I. 



II. 



C 7 H 3 NAg 2 4 . 



21-73 



22-58 



22-04 



0-70 



1-22 



0-78 



56-60 



56-78 



56-69 



MR JAMES DEWAE ON THE OXIDATION PRODUCTS OP PICOLINE. 193 



Calculated centessimally these results give — 



Carbon, ........ 



Hydrogen, ........ 



Silver, ......... 



In order to determine the equivalent of the acid, I took 0*5392 grm. of acid 

 dried at 100° C. and titrated with pure caustic soda solution, every 1-813 c.c. 

 containing 23 mgrm. of sodium ; 1 1 *7 c. c. of soda neutralised the acid taken. The 

 point of saturation was well marked. The equivalent of the acid, from this de- 

 termination, was, therefore, 83*55; as determined by analysis of the silver salt it 

 was 83*5. The atomic weight of the acid taken as C^H.NO^ was exactly double the 

 equivalent found, which, if true, would necessarily involve the acid being bibasic. 

 In order to determine the basicity of the acid, the ammonium salts were the 

 only combinations that I specially examined. 0*4739 grm. of the acid carefully 

 treated with excess of ammonia, and dried at 100° C, increased in weight by 

 0*0481 grm., gain = 10*13 per cent. ; gain on the acid ammonium salt of fore- 

 going formula = 10*17 per cent. The neutral ammonium salt was extremely 

 soluble in water, whereas the acid salt was much less soluble, and could readily 

 be obtained in the form of fine silky needles when the solution was evaporated. 

 From the above data there can be little doubt that the acid was bibasic, bearing 

 the same relation to pyridine that phthalic acid does to benzol. The acid melted 

 at a temperature of about 210° C, frothed, evolved a small quantity of carbonic 

 anhydride, and emitted the readily recognisable smell of these bases. It was 

 easily decomposed when heated with soda-lime, evolving a basic substance, no 

 doubt pyridine. The mercury, copper, cadmium, and zinc salts were all readily 

 soluble in water. The barium and calcium salts were also soluble, and were 

 obtained by adding the respective chlorides to the neutral sodium or ammonium 

 salt ; they crystallised in minute prismatic needles. The silver salt of this acid 

 was specially characteristic. On the addition of nitrate of silver to a solution of 

 the acid or its neutral ammonium salt, a white gelatinous precipitate immediately 

 separated out — it was insoluble in boiling water, and was not visibly affected by 

 exposure to light. The insolubility of this salt would enable us more readily to 

 separate the acid from the other products of the oxidation reaction than the 

 process first quoted in this paper. 



Along with the acid just described, as separated by the process detailed, 

 there was found associated with it another acid substance having a very much 

 higher atomic weight. The crystalline mass, obtained by the addition of sul- 

 phuric acid to the alkaline liquid from the oxidation operation, purified by solu- 

 tion in and recrystallisation from alcohol, and dried over sulphuric acid by means 

 of an air-pump, had an equivalent weight of 121. The crystals were hydrated, 

 and lost 4*9 per cent, of their weight when dried at 100° C. The sodium 



VOL. XXVI. PART I. 3 E 



