National Republican., 1883-04-18
Regular Meeting Of the Academy Of Sciences
at the National Museum.
Prominent Scientists Present From All
Parts Of the Country
An Interesting Paper on Mstallifercus Deposits and
Veins by Prof Joseph Le Oonts.
The other Papers Read and Those Who
Read Them.

were present Profs. Cleveland Abbe, Of this
city; Alexander Agassiz, Of Cambridge, Mass;
Spencer +. Baird, Of Washington, ID. O.;
George +. Barker, of Philadelphia; w. H..
Brewer, Of New Haven; John II. Coffin, U.
s. N, Edward ID. Cope, Philadelphia; Wal
colt Gibbs, Cambridge; Theodore Gill, Wash
ington Asaph Hall, U. s. N; Julius L. Hi.
gard, George w. Hill, and A. A. Hum
phreys, Washington; 8. Terry Hunt,
Boston; G. S. Pierce, United States coast
survey O. II. Il. Peters, Clinton, N. ";
John w. Powell, Washington; Rafael Pun.
pclly, Newport; Ira Remsen and Henry A.
Rowland, OF Johns Hopkins university; 8.
II. Scudder, Cambridge Benjamin Silllman
and A. Wright, of New Haven Gen. NJ. @.
Meigs, and Messrs William Ferroll and
Charles A. Schott Of this city. The first
paper read was one by Prof. Joseph LeConte
which in the authors absence was read by
Prof s. Terry Hunt. The paper said that
the phenomena Of metalliferous deposit by
solfatusic action at Sulphur Bank aud Steam
boat Springs have tended strongly to confirm
what he had previously believed to be the
most probable theory Of vein formation,
and at the same time TO give 1t moro clearness
and defniteness. The structure. the mode of
occurrence and the contents of metallifer-
Gus veins leaves no longer any room for
doubt that they have been formed by deposit
iEOn boluIlOnh. III any OOuDJ nHu DnReteu
on this subjec IL was thoroughly dissipAted
by the phenomena Of deposit still in progress
at Sulphur Bank and at Steamboat Springs.
Among metallic ores oinnabor has long been
considered possible exception to this mode
Of deposit, The extreme volatility Of this
sulphide, the extreme irregularity Of it's
veins, and its frequent occurrence in
the vicinity Of comparatively recent volcanic
action has suggested that IL may have
been deposited in irregular fssures cracks,
cavities, &C., by condensation of Its vapors
sublimod by volcanic heat beneath. But the
phenomena Of sulphur Bank and Steamboat
Springs ought TO settle the question forever.
Cinnabor as we'll as other metallic sulphides
are now being deposited there, along with
silica, from solutions. Admitting, then, as
established tho view that metalliferous veins
have been deposited from solutions, the most
difficult questions still remain What are the
conditions under which deposit takes place ?
and what, in addition to simple water, have
been the solvents?
In answering tho first question IL must be
remembered that the chemistry Of nature Is
far more subtle and refined than that Of tho
laboratory; that substances which arc ro-
garded as practically insouble In tho latter
cannot be so regarded In the former. Tho in
fnite patience Of nature and the infinite slow
ness OF her operations must be taken into ac.
count. In the perpetual circulation Of sub
terranean waters infnitosmal deposits, con
tinued and accumulated through almost inf
mite time, produce large results. Thus min
eral veins may bo composed of substances Of
EXTREMIST insolubility, and yet bo deposited
from solutions. In fact, such extreme insolu-
bility, or at least very feeble solubility, would
seem to bo O condition Of mineral vein forma-
tion, for otherwise tho minerals would be In
most casos brought to tho surface instead Of
being deposited below.
Again, 1t must be borne in mind that solu-
bility, even the feeblest, is notably increased
by heat, especially super heat, and by press
ure. The latter Is generally regarded only as
necessary condition Of super heat and not
as itself an active agent. But in fact pressure
acts directly as an active agent in increasing
the solubility OF nearly all substances Mr..
Sorby has not only proven this by actual ex-
pertinent on great variety ofsubstances, but
has shown that II is n necessary consequence
and beautiful illustration of tho law Of cor
relation and conservation Of natural forces,
and that wo have in this as in the case of
fusibility an example of tho equivalency of
mechanism and molecular forces. For, as in
the matter Of fusibillty in all cases in which
expansion takes place in fusion, pressure by
resisting expansion raises the fusing point,
while only in those exceptional cases
like ice, in which contraction takes
place, infusion, pressure by arresting
contraction, lowers the fusing point. So also
IN the matter of solubility, in all cases in
which contraction takes place in solution,
namely, in which the volume Of tho solution
is less than the combined volumes OF constit-
uents, pressure by arresting contraction in
creases solubility, while only In very excep-
Gonal cases rs, for example, sol ammoniac in
which expansion takes place In solution,
pressure by resisting expansion diminishes
solubility. These latter cases are 30 ex-
tremely rare that we may assume as o law the
increased solventpower Of water in proportion
nv ati-
mont thus to determine the mechanical equiv
alent of the chemical force of solution OF any
given substance; and, In fact, this has been SO
determined for several substances by Mr..
Sorby. There can be no doubt, then, that the
solvent power of water may bo In
creased without limit by corresponding
increase of heat and pressure 1t is
quito certain, therefore, that water deep
In the interior Of tho earth, especially
in volcanic regions, and therefore under
heavy pressure and super heat, would have
its solvent power greatly increased, not only
by the super heat but also by tho pressure
IL is believed that few substances could resist
entirely its solvent power. Such waters,
coming up slowly toward the surface through
assures large and small, would have their
solvent power diminished both by cooling
and by relief Of pressure, aud must OF neces-
sity deposit in their courses and form mineral
veins. But the solvent power of subterrane.
Gus waters is still further very greatly Ia.
creased for most vein matters by the pres
sure Of alkali in the form Of alkaline car
donates or alkaline sulphidOs, or both This
Is especially true Of the commonest Of vein
stufs, viz, quartz and limo carbonate, and
the commonest forms Of metallic ore, via,
metallic sulphides. The solubility Of EilieA
in alkaline carbonated waters Is well known,
and with excess Of oarbonio acid Ia
the waters all the earthly and metal
lie carbonates are also soluble
The solubility Of many and probably Of all me.
tallic sulphides in alkaline sulphides, espo.
cially with excess Of hydrogen sulphide un-
der pressure and super heat, can no longer be
doubted; for iron sulphide aud mercuric sui
phide are now being deposited from such
waters, both at Sulphur Bank and at Steam
boat Springs. Mr.. Christy and others have
proved the solubility Of mercuric sulphide un-
der pressure and super heat by actual expert
ment; and these are among the most insolu-
Bile of metallic sulphides 1t is certain, then,
that metallic sulphides are soluble TO limited
extent in alkaline sulphides, forming doubt
less double sulphides. IL is certain, also,
that the solubility Is increased by
super heat and pressure. II is therefore
also certain that hot waters containing aka
line carbonates and alkaline sulphides, circu-
lating at great depth and therefore under
heavy pressure, would take up silica, earthly
and metallic carbonates and metallic sui
phides, and that coming up slowly toward
the surface they would deposit these sub
stances in their COURSES partly by cooling and
partly by relief Of pressure, and thus form
metalliferous veins. Cooling and relief of
pressure are the most usual courses of deposit,