brown mustard, and E is commercial ground seed. These samples 

 were furnished by the Microchemical Laboratory. Sulphur was also 

 determined on five samples of vulcanized rubber furnished by the 

 Contracts Laboratory. 



The 60 determinations were made without repeating any, except 

 No. 8136, unless a loss occurred by the leaking of the crucible. This 

 happened in three instances only, so that the work represents fairly 

 well the results which the two methods will give under the same con- 

 ditions without repetition and selection of results. Twelve determina- 

 tions were made at a time with each kind of material, two determinations 

 on each sample, and two blanks. The results obtained are given in 

 Table 1. The peroxid fusions were not hurried, but were allowed to 

 fuse for three or four hours. No. 8136 is a sample of rubber tubing 

 which was not ground very finety, and which had been found to con- 

 tain about 50 per cent of free sulphur. These facts probably account 

 for the discrepancies in the determination. 



[Cir. 56] 



