact with a porous self-sustaining metal layer of uniform and controlled porosity, said porous self-sustaining metal layer facing the electrolyte chamber and said porous self-sustaining metal layer being in contact with the electrolyte of the cell.
25. In light of the patent specification and the arguments advanced to the Patent Office, the limitation in claim 12 of a “porous self-sustaining metal layer of uniform and controlled porosity” must be restricted to porosities in the micro-porous range.
26. The expanded metal grid in the accused battery is not a micro-porous structure; it is not used as a device to control bubble pressure, nor does it do so. Its only function is that of a current collector. The use of screens as current collectors was known in the art long prior to the filing date of this patent, as shown, for example, in the ’900 patent in suit, and in Niedrach eta! Patent No. 3,432,355.

Patent No.

27. This patent discloses an electrode comprised of an unsintered Teflon layer and a catalytic layer. This sintering temperature of Teflon is 327° C. The patentee points out that, when Teflon is heated above 327° C., the porosity of the Teflon structure is decreased and small cracks or breaks occur in the Teflon sheet. Although these cracks or breaks *913do permit the diffusion of gas through the sintered Teflon, they may also permit electrolyte to leak through, resulting in a condition known as weepage. Claim 1, the only independent claim, is as follows:
An electrochemical device comprising a fuel electrode, an oxidant electrode, and an electrolyte in contact with each of said electrodes, at least one of said electrodes being non-consumable and electrochemically active with a reactant material and comprising a continuous polytetrafiuoroethylene film fabricated below the transition temperature of polytetrafiuoroethylene which is 327° C., said film being gas permeable and free from liquid aqueous electrolyte seepage and a catalytic material comprising an electrocatalyst in intimate contact with one surface of said film, said catalytic material being in contact with the electrolyte of the device and said polytetrafiuoroethylene film being exposed to said reactant material, said electrode being fabricated at a temperature below the transition temperature of poly-tetrafluoroethylene, which is 327° C.
Dependent claims 3, 4, and -6 add details regarding the Teflon-bonded electrode while dependent claim 11 is directed to a consumable zinc amode. None of the features described in these claims was developed by the patentee Fishman.
28. (a) In the ’900 patent of Elmore and Tanner, it is stated that the mixture of silver powder 'and Teflon should be heated only to about 300° C., at which temperature “the Teflon is not heated to the point where the open porous structure of the Teflon-silver mixture might be destroyed. ”
(b) In the Moos ’909 patent, specific examples for producing electrodes are given. Examples 1 and 2 disclose a silver-ized polyethylene sheet. The temperatures employed in the processing of the polyethylene do not exceed 150° C. The patent states that polytetrafiuoroethylene could be substituted for the polyethylene in both of the examples. If such a substitution were made, the fabrication process described in those examples would not sinter the Teflon.
(c) Croze et al Patent No. 2,689,805, issued in 1954, describes a Teflon film coated with thin metallic layers. This patent discloses that unsintered Teflon is porous to air while sintering of Teflon renders it nonporous.
*914(d) Advertising literature, circulated by du Pont in 1957, described Teflon as having very low permeability after it lias been sintered.
(e) Unsintered Teflon film was commercially available in April 1961, the filing date of the Moos ’909 patent. In his experiments in 1964, the patentee Fishman used a commercially 'available unsintered Teflon film.

