Rcz'iczo of Recent Geological Literature. 379 
sorption of heat," is made a basis principle of the discussion; and the 
contrasts of the upper and lower zones of the earth's crust resulting 
from this law and the natural antagonism of heat and pressure are 
traced out in hydration, the mutual replacements of oxygen and sul- 
phur, carbon dioxide and silicon dioxide, and the tendency to develop 
in the upper zone minerals of lower specific gravity with consequent 
expansion of the rocks, and in the deeper-seated zone minerals of 
higher specific gravity, with consequent 'contraction of the rocks. In 
both the' physical, and chemical categories, alike at lesser and greater 
depths, water is recognized as the one important and essential, me- 
dium of alteration; and an almost inappreciable proportion of water 
is regarded as sufificient foi" extensive and rapid metamorphism, in 
which it may act solely as agent, suffering neither gain nor loss. In 
this connection the author cites the experiments of Barus, according 
to which i8o°C. is a critical temperature for the solution of glass in 
water, the action being very slow below this temperature and aston- 
ishingly rapid above it. The solution of the glass and crystallization 
of its derived minerals are essentially contemporaneous and continu- 
ous processes, involving, in the absence of hydrous derivatives, no 
necessary diminution of the water, which may continue its work as 
a mineralizer indefinitely and so rapidly as to dissolve and deposit in 
crystalline form a volume of glass equal to that of the water in about 
half an hour, from which the author calculates that, even if the rate 
for rocks be only one-thousandth that for glass, a rock formation 
could be dissolved and crystallized 50,000 times by one per cent, of 
water in a mountain-making period of 150,000 years. w. o. c. 
Mineralogical N^otes. By C H. Warren. (Am. J. Sci., ij6, 1 16-124.) 
This paper describes: i. Melanotekite. a basic silicate or iron ses- 
quioxide and lead, from Hillsboro, New Mexico, the analyses of ex- 
ceptionally pure material indicating for this species and Kentrolite. 
the corresponding basic silicate of manganese sesquioxide 
and lead, the formula Fe4(Mn4)Pb3Si30,5. instead of Fe2(Mn2)Pb2 
Si- O9 heretofore accepted. 2. Pseudomorphs after phenacite, from 
Greenwood, Maine, in which gigantic crystals up to twelve inches in 
diameter having the form of phenacite have been completely replaced 
by a mixture of quartz and cookeite, with not a trace of beryllium re- 
maining. 3. Similar pseudomorphs after large crystals of topaz from 
the same locality. 4. Crystallized tapiolite (tantalate of iron and 
manganese) from Topsham, Maine, which is distinguished by its tet- 
ragonal form from its orthorhomic dimorph, tantalite, and by its com- 
position from the corresponding dimorphous niobates, mossite and co- 
lumbite. 5. Crystallized tantalite from Paris, Maine, which is shown 
by its very high specific gravity (7.26) not to be columbite, while the 
absence of manganese adds to its chemical interest. 6. Cobaltiferous 
smithsonite from Boleo, Lower California, which had been mistaken 
for the rare hydrated cobalt carbonate, remingtonite, but which is 
found by analysis to contain 39.02 per cent, of ZnO and only 10.25 
per cent, of CoO. w. o. c. 
