Dr. Genth’s Contributions to Mineralogy. 425 
, 8 
Insoluble, - 1 0-48 p.c. 
hlorine, ‘| * not determined. 004 * 
nic acid, - not determined, 1:98 “ contains oxygen 144 
Phosphoric aci 18°74 1974 -* € * 10:50 
Oxyd oflead, - notdetermined. 2904 « id 8 211 
Alumina, ~ 69 26:54. * * ai 11°91 
Sesquioxyd of iron, 068 0-90. * . - 027 
lime,© - — - 149 144 “ “ # 069 
Water, cea 21°65 . 2086 “— * “ © 1055 
99°02 
Deducting 0°72 of oxygen of bases RO for the quantity of car- 
bonic acid found, and considering the carbonate as an impurity, 
the oxygen ratio of PbO: AlzO3s(Fe2O:): POs : HO 
18 equal to 208 : 12°18 : 10°50 : 18°55 
or equal to the atomic ratio of 2 : Sige Bee | 
corresponding with the formula 
8PbO, POs +3Al120s, 2P0s+3(Al202, HO)+24H0. 
The calculated percentage of the pure mineral is therefore: 
3PbO, 3348 30-44 p.e. 
AlpOs, . 308-0 2801 « 
3POs, | : " 2140 1946 “ 
27HO, - : - - 2430 22:09 * 
10998 100°00 
14. Lanthanite. 
have to add only a few remarks to the investigations of Mr. Wm. 
P. Blake (Amer. Jour. Sci., xvi, 228) and Prof. James L. Smith 
If. 
Lanthana (with oxyd of didymium), — - phen 54°83 
Carbonic acid, - ~ ee cate ies ta te —_ 
Water (from the loss), - - - —— 
as > as- 
improbable, however, 
SECOND SERIES, VOL. XXIII, NO. 69,——MAY, 1857, al “ 
a 