Patmt No. 3,1)36$70

29. (a) This patent discloses a mechanically rechargeable metal/air cell having a gas permeable envelope cathode, i.e., a cathode in an envelope configuration which forms 'a complete enclosure closely surrounding the anode. A metal anode and electrolyte are contained within the space defined by the envelope cathode. The cell is recharged merely by removing an expended anode and replacing it with a fresh anode. The anode is a metallic material and the electrolyte is preferably trapped in a suitable matrix or wrapper surrounding the anode. The wrapper serves as an insulator between the anode and the close-fitting cathode.
(b) The anode-cathode structure of the ’270 patent lends itself to a compact design requiring only a low volume of electrolyte. A high energy-to-density and high energy-to-volume cell capable of high current drains can be achieved. This is in large part due to the Teflon-layered electrode structure but also in part due to the envelope configuration and the close-fitting relationship between the anode and cathode. In effect, this relationship is analogous to a letter and its envelope, the anode being the letter and the cathode the envelope, thus providing a minimum, electrode spacing, a minimum quantity of electrolyte, and intimate contact among the cathodic surfaces, the separator, electrolyte, and the anodic surfaces. It further contributes to high-anode utilization with minimum electrolyte requirements. No prior art system was capable of using two porous electrodes with low-electrolyte requirements.
(c) The term “bi-oathode” was used in the specification and claims as originally filed. After interviews with the examiner, and in an amendment filed February 23, 1968, applicants’ attorney amended the claims to call for an “envelope” cathode. In making this amendment, it was stated:
*915In order to more accurately define tibe present invention, tbe claims bave been amended to read “envelope cathode” in place of “bi-cathode.” In view of tbe modifications to tbe claims, to bave conformity, the specification has been amended 'at page 4, line 19, to indicate that tbe term “bi-catbode” and “envelope cathode” are synonymous.
As defined in tbe RANDOM HOUSE DICTIONARY OF THE ENGLISH LANGUAGE 477 (1967), “envelope” means to enclose or surround.
30. (a) Defendant does not seriously contest infringement of tbe claims of tbe ’270 patent here in issue. In support of its defense of obviousness, defendant relies on tbe following prior art patents:

