ANALYSIS OF CHROLMAT£ OF IRO#. ~£ 



mixed with earthy matters. On some parts of its surface 

 the specimen exhibits green spots, which may be known for 

 oxide of crorae. Its specific gravity supports the opinion of 

 its greater purity. That of the specimen is 4'0579, while 

 that of the mineral of the Var is only 4'032(5. This differ- 

 ence in the gravity indicates of course a difference in the 

 proportions of the metallic matter contained in these two 

 varieties, and this the analysis proves. 



From the experiments related in the paper, which are too Component 

 long to be inserted here, it follows, that the Siberian P aTts of the 

 mineral contains, in 100 parts, f^ Ti&a Inine ' 



Oxide of chrome 53 



iron • • * 34 



Alumine 11 



Silex • 1 



t 



99. 



These results differ a little in the proportions from the andoft ^ 

 following obtaiued from the mineral of the Var by Mr. French. 



Chromic acid 43 



Oxide of iron 34 



Alumine • • • 20 



Silex 2 



99. 



Does chrome exist in the state of acid, or in that of oxide, They are p«>* 

 in the mineral called chromate of iron? Mr. Godon de ^bly aotchn* 

 Saint-Mesniin, in a paper on the artificial combinations of j, u t com- " 

 chromic acid, is inclined to think, that it is in the state pounds <if the 

 of oxide. Mr. Vauquelin, in his report on that paper, a nd of chrome! 

 appears disposed to adopt the same opinion. Mr. Laugier 

 agrees in it, and supports it by the following reflection. No 

 direct experiment proves, that chrome is in the acid state in 

 the native chromates of iron ; and we have so much the less 

 reason to think it, as slightly calcining the green oxide of 

 chrome with caustic potash is sufficient, to convert it almost 

 immediately into an acid: it is quite as probable therefore, 

 that chrome is in the state of oxide in the minerals of the 



Var 



