296 On the Alteration which Sulphuric Acid 



In a note printed in the same volume, p. 318, Fourcroy and 

 Vauquelin have endeavoured to refute the theory of M. Dabit 

 on the formation of ether, and thQy have justly remarked that 

 this theory, were it true, is incompletely demonstrated. M. Da- 

 bit had not, in fact, given any proof of the existence of his acid, 

 and his theory might therefore be considered as a ])lay of the 

 imagination. However, two years after he published in the 43d 

 volume of the Annales de Chimie, p. 101, a Sequel to his first 

 Memoir, in which he allows that the objection which Fourcroy 

 and Vauquelin had made was well founded j and he replies to 

 it by a series of experiments which do not leave any doubt as to 

 the formation of a particular acid during the conversion of the 

 alcohol into ether by means of sulphuric acid. It is astonishing 

 that these experiments, really very interesting, should remain so 

 long forgotten, and that they should have fixed for the first time 

 the attention of M. Sertuerner, who speaks of them, besides, as 

 if they had never been known. The justice which is due to M. 

 Dabit, as much as the importance of the subject, induces us to 

 give an extract from his memoir: we shall afterwards make known 

 what MM. Sertuerner and Vogel have added to it, subjoining to 

 this notice some observations of our own. 



''Having saturated (says M. Dabit) with carbonate of lime some 

 residue of ether, diluted with water, I filtered it and set it to eva- 

 porate ; 1 obtained a yellowish salt not crystallized. Having 

 dissolved this salt in a sufficient quantity of water to purify it, 

 and to separate from it the sulphate of lime, I filtered it and set 

 it anew to evaporate. 1 obtained a salt partly crystallized in 

 parallelipipedal crystals, without much taste, and which dissolved 

 in about a hundred parts of cold water ; — hot water dissolves it a 

 little more; — exposed to the air it did not experience any alter- 

 ation. 



" The salt which attached itself to the sides of the vessel dur- 

 ing the progress of the evaporation, when it became dry and had 

 acquired a certain degree of heat, carbonized and became acid. 

 When the solution itself was allowed to settle, it presented si- 

 milar phKuomena, Whence could this carbon and acid, which 

 I recognised to be sulphuric acid, arise ? The spirit of wine 

 which vvas fonnd in llie solution appeared to me to have been 

 alone the cause ; and the following experiment proved that 

 1 had conjectured rightly. Some grains of this crystallized 

 salt, with some drops of rectified spirit of wine, steeped in a 

 little water and set to evaporate, yielded the same results. I 

 conceive that the new acid which constitutes the salt of which I 

 speak decomposes, at this degree of heat, the spirit of wine, by 

 abstracting from it the oxygen to pass into the state of sulphu- 

 ric acid, while the carbon of the portion of the spirit of wine de- 

 composed 



