400 Drushel and Brandegee — Hydrochloric Acid in the 



on the bath for fifteen minutes after its contents had been re- 

 duced to dryness. The dish containing ammonium chloride and 

 other combustion residues was then placed in a drying oven and 

 heated at 110° for five minutes to remove traces of hydro- 

 chloric acid not removed by heating on the steam bath. 



Several preliminary experiments were made to ascertain if the 

 last traces of hydrochloric acid could be removed in a drying 

 oven without a weighable loss of ammonium chloride. Care- 

 fully dried and weighed ammonium chloride was heated on the 

 steam bath and also in the drying oven at different tempera- 

 tures for varying lengths of time and the loss in weight deter- 

 mined. It was found experimentally that no ammonium chlor- 

 ide is lost during the evaporation process, and that the loss 

 by heating one gram of ammonium chloride in the drying 

 oven at 110° for ten minutes did not exceed two tenths of a 

 milligram. Since the amount of material used for a determina- 

 tion of nitrogen seldom exceeded three tenths of a gram, the 

 loss of ammonium chloride in the drying oven at 110° during 

 a period of five minutes could in no case affect the accuracy of 

 the result. The results obtained with pure ammonium chloride 

 are recorded in Table I. 







Table I. 







NH 4 C1 taken 



Hours on 



Temperature 



Time in 



Loss in weight 



grm. 



bath. 



of oven. 



oven. 



grm. 



1-0000 



1 1/2 









1-0425 



1 1/2 







none 



1-0000 



11/2 



120° 



1/2 hr. 



0-0091 



1-2386 





110° 



1/2 " 



0-0009 



1-2378 





105-108° 



1/2 " 



0-0005 



1-0425 





105-108° 



1/2 " 



0-0008 



1-0422 





110-112° 



10 min. 



0-0002 



1-23*77 





110-112° 



10 " 



0-0002 



The most favorable decomposition time and temperature 

 were studied by making a series of experiments with a sample 

 of cyan-acetic ester known to contain a little less than the theo- 

 retical amount of nitrogen. It was found that at moderately 

 low temperatures the decomposition was incomplete at the end 

 of two hours, but that at 200° decomposition was effected 

 quantitatively within this time. In this series the removal of 

 the excess of hydrochloric acid was attempted by making 

 repeated evaporations on the steam bath without final heating 

 in the oven. The results obtained in the latter experiments of 

 the series indicate that the hydrochloric acid can not be com- 

 pletely removed by evaporation on the steam bath alone. This 

 led to the expedient in subsequent experiments of heating the 



