96 W. G. Mixter—Estimation of Sulphur in Coal. 
tube to complete the oxidation. In No. 12 a small platinum 
tube, extemporized from foil, closed at one end by a glass plug, 
was employed. 
The pulverized tobacco of No. 13 was burned in an open 
tray, and the combustion occupied less than five minutes. A 
small amount of hydrocarbons passed over unconsumed, and 
owing to the intense heat a white sublimate formed above and 
senius has conclusively shown in a late paper.t This method 
of ao the barium ee has 8 the sanction of 
t is not probable that barium bromide would resist 
treatment which removes the chloride. In the analyses given the 
writer added barium chloride slowly to the concentrated boiling 
solution, and after twelve hours or more decanted the 
supernatant liquid, boiled the precipitate with two or more 
portions of water and washed with hot water till sulphuric acid 
gave no turbidity in the washings. The precipitate washed 
rapidly, and an hour to an hour and a half generally sufficed 
for the jorge ones. In purifying the larger precipitates, they 
were placed in a beaker with from 50 to 100 ce. water and a few 
drops acid. Any lumps were broken up by a rod, and the whole 
was boiled half an hour ormore. The smaller precipitates were 
treated in the crucibles. In all cases the purifying was contin- 
ued till sulphuric acid gave no reaction for barium salts in the 
last filtrate. The precipitates, weighing from 2 to 4gr., lost by 
aigeenng with dilute chlorhydric acid from 0°007 to 0-020 gr. 
0 Professors Johnson and Allen I desire to return thanks 
for their assistance and for many valuable suggestions. 
Sheffield Laboratory, July 1st, 1872. 
* Caldwell’s Agricultural Qualitative and Quantitative Analysis, p. 246. 
+ Zeit. fir Anal. Chem., Bd. ix,s.52. — Zeit. far Anal. Chem., Bd. x, s. 396. 