(b) These patents, with the exception of Heise and Thompson, are pertinent only to show that certain features such as zinc anodes, separators wrapped around anodes, and entrapped electrolytes were known prior to tbe filing date of tbe ’270 patent. As is apparent from tbe prior art, tbe conventional metal/air or railroad battery bad no provision for recharging. When tbe anodes were consumed, tbe battery was either discarded or, with some, a new cathode-anode assembly was used to rebuild tbe battery. Tbe electrolyte was almost always shipped separately and was added to the battery when it was ready to be activated. Tbe volume of electrolyte was made as large as possible. The conventional secondary battery, such as tbe silver-zinc BB-451/U battery of tbe Marine Corps, required battery-charging equipment and a considerable period to effect tbe recharge.
(c) Heise discloses a metal/air battery consisting of an anode, cathode, electrolyte, and current collector mounted in a 'hinged, rigid, boxlike frame to allow tbe ready removal of *916the 'anode 'and cathode. A substantial space is provided between the 'anode and cathode surfaces. This battery is a so-called “reserve” type in that some part of the battery ¡is left unassembled to prevent its discharge until the battery is ready to be used. Heise suggests that the anode may be kept separate. Alternatively, the paste electrolyte may be held in -reserve or -an anhydrous assembly requiring the addition of water may be employed. There is an express disclosure in the patent of “replacement” of the anode (p. 1, col. 2, line 69). This replacement process would involve the steps of removal of the spent anode from between the two cathodes and replacement of that 'anode with a fresh anode.
(d) Thompson et al discloses an air-depolarized 'battery utilizing a carbon cathode and a zinc anode, designed so that the zinc anode may be replaced after it is exhausted. Thompson contemplated that the life of the anode would be approximately the same as the active chemical part of the electrolyte so that both the anode and the electrolyte would be changed at the same time.
31. (a) Defendant also relies on work by General Electric in developing a magnesium-air battery under Task 89, a Government-financed project for an undisclosed 'agency, as an anticipation of the ’270 claims. That battery has a mechanical recharging capability, using replaceable magnesium 'anodes with' salt water as the electrolyte. The anode-cathode structure is shown in Kent Patent No. 3,457,115, filed December 3,1965, and issued July 22,1969.
(b) Plaintiff’s contention that the Oswin-Chodosh invention was conceived in October 1964, and reduced to practice by December 1964, has not been satisfactorily proven. The invention disclosure form executed by the inventors is dated May 3,1965; it contains only a broad description of the idea of replacing ¡anodes. There is no mention of any specific embodiment and no description of an envelope cathode. The indication in earlier reports that cathodes had been tested repeatedly against 'anodes is ambiguous at best and does not corroborate the oral testimony of plaintiff’s witnesses. There is no persuasive evidence that an envelope cathode was conceived by plaintiff prior to G.E.’s work.
*917(c) In June 1964, G.E.’s work on a magnesium-!air battery included consideration of a configuration in which, a single anode was positioned between two cathodes. By October 1964, G.E. had devised the basic anode-cathode structure shown in the Kent patent and had operated cells using that configuration. This basic structure included a pair of cathodes with an anode removably positioned therebetween for mechanical rechargeability. Although some leakage problems were encountered with this battery throughout the Task 89 program, the workability of the basic configuration and the mechanical rechargeability of the battery had been demonstrated before the end of 1964.
(d) In October 1964, Leesona began formal consideration of a program for the development of an air-depolarized battery. Up to that time, its major efforts had been in fuel cells and batteries other than metal/air batteries. As of that time, Leesona had completed some experimental work on metal/air cells and had demonstrated the superiority of the Teflon electrode to the prior art electrodes; however, the envelope cathode and the rechargeable concept had not yet been developed. By December 1964, an evaluation of a bi-cell, consisting of two cathodes supported on a frame with an 'anode in between, had been completed. Documents dated in April and May 1965 are the first clear disclosures of an envelope cathode and the mechanical-recharging concept.
(e) On November 20,1964, the United States Army Electronics Laboratories issued technical guidelines for research and development work in the field of metal/air batteries. These guidelines were republished on March 5,1965, but with the additional provision:
6. A study of cell rechargeability (i.e. replacement of spent anodes and electrolytes with fresh materials) shall be made. Cell design should be such that this recharging can quickly, easily, 'and safely be accomplished. * * *
(f) General Electric’s work under Task 89 extended from June 1964 to August 1965. The substance of the work performed was periodically reported to the secret customer but was otherwise maintained secret and confidential within G.E. The filing of the Kent application on December 8,1965, *918was the first step taken by G.E. toward a public disclosure of this work.
32. (a) The combination of an envelope cathode and removable anode was new to the field of metal/air batteries. None of the prior art had used a cathode both in a close-fitting relationship to a removable anode and to serve as a receptacle for the electrolyte. The essentially contemporaneous work of G.E. 'in developing the magnesium/air battery evolved a removable anode but the cathodes on the opposed sidefaces of the boxlike frame are spaced apart a substantial distance, much like the Heise arrangement, and this spacing, together with the rigidity of the box structure, precludes a close-fitting, intimate engagement of the cathodes and anode. Like conventional railroad batteries, a substantial volume of electrolyte, 9 grams/ampere hour, is required for the G.E. structure. Dr. Frysinger testified that tests he conducted revealed that the G.E. battery produced 28.8 watt hr./lb. while plaintiff’s battery with the close-fitting envelope cathode produced over 100 watt hr./lb. and that the difference in performance was due to the envelope cathode structure.
(b) In the period 1966-68, the Marine Corps instituted a program to determine whether metal/air batteries could be used to power its radio sets in lieu of the silver/zinc batteries, the BB-151/1J, then being used. Three metal/air batteries were tested, the G.E. magnesium/air battery developed under Task 89, a zinc/air battery of Yardney Electric and plaintiff’s zinc/air battery. Each of these used a replaceable anode. The G.E. and Yardney cells were of substantially the same construction, employing the boxlike cathode structure. Plaintiff’s cells used the envelope cathode. The G.E. cells were rejected at an early stage of testing due to an inability to produce sufficient electrical energy. The Yardney battery was also rejected. After complete testing of plaintiff’s battery, including field tests in Vietnam, the Marine Corps reached the conclusion that plaintiff’s battery should replace the BB-451/U. The tests revealed that, in addition to superior capacity and cycle life, plaintiff’s battery with the envelope cathodes and removable anodes could be recharged in 10 minutes as compared to the 10 hours required for the BB-451/U.
*91933. The method steps Recited in claim 19, i.e., (1) discharging the metal anode, (2) removing the discharged anode, and (3) inserting a fresh anode, are 'all disclosed or inherent in Heise. Claim 19 differs from Heise only in the specific structure of the envelope cathode recited in the claim. G.E.’s work under Task 89 also used the same method steps for replacement of the anode.
34. (a) On June 15,1965, plaintiff entered into a cost-plus-fixed-fee research and development contract, AF 33(615)-2680, with defendant’s Wright-Patterson Air Force Base, to provide a high discharge rate, high specific energy electrochemical power source for aerospace applications. Under this contract, plaintiff was to select a couple, conduct experimental work on the couple, and build and test cells and batteries using the selected couple. Specific performance requirements were listed in the contract. The standard patent rights clauses were included in the contract.
(b) Plaintiff selected an aluminum/oxygen couple as its first choice to investigate, with zinc/oxygen as a second choice. Defendant was advised by plaintiff that Leesona had its own inhouse program on zinc/air batteries.
(c) Plaintiff’s detailed studies of the aluminum anodes indicated that greater research effort than allowed under the contract would be required. The Air Force decided that the effort should be redirected to defining the limitations of the aluminum/oxygen system and to providing a zinc/air battery for evaluation. This redirection of effort was formalized in a supplemental agreement dated March 4, 1966, under the terms of which plaintiff’s fixed fee and the estimated cost were reduced by about two-thirds.
(d) Prior to any work under this contract, plaintiff had the concepts of a mechanically rechargeable zinc/air battery, had built batteries using those concepts, had tested the batteries, and had prepared data in a brochure describing the battery. Plaintiff’s mechanically rechargeable zinc/air battery was demonstrated by plaintiff to military personnel on or about September 9, 1965, and one was delivered to the Engineer Research and Development Laboratories at Fort Belvoir, Virginia, on or about December 30,1965.
*920(e)' Although certain aspects of the technology developed by Leesona were employed in the work performed under this contract, none of that technology was either first conceived or first reduced to practice thereunder; rather, it was previously developed under internal programs of Leesona and funded by Leesona.

