and its DevLvatlves. 245. 



tallization from aqueous alcohol, in which it is more soluble 

 than in water, the acid deposits in prisms, and from ether in 

 hairs. 



The acid has no basic properties ; a portion evaporated to 

 dryness ^Yith hydrochloric acid gained no A^eight, showing 

 that no chloride was formed. Mr. Dewar's formula for dicar- 

 bopyridenic acid was confirmed by analysis of the acid, iv:- well 

 as of a number of its salts. 



0-3872 grm. gave 0-7109 grm.COs, and 0-1119 gnu. ILO. 

 = 51*26 per cent. C, and 3-28 per cent. H. Theory for 

 C7 Ho NO4— carbon 50-30 per cent., hydrogen 3*00 per cent. 



When heated to its melting-point, the acid decomposes into 

 carbonic anhydride and pyridine ; hence its formula is 

 written C5H3N(COOH)2. " 



Salts of Dicarhopyridenic Acid. 



The neutral potassium salt, C5 H3N (C00K)2, was pre- 

 pared by neutralizing the acid with potassium carbonate and 

 evaporating. It is extremely soluble in water. When its 

 solution is evaporated over sulphuric acid, it deposits in 

 needles containing 1\ molecule of water. 



After drying at 100°, 0-4030 grm. lost 0-0416 grm., = 10*32 

 per cent. The loss, corresponding to 2H2 0, should amount 

 to 12*90 per cent.^ and to 1\ molecule of w-ater to 10-00 

 per cent. 



( POOTT 



The acid potassium salt, G^YL^1^< rOOTT^ ^^ prepared by 



adding a molecule of the acid to a molecule of the neutral 

 salt. It is much more sparingly soluble in w^ater, and crys- 

 tallizes in small globular masses consisting of tufts of needles 

 radiating from a common centre. 



The sodium salt forms very soluble white crystals. 



Ammonium Salt. — A solution of the acid in alcohol gives, 

 on addition of ammonia, a precipitate consisting of small 

 plates. These plates, viewed by polarized light under a mi- 

 croscope, exhibit phenomena similar to those wdth selenite. 

 Interference is produced, the result of which is that the plates 

 exhibit different colours, the colour depending on the thick- 

 ness. But each single plate of the ammonium salt exhibits a 

 regular gradation of colour without any break of continuity. 

 Does this mean that the opposite sides of the plate are not 

 parallel to each other? 



Calcium Salts. — The neutral salt, C5 H3 JST (002)2 Oa, is 

 soluble in a large quantity of water. During evaporation of 

 its solution to a small bulk, the gait deposits very small 



