of obtaining -pure Salts of Manganese, W5 



have a very small portion of carbonate of manganese remain- 

 ing with the precipitated peroxide of iron. The filtered so- 

 lution will now contain nothing but hydrochlorate of soda 

 and hydrochlorate of manganese, and from it the pure car- 

 bonate of manganese may be obtained as before. 



A slight modification of this process may be made if we 

 require at once a pure hydrochlorate of manganese free from 

 all salts of soda or potassa. Add to the compound solution, 

 freed from excess of acid by partial evaporation and resolu- 

 tion, some carbonate of manganese, enough to replace the 

 peroxide of iron ; boil for some time, filter, &c. : or, if the 

 operator have no carbonate of manganese, take a portion of 

 the liquid apart, precipitate by carbonate of soda all the iron 

 and manganese, and wash well ; then remove the still wet 

 mass from the filter, consisting of carbonate of manganese and 

 peroxide of iron, add this to the remaining liquid and boil,^ 

 when, as before, the rest of the iron will be precipitated and 

 replaced by the manganese. Of course the portion of liquid 

 which must be precipitated apart depends upon the relative 

 quantities of iron and manganese in the solution, and on the 

 quantity of free acid : in my experiments -^-q of the solution 

 was sufficient to furnish enough of the precipitate to effect the 

 entire purification of the remaining ^g ; but I had removed 

 nearly all excess of acid by evaporation. 



This process is peculiarly adapted to the purification of a 

 solution of hydrochlorate of manganese containing only a 

 trace of iron, saving thereby the trouble of evaporating the 

 whole of the liquid and igniting: thus, I found in one of mv 

 trials that I had four pints of a strong solution of hydro- 

 chlorate of manganese containing only a trace of iron ; the 

 evaporation of all this to dryness and igniting would (seeing 

 it contained more than a pound of hydrochlorate of manga- 

 nese,) have been a very long and tedious operation, but by 

 adding a few grains of carbonate of manganese, and boiling 

 for a quarter of an hour, it became quite pure. 



It must be borne in mind that the success of these methods 

 depends entirely on the iron being strictly peroxide : should 

 any protoxide be present, this must be peroxidized by the 

 addition of nitric acid. 



I find that carbonate of manganese free from iron can also 

 be procured from the liquid obtained, on dissolving the mass 

 left after procuring chlorine by common salt, oxide of man- 

 ganese, and sulphuric acid,— by the method. No. 2. 



Hence, the dyer, potter, or glass-maker can now have, at a 

 trifling expense, all the preparations of manganese chemically 

 pure ; and the absence of iron is of much importance in many 

 of their applications in the arts, a subject which has for some 



2C2 