Patent No. 3,378,406

35. (a) This patent discloses a battery of cells employing the envelope cathode and replaceable-anode concept of the ’270 patent and adds the feature of intercell spacers between the cathodes to allow free and direct access of air over the entire surface of the cathode. With the particular spacers disclosed, a plurality of cells may be stacked in a compact configuration while yet providing the requisite air flow to the cathode to obtain a high-energy output. The spacers exert pressure against the faces of the cathodes so that the desired intimate Contact of the electrodes is maintained. The spacers also tend to prevent cell “growth” by exerting pressure against the cathode face.
(b) The claims of the ’406 patent were allowed after two interviews with the examiner. There were no formal office actions by the Patent Office on the merits of the application. The only advantage of the claimed combination stated by the applicant to the Patent Office is summed up in the following statement from one of the two amendments submitted by plaintiff:
* * * the inventive feature of the present disclosure is the provision of a metal/air or metal/oxygen battery comprising a plurality of cells, each of which has a cathode surface which needs to be in contact with air or oxygen for operation. The objective is accomplished by having a spacer element having openings for the passage of air or oxygen positioned between adjacent cells of a stack. These spacer elements can be integral with, or separate from the cathode.
(o) Rosansky’s contribution to the combination set forth in claims 1, 3, 8, and 9 rests solely on the spacer elements recited. At trial, Dr. 'Chodosh testified that the intercell spacers perform several important functions in that they allow “specific quantities” of air to the cathodes, not enough *921to create a dry-out problem but enough to avoid polarization and overheating. The patent specification states that the “essential feature” (col. 3, lines 31-33) of the spacers is to permit access of air to the cathodes. There is nothing in the specification about limiting the air to a specific quantity; nor is there any structure recited in the claim that would inherently perform such a function.
(d) Claims 1 and 3 are directed to the same basic combination 'as claim 2 of the ’270 patent. Each of these claims calls for a plurality of cells, with each cell comprising:
1. An envelope cathode comprising a hydrophobic polymer membrane and a conductive catalytic coating on the inner surface.
2. A metal anode positioned within each envelope cathode.
3. An electrolyte in the space separating the anode and cathode.
4. Means for retaining the elements of the cells in operable association.
■Claim 1 of the ’406 patent adds to the combination the provision of intercell spacers.
36. The use of spacers between electrode surfaces was well known long prior to 1965 to those in the battery and/or fuel cell field. Jaffe Patent No. 3,005,943, for example, teaches an oxygen electrode made up of a plurality of thin sheets arranged in a stack with spacers between each sheet, the spacers being a woven mesh screen that allows the oxygen to contact the faces of the sheets. Mond et al Patent No. 409,365 and Vahldieck Patent No. 3,012,086 likewise teach that spacers may be positioned between a stack of cells to provide access for the flow of gas over the electrode surfaces. Porous separators between adjacent electrodes have also been used, as shown in Hollman et al Patent No. 2,727,083; 'and other types of spacers are shown in Ruetschi Patent No. 2,951,106, Bacon Patent No. 2,969,315, Banger et al Patent No. 3,252,839, and Harris Patent No. 1,297,157. The G.E. work on a magnesium/ air battery (finding 31) included the use of spacers that defined openings between the stacked cells to provide access of air to the cathode surfaces. At about this same period of 1964-65, Eagle-Picher designed a zinc-oxygen system (ZOX) in which spacers were used between stacked cells. Those with *922ordinary skill in the art would have readily recognized that the flat cells of Heise Patent No. 1,899,615 also could be stacked together and that spacers would have to be provided between adjacent cells to permit air access to the cathode surfaces.

