368 M. Ranieri 07i Vulcanic Formation of Sal-ammoniac. 



etted hydrogen, and the liquid evaporated, the succinic acid is 

 obtained in crystals. The quantity amounts to a half per cent, 

 of the fermented sugar. In wine also Pasteur found succinic 

 acid. 



According to the same chemist*, glycerine also invariably 

 occurs among the products of the alcoholic fermentation of sugar ; 

 and he estimates its amount at 3 per cent, of the fermented sugar. 

 It is further contained in all fermented liquors, and especially in 

 wine. 



Bunsen explained the formation and occurrence of sal- 

 ammoniac in lava, by the theory that, in the passage of lava 

 over surfaces covered with vegetation, the nitrogen of the plants 

 becomes free in the form of carbonate of ammonia, which, with 

 the hydrochloric acid continuously evolved from the heated lava, 

 forms sal-ammoniac. Bunsen had observed, some months after 

 an eruption at Hecla, that only the lower part, which had flowed 

 over grass-land, showed sal-ammoniac fumarolcs, and that higher 

 up, and in proj^ortion as the vegetation disappeared, the forma- 

 tion of sal-ammoniac ceased also. This theory was opposed by 

 von Waltershausen, who considered that the volcanic sal-ammo- 

 niac arose from the atmospheric ammonia. 



Ranierit has communicated some observations on the lava 

 stream of Vesuvius in 1850, whicli confirm Bunsen's view. The 

 course of the lava was partly over the old stream of 1834, partly 

 (and especially where it reached the plain) over cultivated land. 

 In the latter portions, sal-ammoniac was found for a year and a 

 half after the eruption, and in considerable quantities. In the 

 lava which had flowed over the older stream, very little sal- 

 ammoniac was found, and few fumaroles. 



The greater number of fumaroles which occur in the lava 

 which has passed over cultivated land, arises from the gases formed 

 by the action of the lava on organic matter, which force their 

 way through the still soft lava. And the small quantities of 

 fumaroles which occui* near the older lava may arise from the 

 decomposition of accidental animal deposits. 



Ranieri admits that the ammonia of the atmosphere may give 

 rise to formation of sal-ammoniac, but only in a subordinate 

 degree. 



* Comptes Rendus, vol. xlvi. p. 85". 

 t Liebig's Annulen, December 1857. 



