230 W. P. Blake on Crystallized Carbonate of Lanthanum. 
one-hundredth part of nitric acid, it will be slowly but completely 
dissolved, an evidence of the absence of cerium. As to the pre- 
sence of didymium, it was only indicated by the color of the 
oxyd ; the quantity of the mineral was too small to enable me to 
decide in any way as to the amount of that substance mixed with 
the lanthanum. 
A quantitative examination, in which every thing was estimated 
directly, gave, 
Water, - - . - 24:09 
Carbonic acid - - - 22:58 
Oxyd of lanthanum and didymium, * 54:90 
10157 
The excess in the analysis is due to the peroxydation of a por- 
tion of the oxyds; but as we are not yet possessed of any accurate 
method of reducing them, the analysis must stand as it is. Other 
analyses were made of the separate constituents, the results of. 
which accord with the above, and give the formula, Lad+3H, the 
per-centage of which is water 25-95, carbonic acid 21-11, oxyd 
lanthanum 52:94= 100-00. 
This carbonate is the artificial carbonate commonly obtained 
by adding the alkaline carbonates to a soluble salt of lanthanum.” 
I have obtained the following per-centage weights, for the 
separate constituents. 
La 6G CHF (by ign. 
L 54-27 19-13 SSK es 
IL. 54-93 Bs 45-07 
lL 54-64 45-36 
Another determination of carbonic acid gave 19-936 p.c. Sub- 
tracting the mean of the two determinations of carbonic acid from 
the loss by ignition gives, 25-68 per cent. as the amount of water. 
These results are sufficient to show that the mineral is a simple 
carbonate of lanthanum with three atoms of water, and I prefer 
to describe it as Lanthanite, although its composition is very 
different from that given by Mosander to the mineral found at 
Bastnas in Sweden, which has been examined in small quantities 
only, and possibly in a state of admixture, so that considerable 
doubt as to its constitution seems to exist ; it is now important 
that it should receive a reéxamination as it very probably has 4 
composition corresponding with the mineral just described. 
The occurrence of carbonate of lanthanum almost chemically 
pure with zinc ores in limestones of silurian age, is a fact of no 
small interest. It should be remarked, however, that the lime- 
stones have decomposed to a considerable depth, and left the fine 
ore, together with peroxyd of iron and manganese, in the soil; the 
uanthanite was only six feet below the surface. 
New York, March 1853. 
