108 MANGANESE AND COBALT, OR NICKEL. 



of ammonium, saturated with ammonia, and the man- 

 ganese precipitated by phosphate of soda. After igni- 

 tion the precipitate consists of 2MnO, P0 5 . 



A more accurate, but still not absolute separation, 

 may be effected by neutralizing the solution of the 

 chlorides with ammonia, precipitating the metals by 

 sulphide of ammonium, and mixing the solution with 

 an excess of very dilute hydrochloric acid, when the 

 sulphide of manganese is dissolved with great facility, 

 whilst the sulphides of nickel or cobalt remain, undis- 

 solved. 



This method of separation is perfectly exact if the 

 sulphides be used which were formed at a high tempe- 

 rature. The oxides are precipitated at a boiling heat 

 by carbonate or hydrate of soda, the precipitate ignited 

 and weighed, and then heated to dull redness in a cur- 

 rent of sulphuretted hydrogen, in a porcelain boat, 

 placed in a porcelain tube. When cold, the porcelain 

 boat is put into very dilute hydrochloric acid, which 

 dissolves the manganese only, and leaves the sulphide 

 of cobalt or nickel behind. The conversion of the 

 oxides into sulphides may likewise be effected by 

 fusing them in a porcelain crucible with 3 times their 

 weight of carbonate of soda and as much sulphur, 

 after which the mass is treated with dilute hydrochloric 

 acid. 



Or nitrite of potassa is added to the concentrated 

 solution of the three metals, which precipitates the 

 cobalt as in No. 65. Acetate of soda is added to the 

 filtered solution, and chlorine gas passed into it, when 

 all the manganese is precipitated as superoxide. The 

 nickel and iron remain in solution, but the cobalt is 

 precipitated with the manganese. 



