110 Mr Magnus's Analysis of Picrosmine. 



The precipitate, produced by ammonia, when dried and ig- 

 nited, weighed 0.096 gr. or 4.477 per cent. It was dissolved 

 in muriatic acid, and then digested with an excess of pure po- 

 tash, in order to separate the soluble alumine from the inso- 

 luble oxides of iron and manganese, and the magnesia. The 

 alkaline solution of alumina, was rendered acid by muriatic 

 acid, and the alumina afterwards precipitated by carbonate of 

 ammonia. It weighed 0.017 gr. or 0.792 per cent. 



What had been precipitated by the potash, was dissolved in 

 muriatic acid, exactly neutralized with pure ammonia, and 

 the iron precipitated by means of succinate of ammonia. The 

 succinate of iron, after being well washed, was decomposed on 

 the filter with dilute caustic ammonia, in order to remove the 

 greater part of the acid. The oxide of iron, dried and ignited, 

 weighed 0.030 gr., equal to 1.399 per cent. 



The liquid, from which the succinate of iron had been se- 

 parated, as it did not contain any other substances but mag- 

 nesia and manganese, was evaporated ; the residue, completely 

 dried and ignited, in order to drive off the volatile salts of am- 

 monia, then dissolved in water, and added to the fluid obtain- 

 ed above, which likewise contained only magnesia and manga- 

 nese. The whole was neutralized with ammonia, and hydro- 

 sulphuret of ammonia was added to it, to precipitate the man- 

 ganese. Ignited, it weighed 0.010 gr., and as these may be 

 considered as a combination of the peroxide with the protoxide 

 of manganese, the proportion of sulphuret of manganese being 

 very small, there can be no perceptible error in supposing them 

 equal to 0.009 gr. of protoxide of manganese, or 0.420 per 

 cent. 



From the liquid still left all the hydro-sulphuret of am- 

 monia was evaporated, and the sulphur separated by filtration. 

 The remainder was dried and ignited, in order to get rid of 

 the sal ammoniac ; then redissolved in a small quantity of water, 

 and a few drops of sulphuric acid added. The sulphate of 

 magnesia, thus obtained, after being dried and exposed to a 

 slight red heat, weighed S.098 gr., corresponding to 0.715 gr., 

 or 33.348 per cent, of magnesia. 



In order to obtain any potash or soda which might have 

 been united to the latter substance, it was dissolved in water, 