Patent No. 3,531,3?J7

37. This patent discloses a substantially liquid and substantially gas impermeable package containing all of the anolyte elements, i.e., metal anode, separator material, and electrolyte, necessary for the complete recharge of a mechanically rechargeable cell of the type disclosed in the ’270 patent.
Claims 1, 2, 3, 8, and 9 are accused to be infringed and are as follows:
1. As a new article, an assembly including select elements for use with metal/air depolarized cells, said cells comprising as essential elements an air depolarized cathode, a consumable metal anode, a hydrophilic separator, and a material capable of functioning 'as an electrolyte in aqueous solution, said assembly including from said essential elements only said anode, said hydro-philic separator, and said material, said hydrophilic separator disposed around and in contact with said anode, at least one of said separator and anode including a quantity of said material capable of functioning as an electrolyte in aqueous solution, said quantity of said material in said separator and anode constituting the sole source of electrolyte material and being sufficient to operate the metal/air depolarized cell substantially over the life of said anode when disposed in said cell without requiring additional electrolyte material or any other material with the exception of water, and a substantially liquid and substantially gas impermeable envelope enclosing said assembly.
2.. The article of claim 1 wherein the electrolyte material is an alkaline material.
3. The article of claim ti wherein the alkaline material is potassium hydroxide.
’ if! % %
8. The article of claim 1 wherein said anode comprises a porous metal body.
9. The article of claim 8 wherein the metal is zinc.
*92338. (a) Work on storing anodes in-bags commenced at Leesona in the summer of 1965, when a few anodes, activated by immersion in electrolyte, were placed in polyethylene bags. The anodes were left in storage for varying periods and then tested to determine the effect of storage on their capacity. This program continued on a limited scale through 1965 and into 1966. In April 1966, a comprehensive storage analysis program was instituted to ascertain wet storage life of a zinc anode and separator impregnated with electrolyte, and to determine the importance of certain variables in that storage life. Evaluation of suitable packaging for the anode continued to July 1967, by which time it was decided that polyethylene was inadequate in preventing moisture penetration and consequent loss of capacity and dimensional changes in the stored anodes. As a temporary measure, a composite wrapper of Aclar, Mylar, and polyethylene was adopted. Ultimately, satisfactory wrappers were found to be made up of layers of polyethylene, Mylar, aluminum foil, and Kraft paper.
(b) The polyethylene bag employed by Leesona in its early work was not a substantially liquid impermeable envelope, when considered in the context of the objectives sought to be achieved. Because of the moisture permeability of that material, the packaged anodes had diminished capacity and were not suitable for use after extended storage. The first assembly of a metal anode, separator, and electrolyte in a substantially liquid and gas impermeable package susceptible of extended storage without undue loss of capacity was made in 1967.
39. On March 21, 1966, plaintiff entered into .contract DA 28-043 AMC-02082 (E) with the procurement division of the United States Army. Electronics ' Command (ECOM) at Fort Monmouth, New Jersey. That contract covered 12 items of work, including the supply of 10 24-volt metal/air battery systems with 300 anode electrolyte recharge kits, and 12 60-watt metal/air battery systems with 672 anode electrolyte recharge kits. The contract price was $300,000, with plaintiff obligated to expend up to an additional-$100,000 of its own funds without reimbursement should the cost ex-' ceed the contract price. The contract included the standard *924patent rights provision; however, it was agreed that the contracting officer would attempt to obtain a deviation to that provision which would exclude any preexisting invention that might be first actually reduced to practice in the performance of the contract. No deviation was obtained. Work under this contract extended through 1967, and beyond. Plaintiff’s storage tests on packaged anodes were directly related to its performance under this contract.

