Arkansas true Democrat., 1858-03-09
the margin.

I'm I'm :. Lead Lead } 5s3 sSs ! D''@'s
 Other authors give other combinations, but the above are all that are necessary for purposes of illustration.
 Ii will be observed that the first two of these alloys melt at heat below that of boiling wa ter The first is known as Roses metal; the se- cond as Sir Isaac Newton's. Some wags ot che mists have amused themselves by presenting spoons made of Rose metal to their lady ac- ouaintaaces, and then marking the surprise of their fair friends on seeing their teaspoons melt in their tea-cups
 h the solder used by tin-snths and plum bers the leader has familiar example of flu sbe alloys"
 If we compare the melting points of comb- nations of tiu, bisrnuth, and lead with those of some of the other best known metals we will see that there is peculiar propriety ill denoml- mating them "fusbe alloys" According to BraIde, silver fuses at 1873 copper at 1,996 and gold at 2,2OO According to W. Henry, pure iron fuses at 2l,637, and platina at 23, IF. According to Kane, cast iron fuses at 2,786, "whle pure iron fuses at only the very highest temperature, and then becomes only semi-huid." Bral de does lot pretend to give the exact melting point of p!atina and some other metals, but is content 10 say that they fuse only through the action of the oxy- hydro gen blow pipe; or as he might have added, the voltaic battery.
 Taking advantage of the qualities which tin, lead and bi>muth have in their different com bnatons, and sometimes, 1t may be, mixing zine ard antmony with them. the French-no indifferent tchemists-have, for many years, used plates of these alloys as a preventive of steam explosions The use of such plates would, however, never be tolerated in America, where the rule is to prefer speed to safety for then every time the alloy melted it would be neces- sary to stop the boat and cool down the boiler till new plate could be inserted.
 Another mode of using the alloys is in plugs, or in open tubes in which the metal is exposed to the pressure of steam as well as its heat But then the tin and the bsmutb, the softer metals, are driven out, leaving only the lead which will not fuse at less temperature than 612 degrees. Such use of fusible alloys serves only to create false confidence.
 The plates not being adapted to the go ahead" propensities of the American people, and the objection which has just been stated, resting against the alloys when used in the form of plugs or ill open tubes, Ii remains to be seen whether there is any other way in which they can be app lied so as ito provide for the greater safety of passengers on board of vessels propelled in whole or in rart by steam.'
 We believe that there is and that fus. ble alloys when applied on the plan devised by the late MT. CadwalIader Evans of PittslArgh, Penn. are provided they are properly prepared, among the most effective preventiyeS of steam boiler explosions. h his "slfety guard" the fusible alloys are enclosed in tight metallic box, to exclude the pressure of the steam, and leave only the heat to operate on them. This prevents the tin and the bsmuth from being driven out, which is almost sure to be done when the alloy is applied in the form of plugs, or of open tubes. Alloys employed on MT. Evans plan, can be used for years in suc- cesson, and not require renewal
 But this is not the only excellence of his in vention. When the alloy mets spindle turns and by its action promptly opens safety valve of such dimensions to let the steam escape in sufficient quantities to afford relief Thus the heat of the boiler, when it reaches the melting point of the alloys, is made the means of preventing the direlul consequences that must ensue from any further increase of heat.
 Notifications may be made of Mr. Evau's Safety Guard; bnt on no other principles than those he has adopted, can fuSible alloys be so applied as to answer the end of the steamboat act of 1852, that is, to provide for the greater safety of passengers on board of vessels pro- peled in whole or in part by steam"
 h a small work we have now before us, the excellence of Mr. Evans plan, is attested by some of our most distinguished scientific men, as, for example, the late Dr. John Locke, Pro- lessor of Chemistry, in the Ohio College, Gin cinnat, Professor Henry, of the Smithsonian Institute Washington city Professor Renwick, of Columbia College, N. r., Professor McCul- louch, of Princeton College, N J., Professor OImstead and Professor Slliman of Yale Col lege, Connecticut
 Its excellence is further attested by Col Long, of the U. s. corps of typographical engineers, by NIT. Ellis, the late chief engineer of the navy yard at Washington city, by C. C. Has well late engineer in chief of the Unified States Navy, by the late Dr. Thomas P. Jones. the scientific editor of the Journal of the Franklin Institute, and by Edmund Burke, former Com missioner of Patents.
 It is also attested by the principals of various steam engine manufactures as, for example. by firms in Boston, Mass, ? in Providence, \. J., g in New York, II in Philadelphia, 15 in Pittsburgh, 2 ill Wheeling, in Cincinnati, and in Louisville And, finally it is a,tested by more captains and engineers of steam-boats than we can at present conveniently enumerate.
 A writer in the Washington Globe of Dec. 15, 1856, bears the following testimony:
 "I have made particular inquiries into the subject Evans Safety Guard has now been in operation some sixteen years, and on some hundreds of boats; and I could never hear of more than four such boats on which fatal acci. dents had occurred. It was distinctly proved that on two of those boats the safety valve was tied down. The third boat was proceeding under pressure of 1S0 pounds, higher pres sure than any engineer ought to attempt to carry. What the circumstances of the fourth boat were, have never been able to learn".