ye 
1877.] 123 {[Genth, 
As it was an impossibility to pick out the volborthite, the whole mass 
was crushed, merely to separate the grains of the conglomerate. These 
being very little acted upon, the mixture was treated with very dilute 
nitric acid, which dissolved the vanadate, and left the bulk of the con- 
glomerate almost untouched; the latter was thrown on a tared filter, 
washed, dried and weighed. The amount of water in-it was afterwards 
determined by ignition. In a separate portion of the mixture the total 
amount of water was also determined. 
Different quantities gave 81.49 and 88.43% of insoluble residue, with 2.18 
and 2.15 water. The total water was found in one sample to be 6.30%, 
and the ignited insoluble residue 88.74%, which would give for the not 
ignited residue 85.55%, and 14.45 soluble substances with 4.49 water or, 
31.09%, which is a close approximation to the real quantity in the soluble 
portion. 
The results of the analyses of the soluble portion, to which I add the 
calculated percentage of volborthite corresponding to the formula given 
below, are as follows: 
il Jute Calculated. 
Si,O, = 1.38 = 1.36 = —— 
Al,O; a 4,45 — 4.7 = —— 
Fe,O, == iS — 0.45 — —— 
MgO — 3.01 — 1.42 — — 
CuO SAA: — Bishi — 38.41 
CaO = 4,29 — 4.49 — 6.77 
BaO — 4.29 — 4.30 _ (a Alg/ 
NEOR S= 133 (5 — 13.59 — 19.63 
H,O (by diff.) = (83.15) — [31.60] — 29.02 
100.00 100.00 100.00 
Considering silica, alumina, ferric oxide, magnesia and a portion of the 
water as impurities, and assuming the Woskressenskoi volborthite to be a 
combination of vanadates of barium, calcium and copper, with hydrate of 
copper and water of crystallization, we arrive at the following formula, 
closely agreeing with the analyses : 
Volborthite = (4 Ba 2 Ca 4 Cu), V, O, + 3 Cu H, O, 4 12 H, O. 
It will be seen that volborthite is closely allied to psittacinite (Am. 
Journ. Sc. [3] XII., 36), the formula of which I give for comparison : 
Psittacinite = 2 (2 Pb 3 Cu), V, O, + 3 Cu H, O, + 6 H, O; 
the difference being that the latter mineral contains twice as much R, V, O, 
and half as much water of crystallization ; and lead in the place of barium, 
calcium, and a portion of the copper. 
UNIVERSITY OF PENNSYLVANIA, 
PHILADELPHIA, August Ist, 1877. 
