known by the Name of Turquoise. 907 
E. The portion dissolved by the potash was also calcined, 
and weighed 82 parts. 
F. Bein desirous of knowing if the Hquor in the experi- 
ment D contained any lime in solution, we poured carbo- 
hate of ammonia into it; a precipitate was obtained which, 
when dried and slightly heated, was found to be carbonate 
of lime ; its weight was eight parts, 
G. The liquor floating above was afterwards evaporated, 
but no precipitatewas formed; which led us to conclude that 
it contained no magnesia, 
H. Being persuaded that the precipitate E contained phos- 
phates, it Was treated with the sulphuric acid. The sub- 
stance was afterwards washed; and the washings being col- 
lected, prussiate of potash was poured into thems which 
formed a precipitate of a deep blue, the weight of which, 
after calcination, was one part and a half: it was red oxide 
of iron. (Care must be taken to heat the liquor, in order 
to separate the precipitate entirely.) 
The liquor floating above held in solution acid phosphate 
of lime; this was ascertained by obtaining phosphorus from 
it by the help of charcoal. 
I. this oxide of iron was again made red hot with a little 
pure potash. The matter assumed a deep green colour; the 
cooled mass was afterwards dissolved in water, which as- 
sumed the same colour. A little muriatic acid was added, 
and it then became of a fine rose colour. This experiment 
was repeated upon several turquoises, and the phenomenon 
always took place; which evidently proves the presence of 
a very small quantity of manganese. 
K. Wishing to ascertain if turquoises contained any phos- 
phate of magnesia, as the experiments of Messrs. Fourcroy 
and Vauquelin upon bones might lead us to think, I treated 
this substance in the manner pointed out by these chemists 
(Annales de Chimie, tom. xlvii.*), and the result was, that 
100 parts of turquoise contained two parts of phosphate of 
magnesia, 
* For M. Fourcroy’s abridgmeiit of this paper see Philosophical Maga- 
wane, vol. xxiv. p. 262. 
Pg It 
