272 Professor Gmelin's Analysis of Helvine. 



subcarbonate of potash. The oxide of manganese weighed after 

 ignition was 0.865 gr. =0.77945 gr. of the protoxide =40.449 

 p.c. In case that the sulphur of Helvine is combined with man- 

 ganese to a sulphuret (which is very probable, the iron being 

 at any rate not sufficient to saturate the sulphur), from the 

 0.77945 gr. of protoxide of manganese, 0.22076 gr. (corre- 

 sponding to 0.17233 gr. of metallic manganese, which satu- 

 rate the 0.097442 of sulphur) must be deducted. There re- 

 main, then, 0.55869 gr. protoxide of manganese =2 28.993 p. c. 

 and the whole quantity of protoxide of manganese amounts to 

 31.817 p- c. At the same time we obtain for the sulphuret 

 of manganese 0.26977 gr. = 14.000 p. c. 



f. The alkaline lixivium, separated from the brown precipi- 

 tate (in d), was supersaturated by muriatic acid, and the li- 

 quid then thrown down by a small excess of carbonate of 

 ammonia. A white earth fell down, which, after ignition, 

 weighed 0.1988 gr. = 10.161 p. c. The liquor separated by 

 the filtre from this precipitate deposited after some time a 

 white precipitate ; it was, therefore, evaporated together with 

 the wash-water, and the precipitate collected upon a filtre. 

 It weighed after ignition 0.036 gr. e= 1 .868 p. c. As it was 

 found afterwards, that this precipitate, and the earth already 

 mentioned, were one and the same substance, the whole quan- 

 tity of the earth obtained amounts to 12.029 p. c. 



gi 1.039 Grammes of Helvine left after ignition 1.027 gr. ; 

 100 p. would therefore lose 1.155 p. c. 



The nature of that earth is established by the following ex- 

 periments : 



It is not changed before the blow-pipe, nor does it become 

 yellow by heating. It is dissolved by borax and salt of phospho- 

 rus in large quantity, and yields a clear glass, which becomes 

 milky by flaming ; by a large addition to these fluxes, the 

 glass becomes milky by itself when cooling. It is not acted up- 

 on by soda, nor is there formed a white ring surrounding the 

 assay ; when heated with nitrate of cobalt, a blackish grey mass 

 is obtained. The solution of this earth in acids is thrown 

 down by carbonate of ammonia, the precipitate is almost entire- 

 ly dissolved by an excess of it, leaving behind a little alumine 

 not perfectly pure, forming alum with sulphuric acid and pot- 



4 