Additional Findings

40. (a) A number of contracts were awarded to plaintiff by ECOM in the period 1966-68, the purpose of all of which was to militarize ¡Leesona’s mechanically rechargeable zinc/ air battery. Each of the contracts contained a patent rights clause.
(b) Contracts were also let in 1967 to General Electric and Yardney for the development of a mechanically rechargeable metal/air battery. The batteries they produced were unsatisfactory and their contracts were terminated in late 1967. The effort then continued with Leesona. By September 1968, defendant had tested plaintiff’s battery, found it performed exceptionally well, and determined it to be the only one that met the military power requirements and also the environmental and ruggedness requirements for military field operation.
(c) Various comparative tests conducted by defendant have demonstrated the superiority of plaintiff’s battery, to the conventional silver-zinc battery. For example:

Leesona Siloer/zlnc

Capacity---25(+) amp hrs-9.5 amp hrs.
Cycle time-21 hrs. 7 min_11 his. 16 min.
Recharge time-10 min_10 hrs.
Weight..12.51b_ 16.51b.
In terms of energy density, defendant evaluated plaintiff’s battery at around 100 watt hours per pound, twice that of the closest competing battery system. Plaintiff’s battery was voted one of the outstanding inventions in the 1966 industrial research competition, and has been enthusiastically received by the military, which has viewed it as a “significant improvement” over prior art systems and a “new important power source.”
*92541. After successful testing of the Leesona battery in 1968, immediate adoption and procurement was recommended by the Marine Corps. Initially, defendant intended to procure the batteries from plaintiff as the sole source; however, it was later decided the procurement would be on a 'limited competitive basis. Plaintiff then offered to, and did, assist in preparing the technical portion of the request for proposal issued to prospective bidders.
Plaintiff was runner-up in the subsequent bidding, Eagle-Picher submitting the low bid. After the contract was awarded to Eagle-Picher, plaintiff filed a protest of the award, but it was rejected. The BB-626( )/U battery procured by defendant from Eagle-Picher is a substantial copy of plaintiff’s metal/air battery.
42. During the course of its work in militarizing its battery, plaintiff made certain modifications and improvements. Some of these are the subject of issued patents or pending applications. The parties have entered into express royalty-free licenses for the inventions disclosed and claimed in the following patents or applications:
Patent No. 8,513,030 (anode terminal jack construction)
Application S.N. 627,196 (voltage regulator and blower arrangement)
Application S.N. 627,194 (metal anode, and wrapper)
Patent No. 3,595,700 (method of making electrodes)
Patent No. 3,474,324 (voltage regulator)
Patent No. 3,592,693 (electrolyte impregnated anode)
Patent No. 3,630,785 (separator construction)
Each of the license agreements includes the following provision : “Nothing contained herein shall be deemed to grant, by implication or otherwise, any license to the Government under any invention other than those covered by the aforesaid application for patent.”
CONCLUSION OF LAW
Upon the foregoing findings of fact and opinion which are made a part of the judgment herein, the court concludes as a matter of law that
a. The following claims are valid and infringed and that defendant has no license thereunder:
*926Patent No. 3,419,900, claims 4 and 7;
Patent No. 3,276,909, claim 9;
Patent No. 3,436,270, claims 1, 2, 3, 5-8, 10, 16, and 17.
b. The following claims are invalid:
Patent No. 3,436,270, claim 19;
Patent No. 3,553,024, claims 1,3,4,6, and 11;
Patent No. 3,378,406, claims 1,3,8, and 9.
c. Claims 12, 15, and 16 of Patent No. 3,438,815 are not infringed by defendant.
d. Defendant is licensed under claims 1, 2, 3, 8, and 9 of Patent No. 3,531,327.
Accordingly, plaintiff is entitled to recover reasonable and entire compensation, the extent of which will be determined in further proceedings pursuant, to Rule 131.

 There is much confusion in the use of the terms “fuel cells” and “batteries.” Battery is used, in a loose sense, as a name for a -wide variety of different types of electrochemical devices. It is used to denote a plurality of cells, yet it is also used when referring to a single cell, e.g., a flashlight “battery.” Fuel cells are a part of the general “battery” field and a plurality of fuel cells are commonly referred to as a battery; however, the term “fuel cell” normally refers to a particular type of electrochemical device. (Findings S, 4.)

 Claim 7, also asserted to be Infringed, provides :
“The electrochemical cell of claim 4 wherein the fluorocarbon polymer Is polytetrafluoroethylene."

 Nor are any of the other patents that have filing dates subseguent to March 4, 1960.

 The parties are In disagreement whether the Witherspoon et al publication Is properly a reference. Since the claims are considered to be valid even If Witherspoon is a reference, It has been unnecessary to resolve that Issue.

 Defendant’s contention that the chemical reaction Is the same Irrespective of where It occurs Is, of course, correct but entirely beside the point.

