S. L. Penfield— Chemical Composition of Amblygonite. 299 
Montebras, A, 1°06: Auburn, 0°91; Hebron, A, 0:99; Paris, 1:02; 
Hebron, B, 1:18; Branchville, 0°97; Montebras, B, 1:05. Thi 
relation seems rather striking, and although it is not as simple 
as we should like to have it, or perhaps as plausible as the first 
theory, yet it may possibly be the correct one. hichever of 
these explanations is accepted, it will not materially alter the 
formula above made out for the minerals, the variation from 
which is too slight and not constant enough to be expressed by 
any different formula, It will be seen from analyses I and II 
that water is found in the Penig and Montebras varieties which 
thought it best to give my method of analysis in full, which 
and titrating the liberated hydrochloric acid with a standard 
alkali solution.* The varieties from Penig and Montebras are 
nitric acid, nearly neutralizing the excess of acid with ammonia, 
precipitating a 
way. 
To determine the bases, one gram was weighed into a large 
Platinum crucible, mixed into a paste with from two to three 
cubic centimeters of sulphuric acid, and heated, with the cruci- 
ble covered, over a low gas flame till not over a cubic centime- 
ter of sulphuric acid remained. The contents of the crucible 
. 
Were then rinsed into a platinum evaporating dish and treat 
* See Remsen’s American Chemical Journal, vol. i, No. 1. 
