"9 
? 
W. F. Hillebrand—Lillingite and other Minerals. 349 
must be proportionate to the amount of heat received from the 
sun, In proof of the erroneous nature of this assumption, I 
refer to the fact that on the lofty summits of the Himalayas 
and Andes, for example, the quantity of heat received from 
the sun would be sufficient to melt at least fifty feet of ice per 
annum, and that is no doubt more than ten times the quantity 
actually required to be melted; yet notwithstanding the snow 
Temains permanent. The cause of this non-melting I showed 
is due to the fact that at these elevations, owing to the dryness 
I was much pleased to find that Professor Newcomb has not 
only adopted these views regarding the effects of an absence of 
aqueous vapor, but suggested that they may yet afford an 
€xplanation of the cause of the Glacial epoch. Every one 
familiar with the subject, however, knows that that epoch was 
hot due to a dryness of the air, but the reverse. 
Arr. XLL— Communications from the U. S. Geological Survey, 
ltocky Mountain Division. VI. On an interesting variety of 
Liliingite and other Minerals; by W. F. HILLEBRAND. 
[Read before the Colorado Scientific Society, April and Dee., 1883.] 
AROUND the base of Teocalli Mountain, on Brush Creek, 
OU 
Gunnison Count , Colorado, there occurs, in several mines, 
te of such 
attention at a giance. 
€xcited, that a series of observations was.und 
the results are embodied in the following. : 
The precise locality of occurrence of the specimens examined 
was unknown to Mr. William McCree, who presented them to 
the Colorado Scientific Society, but Mr. J. G. Ridgley has ob- 
i as 
he northwest slope of Teocalli Mountain. : 
Ridley, associated with native silver, prous- 
