2G8 PROCEEDINGS OF THE AMERICAN ACADEMY. 



excess of silver, nitrate is titrated with ammonium sulphocyanate. 

 The sample taken was not perfectly white, but from its gray color 

 evidently contained some carbon which had also distilled to the wall of 

 the furnace. The residue obtained on treating the white powder with 

 water was of a dark grey color. It was evidently carbon and calcium 

 oxide, for (1) it dissolved slightly in a fresh portion of water and 

 gave a distinct precipitate when ammonia and ammonuim oxalate 

 were added ; (2) on treating some that had been exposed to the 

 air with hydrochloric acid it dissolved partly with effervescence, 

 leaving a black residue behind ; and (3) when the hydrochloric 

 acid solution was neutralized with ammonia and ammonium oxalate 

 was added, a large quantity of precipitate was formed. The analysis 

 of the water solution for calcium cyanamide gave 38.59, 39.52, and 38.84 

 per cent corresponding to 13.51, 13.84, and 13.60 per cent nitrogen. 

 An analysis of a sample of the same material used in the Kjeldahl de- 

 terminations gave only 25.96 per cent calcium cyanamide, correspond- 

 ing to 9.09 per cent nitrogen. Since this did not agree with the 

 determinations by the Kjeldahl method or with the values obtained by 

 the same method for other samples, analyses were made by the Perotti 

 method of two more samples. The perfectly white material used in the 

 Kjeldahl method could not be checked again as it had all been used up. 

 The results of the analyses of the powder obtained in Experiment 16, 

 were 15.96 and 15.35 per cent calcium cyanamide, corresponding to 

 5.59 and 5.38 per cent nitrogen. Analyses of the material obtained in 

 Experiment 17 gave 29.10 and 28.95 per cent calcium cyanamide, cor- 

 responding to 10.19 and 10.13 per cent nitrogen. Experiments 16 and 

 17 were made at about the same temperature and still the amount of 

 calcium cyanamide in the powder distilled to the cold part of the fur- 

 nace was quite different. 



Two determinations of calcium in the white powder used in the 

 Kjeldahl determinations were made by first destroying the organic 

 matter with fuming nitric acid and then decomposing the calciimi 

 nitrate by ignition in a platinum crucible and weighing as the oxide. 

 The fuming nitric acid had to be added very slowly as it attacked the 

 white powder with great violence, sometimes causing it to flame. The 

 results were 39.93 and 39.27 per cent calcium, the average of which is 

 39.60 per cent. From this an^ the fact that the content of nitrogen 

 was 12.1 per cent, the amounts of calcium oxide and of calcium 

 cyanamide in the first sample of white powder analyzed were as follows : 



Calcium cyanamide 34.5 per cent 



Calcium oxide 30.5 " " 



Unaccounted for 35.0 " " 



