76 DR MATTHEW HAY ON THE 



what actually occurs. It is almost regarded as a fixed law in the chemical 

 decomposition of compound ethers by alkalies, that the alkali unites with the 

 acid of the ether and liberates the alcohol. This does not appear to be the 

 case with nitroglycerine. For no glycerine is formed, and the acid is in great 

 part reduced. But there is no doubt that the reduction of the greater portion 

 of the acid is to be associated with the disappearance of the glycerine, which is 

 evidently oxidised by the oxygen lost by the acid. Therefore, instead of 

 glycerine, we have oxidation products of it, as acetic acid, oxalic acid, formic 

 acid, &c. When nitroglycerine is being decomposed by potash, nitric acid and 

 glycerine or glyceryl occur in a nascent and very active condition, the one as a 

 powerful oxidising substance, the other as a readily oxidisable substance. As 

 a consequence they act on each other, and two out of the three molecules of 

 the nitric acid part each with an atom of oxygen to the glycerine or glyceryl, 

 and this amount of oxygen is sufficient to completely oxidise and break up the 

 glycerine, mostly, if not entirely, into certain organic acids, which, of course, 

 will combine with a portion of the excess of the alkali used for the decomposi- 

 tion. That is one view ; but there is another view, according to which the 

 caustic potash may be regarded as taking an active part in the decomposition 

 of the nascent glyceryl. When pure glycerine is melted with potash, it is well- 

 known that acetate and formate of potash are produced along with free 

 hydrogen." The action is represented by the equation, — - 



C 3 H 5 (OH) 3 + 2KOH = KO. CHO + KO. C. 2 H 3 + OH 2 + 2H 2 . 



The decomposition effected by potash under these conditions may occur even 

 in dilute solution if the glycerine be in a nascent state, more particularly if 

 there be present at the same instant a highly oxidising body like nascent nitric 

 acid, which is promoting the same form of decomposition, and is ready to grasp 

 the nascent hydrogen. The amount of hydrogen set free is precisely the 

 quantity needed to reduce two -thirds of the nitric acid of the nitroglycerine, 

 and the other decomposition products of the equation given correspond toler- 

 ably closely with those actually ascertained to be formed. But if such a 

 decomposition occurs, it implies that five, not three, molecules of hydrate of 

 potash are required to decompose one molecule of nitroglycerine. In accord- 

 ance with these views the action of caustic potash on nitroglycerine may be 

 represented thus : — 



(1) C 3 H 5 -3(0-N0 2 ) + 3KOH = C 3 H 5 -(OH) 3 + 3(K-0-NO ? ). 



Nitroglycerine. Potash. Glycerine. Potassium 



Nitrate. 



(2) C. j H,-(OH) 3 -f-2KOH=KO-CHO-fKO-C 2 H :j O- r -OH 2 + 2H 



Glycerine. Potash. Potassium Potassium Water. Hydn 



Formate. Acetate. 



* Dumas et Stas, Ann. Chim. Plujs., lxxiii., 148. 



