Dr. W. Ramsay on Picoline and its Derivatives. 271 



found that when the latter acid is decomposed into pyridene, 

 nitrogen is evolved, and not carbonic anhydride. 



Dewar suggested that pyridine might possibly be obtained 

 by the mutual action of acetylene and hydrocyanic acid on 

 each other at a high temperature. The equation by which the 

 reaction is expressed is this : — 



2C 2 H 2 + HCJSr=C 5 H 5 K 



A gas-holder of acetylene was prepared by burning air in 

 coal-gas ; and from this acetylene the silver compound was 

 formed, so as to ensure its purity. The silver compound was 

 decomposed with hydrochloric acid, and the acetylene, after 

 being washed, was passed through strong hydrocyanic acid, 

 and then through a bright-red-hot iron tube, the other end of 

 which communicated with a Liebig's condenser. Only about 

 2 cubic centimetres of distillate were obtained. Hydrochloric 

 acid was added, and the liquid was evaporated to dryness on a 

 water-bath ; benzol was apparently evolved, as far as could be 

 judged by the smell. Sodium hydrate was added to the 

 residue, when a few drops of an oily liquid separated smelling 

 strongly of pyridine ; unfortunately too little was obtained to 

 admit of confirmation ; but the extremely characteristic smell 

 of the base leaves no doubt that one of the series was actually 

 formed. I propose to repeat this experiment on a larger scale. 



Salts of Picoline. 



Picoline hydrochloride, described by Anderson, is a white 

 extremely deliquescent crystalline salt, and melts at 160°. It 

 is best prepared by neutralizing picoline with hydrochloric 

 acid, and distillation, after evaporation to dryness. 



Picoline hydrobromide may be obtained in the same manner 

 as the hydrochloride, but is more easily prepared by cautiously 

 adding bromine to picoline and distilling the resulting oil. I 

 shall consider the action of bromine on picoline in a subse- 

 quent part of this memoir. Picoline hydrobromide melts at 

 187° ; and its boiling-point is considerably above that of the 

 chloride, and also above the range of a mercurial thermometer. 

 It is a white crystalline mass, and also deliquesces, but not 

 so readily as the chloride. Both the chloride and bromide 

 may be obtained in feathery crystals by using impure picoline 

 as a solvent. 



Picoline hydriodide cannot be prepared by distilling a mix- 

 ture of the base with hydriodic acid ; for picoline is liberated, 

 and the hydriodic acid decomposes, yielding a compound 

 which will be afterwards described. 



Action of Chlorine on Picoline Hydrochloride. — Picoline 



