190 GEOLOGICAL RECONNOISSANCE 
tate is considerable, it has to be dissolved in hydrochloric acid and precipi- 
tated with carbonate of soda]. 
V. To the filtrate some hydrochloric acid is added, and heat applied until 
the odors of chlorine and acetic acid have disappeared; the lime is then 
precipitated with oxalate of ammonia, and from the filtrate the magnesia 
with phosphate of soda. 
DOLOMITE, 
Containing: Insoluble silicates; carbonates of lime, and magnesia; sesqui- 
oxide of iron with trace of manganese; alumina, potassa. 
I. The mineral is dissolved in hydrochloric acid, solution evaposated to 
dryness, residue treated with water acidified with hydrochloric acid, and 
insoluble silicates and silica collected on filter. 
Il. To the filtrate a little chlorine water is added, to oxidize the man- 
ganese, then precipitated with ammonia; the precipitate, containing all 
the iron, alumina, and manganese, and a little lime and magnesia, is re- 
dissolved in hydrochloric acid and again treated as above. This precipi- 
tate is free from the alkaline earths. It is dissolved in hydrochloric acid 
and the solution divided into 2 equal portions: 
In the first portion iron plus alumina are determined by ammonia; 
In the second portion the iron alone is determined by chameleon mineral. 
Ill. The two filtrates, and washings, are united, and about 4th of the 
liquid used for the determination of lime by oxalate of ammonia, and that 
of magnesia by phosphate of soda. . 
IV. For the determination of the alkali a fresh portion of the mineral 
is treated with repeated portions of boiling acetic acid; the filtrates are 
united, evaporated, transferred to a platina capsule, and ignited until the 
empyreumatic odor of decomposing acetic acid disappears; the residue is 
exhausted with boiling water, the liquid mixed with some oxalic acid, 
evaporated to dryness, ignited; the residue is again treated with boiling 
water: the filtrate contains the potassa as carbonate; it is converted into 
chloride, ignited and weighed. 
DETERMINATION OF NITRIC ACID. 
To ascertain the quantity of nitric acid in the nitre earths subjected to 
analysis, I proceeded as follows: 
100 grammes of the earth are pulverized, and digested over the water- 
bath with repeatedly renewed portions of distilled water until all the 
soluble constituents of the earth are taken up by this liquid. The solution 
