384 M. Austin— On the estimation of Manganese. 



Mn 3 4 MnS0 4 



MH4CI 

 grm. 



Found. Theory. Error. Pound. Theory. Error, 



(i) 10 0-2463 0-2478 0'0015— 0'4903 0'4905 0*0002 — 



(2) 10 0-1110 0-1121 0-0011— 0*2225 0-2219 0*0006 + 



(3) 10 0-1584 0-1581 0-0003 + 0'3126 0*3128 0-0002 — 



(4) 10 0-1672 0-1699 0'0027— 0'3355 0'3364 0'0009 — 



By treatment of the filtrates of (1), (2) and (3) with bromine 

 and ammonia at boiling temperature no manganese was found. 

 In the filtrate from number (4) by the same treatment, a small 

 amount of manganese dioxide was precipitated, which when 

 heated with concentrated sulphuric acid gave 0-0006 grm. of 

 manganous sulphate ; and, hence, the error in that determina- 

 tion is really 0-0003 grm. on the sulphate. The slightly larger 

 deficiency recorded in the table was probably due to imperfect 

 filtering. 



It seems to be evident that Guyard's method of separation of 

 manganese as the manganous carbonate, when handled with 

 precautions, gives complete separation of that element. It 

 must be recognized clearly, however, that the precipitation 

 should be made in the presence of a considerable amount of 

 ammonium chloride, and that great care must be used in the 

 filtering and washing of the finely divided precipitate. It is 

 altogether preferable to weigh in the condition of the sulphate. 



In conclusion thanks are hereby expressed to Professor F. A. 

 Gooch for kind assistance. 



