the Arseniates of Copper , and of Iron. 195 
numbered indiscriminately, for the very purpose of excluding 
prejudice ; and it was not till my task was ended, that we com- 
pared our observations. If I had been admitted into any previous 
knowledge of the arrangement dictated to him by the principles 
of crystallography, I should have been afraid, that I had 
merely thought true, what I wished to be so. But I can, most 
conscientiously, indulge in the satisfaction which the according 
results of different means to prove the same proposition na- 
turally excite ; and which is justly due to the truth of the out- 
ward marks, however delicate, yet still to be perceived, that 
nature has left visible to those who will observe her. 
I shall now proceed to offer the result of a chymical 
analysis, undertaken with a view to determine what confidence 
the crystallographical arrangement, adopted in the preceding 
Paper, might merit ; and to shew how far sciences so nearly 
allied, may receive new light and confirmation from reciprocal 
aid. 
I shall confine myself to detail only those general pro- 
cesses which, upon frequent trial, have been found preferable. 
By reducing to powder any of the arseniates of copper here 
spoken of, and then exposing them to heat in a platina crucible, 
the water of crystallization was quickly dissipated. But, as 
too great a degree of heat volatilized some portion of the 
arsenic * acid, it was found necessary to moderate the heat ; 
* There is no doubt that philologists, who do not consider the principles of the 
new methodical nomenclature, may, at first sight, think the term arsenic objection- 
able ; particularly as previous custom and analogy had given another denomination, 
arsenical , which is the natural adjective of the substantive arsenic. They may say, 
that the difference of accentuation alone marks the distinction between the substan- 
tive and the new adjective. But every chymist will set the weightier considerations 
of method and order before such objections. In French, the termination in ic, for 
C c 2 
