DR MATTHEW HAY ON THE 



The degree of alkalinity of (IV.) was ascertained by titration with a stand- 

 ard solution of sulphuric acid (30 in 1000). 62 c.c. of standard acid were 

 required for complete neutralisation, which is equivalent to 0203 grms. of 

 potassium hydrate, which, subtracted from 1-50 grms., the quantity of potash 

 originally added, gives 1-297 grms. as the amount of potash actually used up, 

 or a little more than the theoretical quantity. It is noteworthy in these 

 experiments that where less than five molecules of potash, although more than 

 three, were added to one of nitroglycerine, a quantity of nitroglycerine could 

 be observed to remain unclecomposed, as it was precipitated on the addition of 

 water to the alcoholic mixture, proving that when potash acts on nitroglycerine 

 in presence of excess of the latter, according to the equation I have adopted, 

 the potash is used up in thoroughly decomposing each molecule of the nitro- 

 glycerine, and does not partially decompose a greater number of molecules. 

 The respective yields of nitrous acid are alone sufficient to prove this. 



The amount of potash required for the decomposition of nitroglycerine is 

 interesting in connection with a method described by Beckerhinn # a few years 

 ago for the estimation of the degree of acidification of the ether, whether tri-, 

 di-, or mono-nitrate, in which, after adding what he considered to be excess of 

 caustic potash, he titrated the excess with normal oxalic acid. But his calcula- 

 tions were based on the accuracy of Eailton's equation. It is very difficult, 

 therefore, to understand how he could possibly have obtained satisfactory results, 

 although he claimed to have done so, and quoted two analyses. In the follow- 

 ing year Hess and Schwab t denied the correctness of his method, and made 

 analyses according to it, but obtained widely different results, yet still acknow- 

 ledging Eailton's formula, and ascribing the faultiness of the method to various 

 minor circumstances. 



Action of Ammonia. — The volatile alkali seems to act on nitroglycerine in 

 the same manner as the fixed alkalies, but not so energetically. When excess 

 of strong ammonia was added to an alcoholic solution of nitroglycerine, there 

 was no immediate decomposition of the nitroglycerine, as is the case when 

 potash or soda is added. The resultant mixture remained colourless and 

 showed no precipitate. It was then placed over the water-bath and heated all 

 but to ebullition for one hour ; and in order to preserve excess of ammonia, more 

 of the reagent was added from time to time. It now gradually assumed a deep 

 reddish-brown colour, almost deeper than that observed in decomposition with 

 potash. The maximum intensity of colour was reached after half an hour's 

 heating, so that ammonia acts much more slowly than potash. The amount of 

 nitrons anhydride obtained was equivalent to 345 per cent, of the nitroglycerine 



• Bbokebhhw, Sttzungsb. d. Wien. Akad., Bd. lxxiii. (1870), Abth. 2, S. 235. 

 f JlEsa u. Schwab, Ibid., Bd. lxxv. (1877), Abth. 1, S. 702. 