 Since, under defendant's contracts with plaintiff, Teflon-bonded electrodes were not a “subject invention,” expressly licensed to the Government, this is not a situation where, by a subsequently acquired patent, the contractor attempts to dominate rights previously granted to the Government. Compare, AMP, Inc. v. United States, 182 Ct. Cl. 86, 389 F. 2d 448 (1968), cert. denied, 391 U.S. 964.

 The suggestion that plaintiff reshaped the Elmore and Tanner application based on Inputs from Government contract work Is without any evidentiary support.

 Although defendant also asserts a license under an Air Force contract, It has not identified any specific work performed by plaintiff that would give rise to a license as a result of that contract.

 While the better practice Is to treat both the validity and Infringement issues, Sinclair Co. v. Interchemical Corp., 325 U.S. 327 (1945), particularly in view of the public interest in the validity issue, Ditto, Inc. v. Minnesota Mining & Manufacturing Co., 336 F. 2d 67 (8th Cir. 1964), it is not always necessary to do so. Dresser Industries, Inc. v. United States. 193 Ct. Cl. 140, 432 F. 2d 787 (1970). Where, as here, noninfringement is clear and invalidity Is not plainly evident, it is appropriate to treat only the infringement issue. Lockwood v. Langedorf United Bakeries, Inc., 324 F. 2d 82 (9th Cir. 1963).

 See findings 31a-f. Contrary to plaintiff’s contention, tlie General Electric work was not abandoned, suppressed or concealed. Its work in 1964, although it did not result in a battery of a character suitable for commercial use, was sufficient to demonstrate operativeness. Its continued work throughout the latter part of 1964 and early 1965, its periodic reports to its customer, the prompt filing of a patent application when the project was concluded, the subsequent papers it published, and its attempt to sell the battery to the Marine Corps, negate the contention that G.E. abandoned, suppressed or concealed the battery. International Glass Co. v. United States, 187 Ct. Cl. 376, 408 F. 2d 395 (1969).0

 Claim 1 is as follows :
.. “An improved metal-air or metal-oxygen electrochemical cell containing a gas permeable envelope cathode comprising a hydrophobic polymer membrane and a conductive catalytic coating on the inner surface of said membrane, a replaceable metal anode positioned within said envelope cathode, an electrolyte in the space separating the cathode and anode, and means for retaining said anode in said envelope cathode and permitting its ready removal.”

 Claim 19:
“The method of generating electricity employing a metal/air or metal/oxygen electrochemical cell haying a replaceable and consumable metal anode positioned within a gas permeable nonconsumable envelope cathode comprising a hydrophobic polymer membrane and a conductive catalyst layer on the inner surface of said membrane and an electrolyte separating said anode and cathode, said method comprising the steps of discharging said consumable metal anode by applying a load to said electrochemical cell, removing the discharged anode from said non-consumable [sic] envelope cathode and inserting a fresh or charged anode into said envelope cathode,”

 Claims 1, 3, 8, and 9 are la Issue and provide as follows:
“1. An Improved metal/air or metal/oxygen electrochemical battery comprising a plurality of electrochemical cells each containing an envelope cathode comprising a hydrophobic polymer membrane and a conductive catalytic layer on one major surface of said membrane, said one major surface comprising the Inner surface of said cathode, a metal anode positioned within said envelope cathode, and an electrolyte In the space separating the cathode and anode, Intercell spacer elements between adjacent cells, said spacer elements having openings therein to permit access of gaseous oxidant to said envelope cathodes, at least one of said spacer elements being arranged in said battery In such manner that said oxidant contacts at least one surface of at least two of said envelope cathodes only through the openings In said spacer elements.”
*****
“3. The improved ‘battery of claim 1 including means for retaining said plurality of cells and said intercell spacer elements In operable structural association comprising an outer casing having openings therein to permit access of air or oxygen to the envelope cathode.”
*****
“8. The improved battery of claim 1 wherein the electrolyte of the electrochemical cell is trapped In a matrix.”
“9. The Improved battery of claim 8 wherein the metal anode is zinc, the hydrophobic polymer membrane of the envelope cathode is polytetrafluoro-ethylene, and an alkaline hydroxide electrolyte is trapped in a paper matrix.”

 See n. 9, supra.

 Previous to these contracts, plaintiff had acquired the rights to the Bacon technology which, In the early 1960’s, had the highest theoretical current density of any known fuel cell.