Seybert’s Analysis of Chromat of Tron. 323 
#. To ascertain whether the proper quantity of acid was 
added to the liquor (£,) a portion of it was rendered slight- 
ly acid, and treated by ammonia ; no precipitate was form- 
ed; it was therefore certain, that the acid added had pre- 
cipitated all the alumine. The liquor was then treated by 
an excess of muriatic acid, it became intensely brown ; chlo-— 
rine was disengaged, and on heating the liquor, it was changed . 
io a beautiful deep green. The muriatic acid decomposed. 
the chromate of potash, and formed muriate of potash and - 
proto-muriate of chrome. The green colour proved that. 
the chrome was in the state of a protoxide. ‘The liquor, . 
treated by ammonia, yielded a light green precipitate of © 
proto-hydrate of chrome, which, washed and calcined, 
gave protoxide of chrome 1.79 grammes on 4.53 grammes 
of the mineral, or 39.514 per 100. j 
This chromate of iron, after being calcined, is constituted 
as follows. Per 100 parts. 
C. Silex, - 10.596 Containing oxygen, 5.329 — 
D, Per-oxide of iron, 36.004 - = - 11.038 
E. Alumine, 13.002 = Bs - 6.073 
&. Protoxide of Chrome 39.514 > a - 11.810 
99.116 
100.000 
000.884 Loss. 
During my residence in Paris, I examined, in the Royal 
School of Mines, a specimen of the chromat of iron, found 
in Chester county, Pennsylvania. In its external charac- _ 
ters, it did not vary materially from that found at the Bare 
Hills ; the result of the analysis was as follows, viz: 
Per 100 parts. 
Sileyeer - = 02,901 Containing oxygen 01.45 _ 
Peroxide of Iron, - 35.140 - - = 10.77. 
Oxide of Manganese, a Trace. 
Alumine, - — = - 09.723 - - - 04.54 
Protoxide of Chrome, 51.562 - - - 15.41 
99.326 
100.000 
000.674 Loss, 
