Te aa eC Se ae ee ES SO ID EN ee ED ee REE EE ee ee ee ee we Reta te ee 
Pepe er 
Potassium as an Oxydizing mixture, 191 
Estimation of Sulphur in Organic Compounds ; by A. H. 
PEARSON. 
It is easy to determine sulphur in non-volatile organic com- 
pounds by oxydizing the substance with chlorate of potassium 
and nitric acid, precipitating the sulphuric acid as sulphate of 
barium and washing the latter with a solution of acetate of 
ammonium, to remove any nitrate of barium which may 
have adhered to it, 
To oxydize the sulphur compound, place a weighed quan- 
tity of it in a porcelain dish, pour upon it three or four table 
*spoontulls of strong nitric acid (39° B.), free from sulphuric 
acid, and add to the acid half a teaspoonful of chlorate of 
potassium. Cover the mixture with an inverted glass funnel, 
the stem of which has been bent to a right angle. Place the 
dish on a wire gauze support and heat its contents. From 
time to time lift the funnel slightly and throw a small frag- 
ment of chlorate of potassium into the hot acid. 
The funnel must be of such size that its rim may fall within 
the rim of the dish and rest securely upon the sides of the 
dish, above the liquid; it serves to retain the particles of 
liquid which are thrown up from the dish by the gas evolved 
during the decomposition of the chlorate. : 
The oxydation will be completed more or less rapidly ac- 
cording to the character of the substance operated upon. 
Only five or ten minutes are required to completely oxydize a 
third of a gram of sulphocyanid of potassium, while from 
half to three quarters of an hour are needed to destroy the 
same weight of ordinary free sulphur. It may be observed in 
passing, that sulphur which has just been distilled dissolves 
twice as rapidly in a mixture of nitric acid and chlorate of 
potassium as sulphur which has long been exposed to the air, 
Several samples of sulphocyanid of potassium, oxydized in 
this way, gave the following results :— 
A. 02015 grm. of- the sulphocyanid gave 0°5114 grm. of sulphate 
A. 0-265 sree of the sulphocyanid gave 0°6547 grm. of sulphate of 
B. joup ee af ha sulphocyanid gave 0°3796 grm. of sulphate of bari- 
B. 0-013 fam of the sulphocyanid gave 0°03 grm. of sulphate of ba- 
C. o-101 gem of the sulphocyanid gave 0-2387 grm. of sulphate of 
D. Prt of the sulphocyanid gave 0:067 grm. of sulphate of ba- 
rium 
D. 
“TD grm. of sulphocyanid gave 0-204 grm. of sulphate of barium. 
I). 
