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



heat-units evolved by the union of the carbon, hydrogen, and 

 nitrogen, plus that evolved by the formation of their salts, is 

 probably greater than that evolved by their oxidation. 



I . [t is consequently only in alkaline solution that they can 

 be oxidized. In this case, the amount of heat evolved by the 

 acid formed by oxidation uniting with the alkali increases the 

 sum of thermal units evolved by their oxidation to a number 

 larger than that evolved during the formation of the base. 

 The amount of heat evolved, moreover, is not increased by 

 that arising from a union of the base with an acid. 



5. At least three isomerides are formed by replacement of 

 two atoms of hydrogen in pyridine by carboxyl, COOH. From 

 analogy with benzol, and consideration of the greater com- 

 plexity of the molecule of pyridine, it is highly probable that 

 more than three exist. These acids are produced by oxidizing 

 picoline and its higher homologues, and probably also by 

 oxidizing pyridine. This behaviour is analogous to that of 

 benzol ; for benzol yields acids containing more than six atoms 

 of carbon when oxidized. From picoline, C G H 7 1ST, it was to 

 be expected that monocarbopyridenic acid, C 5 H 4 N.COOH, 

 should be produced ; this acid has been obtained only by the 

 oxidation of nicotine ; a-dicarbopyridenic acid is the only one 

 produced in large quantity by the oxidation of picoline. 

 When lutidine, C 7 H 9 N ; is oxidized, a mixture of at least three 

 isomeric acids of the formula C 5 H 3 N (CO . OH) 2 is formed. 

 This would imply the existence of as many different isomeric 

 lutidines : and indeed it is highly probable that such iso- 

 merides exist ; for great difficulty is experienced in separating 

 isomeric liquids, especially (as in this case) when the presump- 

 tion is that their boiling-points are almost identical. 



6. These isomerides may be represented in graphic formulae 

 as on page 27. A closed chain appears best suited to express 

 the behaviour of the bases and the isomeric compounds de- 

 rived from them. I failed in several attempts to convert the 

 dicarbopyridenic acid into its alcohol (from which I had hoped 

 to obtain a base), owing to the instability of the acid at a high 

 temperature and the small yield of aldehyde when the acid 

 was distilled with calcium formate. I had hoped to achieve 

 the formation of the base by the following stages : — 



C 5 H 3 N (CO . OH) ; 0, H 3 N (CHO) 2 ; C 5 H 3 N (CH 2 OH) 2 ; 

 C 5 H 3 N . (CH 2 Cl) 2 ; and C 5 H 3 N (OH,),. 



From similar reasons, an attempt to prepare lutidine, 

 C 7 H 9 N, by distilling the methyl ether of the a-acid proved 

 abortive ; in every case, pyridine was formed. In spite of 

 these failures, it appears to me probable that picoline is methyl- 

 pyridine, lutidine dimethyl-pyridine, etc., — the presence of 



