uadzgsete 
—— 
‘ Scheerer on Isomorphism. 193 
to exist between the forms of the crystals of these two minerals, 
would be thus farther borne out. According to Kersten’s analy- 
sis of the cobalt bloom from debitesbens! the “entitle for this min- 
eral is however, Co® ‘As +SH. 
C. Arseniates of Copper. 
1. Olivenite. 
Richardson found the erystallized olivenite to consist of— 
39°9 
rsenic acid, : : 39°80 
Oxyd of Souper, ' oe 56:2 = 56-65 
Water, ; , 3:9 3°55 
100-00 
The mean oxygen ratio from these two analyses is— 
igs ; mp te (Cu)s ma 
This too is the formula of vivianite and of the other minerals 
cited. It is assumed that 2H = 1Cu. 
2. Euchroite. 
The euchroite from Libethen consists, according to Turner, of 
arsenic acid 32-02, oxyd of copper 47°85, water 8:80 = 99-67 
From this the following oxygen ratio may be deduced, 11-47 As 
: 12-00 (Cu) : 12-01 H, approaching very closely the ratio calcu- 
lated for phosphorochalcite, and whence may be deduced the for- 
mula, (Cu)? As+5H. In euchroite however, a larger portion of 
the water (about one-fourth of the whole amount) plays the part 
of a base, than is the case in phosphorochalcite. 
3. Copper-foam 
According to v. Kobell’s analysis, the Seyile of the diverging 
foliated copper-foam from Falkenstein, is Cus As+ 10, not ta- 
ing into account the quantity of carbonate of lime therein con- 
tained, the amount of which approaches 1 atom. 
4. Erinite. 
From 'Turner’s approximative analysis of this mineral, its con 
stituents are arsenic acid 33-78, oxyd of copper 59:44, water 5 01, 
alumina 1:77 = 100-00. Neglecting the alumina, this gives the 
following oxygen ratio, 11-73.As : 11-99Cu : 4-45, whence 
may be deduced the formula, 2Cus As+5H, or perhaps rather, 
3Cu* As+5H, The former requires an oxygen. ratioof 11; 11: 
5:5,—the latter of 12: 12; 4, 
