Nitrogen in Organic Compounds. 267 
Art. V.—On the Method of Drs. Varrentrapp and Will for 
estimating the Nitrogen in Organic Compounds ; by J. Law- 
RENCE Suiru, M. D. 
TO THE EDITORS. 
As I sent you some time since, an account of a new method 
invented by MM. Varrentrapp and Will for estimating the quan- 
tity of nitrogen contained in organic substances,* it becomes my 
duty to see that you are furnished with an account of M. Reizet’s 
investigation of this method, which investigations were presented 
to the Académie des Sciences in July of last year. 
M. Reizet finds that the method is applicable, with some care, 
to substances containing large quantities of nitrogen, and small 
quantities of carbon, but when we analyze a substance poor in 
nitrogen and rich in carbon, the result is invariably inaccurate. 
M. Reizet was led to suspect that there were errors attendant 
upon this method, from the fact that some years ago Mr. Faraday 
showed that organic substances containing no nitrogen, when 
heated with potash in contact with air afforded ammonia, a cir- 
cumstance which must affect materially MM. Varrentrapp and 
Will’s method, for they burn the organic substance, mized with 
potash and lime, in a tube, the tube being partly filled with air, 
so that when heated not only would all the nitrogen of the sub- 
stance be converted into ammonia, but also the nitrogen of the 
air contained in the tube, so that when the nitrogen was calcu- 
lated from this ammonia, a larger quantity than the substance 
rarely contained would be indicated. 
Sugar and other substances devoid of nitrogen were burnt by 
M. Reizet, after the method made mention of, and he stated to 
me that he has obtained as much as 2 per cent. of nitrogen in 
burning 15 grains of sugar with the mixture of potash and lime, 
and the truth of which I have since witnessed. ‘The following 
is a table of the results of some of his experiments upon sugar. 
0.250 gram. sueat furnished 0.0038 gram. nitrogen. 
Wia00). = i 0.0075“ i 
1.000 “ dy ° 0.0127 “* 
1.500. “ ay : Uso °° ee 
2.000 6e a a4 0.0153 66 ce 
* See this Journal, Vol. xu, p. 253, April, 1842. 
