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V. — A Contribution to the Chemistry of Nitroglycerine. By Matthew 

 Hay, M.D., Assistant to the Professor of Materia Medica in the 

 University of Edinburgh. 



(Communicated by Professor Crum Brown.) 



Introductory. — In the course of an inquiry into the physiological and 

 therapeutical action of alkaline nitrites, and allied substances, I was struck 

 with the strong resemblance which the action of nitroglycerine bears to that 

 of the nitrites.* The resemblance is, indeed, so well marked, that the action of 

 the one may be held to be identical with that of the other, unless in respect of 

 intensity. The suggestion, therefore, naturally occurred to me, that nitro- 

 glycerine is not a nitrate of glyceryl, as it is always represented, but a nitrite. 

 For no ordinary nitrate, as an alkaline nitrate or nitrate of ethyl, nor any 

 compound of glyceryl with another acid, as sulphuric acid, produces an action 

 on the body at all resembling that of nitroglycerine. On referring to the 

 various investigations which had been made for the purpose of ascertaining the 

 chemical constitution of nitroglycerine, I found that none of them was 

 sufficiently extended and exact to place beyond doubt its precise nature. The 

 danger in manipulating so explosive a body had evidently prevented the 

 various chemists from making a thorough examination of its composition. I 

 at first thought that nitroglycerine might be a nitrite of glyceryl, having its 

 nitrous acid so intimately combined with the glyceryl, that the acid did not 

 exhibit its reactions when tested for in the usual way ; just as the acids of other 

 ethereal compounds will not yield their usual reactions, unless special means 

 are taken to forcibly dissociate the acid from the base ; for example, the acid 

 of acetate of ethyl, or of chloride of ethyl. Certainly nitroglycerine gives no 

 blue colour with a solution of starch and iodide of potassium and sulphuric 

 acid, a. very delicate test for the presence of nitrous acid. In order, however, 

 to apply the test to the separated acid of nitroglycerine, I mixed an alcoholic 

 solution of nitroglycerine with an alcoholic solution of pure caustic potash. The 

 potash was ascertained to be free from nitrite, which I have frequently found 

 present in small quantity in various specimens of ordinary potash. Decomposi- 

 tion of the nitroglycerine quickly occurred, and the fluid, when now tested for 

 nitrous acid, was found to contain the acid in abundance, and so much of it, 

 that for the moment I believed that nitroglycerine was, in reality, a nitrite of 



* Matthew Hay, Practitioner, March and June 1883. 

 VOL. XXXII. PART I. M 



