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VI. — The Elementary Composition of Nitroglycerine. By Matthew Hay, M.D., 



and Orme Masson, M.A., B.Sc. 



(Communicated by Professor Crum Browx. ) 



Nitroglycerine is commonly described as the tri-nitric ether of glyceryl, and 

 the formula C 3 H 5 (O.N0 2 ) 3 is accorded to it. This theory of its composition 

 is based (1) upon its mode of formation; (2) upon the statement, made by 

 Railton, Williamson, and others, that it is decomposed by potash into 

 potassium nitrate and glycerine ; (3) upon several estimations of the nitrogen 

 which it contains, and one comparative estimation of its carbon. The second 

 argument cannot be accepted, as it has been shown by one of us that the 

 decomposition does not take place in the way stated ; * and the analytical 

 results which have been obtained by the various investigators are so incomplete 

 and mostly so imperfect, and differ so greatly among themselves, that they 

 cannot be taken as affording any proof of the composition of the substance. It 

 seemed to us, therefore, desirable that some accurate estimations should be 

 obtained, not only of the nitrogen but of the carbon and hydrogen. A brief 

 resume of previous analytical results will show that this is the case. 



Railton, t in 1855, attempted to estimate the relative quantities of carbon 

 and nitrogen by Liebig's method. The ratio of the volume of carbonic acid to 

 that of nitrogen required by the formula is 2:1. Railton obtained results 

 varying from 2156 : 1 to 1*912 : 1 ; so that, although they are on the whole in 

 favour of the formula, they cannot be regarded as satisfactory. He made no 

 attempt to estimate the carbon and hydrogen absolutely, as he found it 

 impossible to dry his nitroglycerine, even in an exhausted receiver, on account 

 of its great tendency to decompose. This proves that the substance was 

 impure, as we have found pure nitroglycerine to be perfectly stable in the air 

 and in vacuo. 



Williamson,! in the following year, gave an account of the composition of 

 nitroglycerine, which agrees so exactly with Railton's in every detail, that 

 there can be no doubt that their experiments were made in conjunction, 

 although published separately and without reference to each other. 



Hess, § in 1874, estimated the nitrogen in commercial nitroglycerine 



* See the preceding paper : " Contribution to the Chemistry of Nitroglycerine," by Matthew Hay. 

 f Eailton, Quart. Jour. Chern. Soc, vol. vii. p. 222. 

 J Williamson, Proc. Roy. Soc, vol. vii. p. 130. 

 § Hess, Zeitschr. f. anal Chem., 1874, S. 257. 



VOL. XXXII. PART I. • P 



