Dr. W. Rainsay on Picoline and its Derivatives. 23 



Ferrous sulphate gives a red coloration exactly resembling 

 that produced by a-dicarbopyridenic acid. 



Salts of fi-Dicarbopyridenic acid. 

 Ammonium salt. — This salt was prepared by evaporating 

 the acid to dryness with aqueous ammonia. It is moderately 

 soluble, and crystallizes from a hoj: solution in needles. 

 Synthesis. Taken, 0*4025 gram of acid. 



Gain, on evaporation with ammonia, 0*0925 gram, 



= 18-68 per cent, NH 3 . Calculated, 16*91 per cent. 

 Calcium salt. — Prepared by adding calcium chloride to a 

 hot solution of the ammonium salt. It forms very thin mi- 

 croscopic needles, sparingly soluble in water. 

 Analysis. Taken, 0*3190 gram. 



Loss at 150°, 0*0483 gram, = 15*14 per cent. H 2 O. 



Ca C0 3 0-1320 gram, = 16*55 per cent. Ca. 



Calculated for C 7 H 3 N0 4 Ca . 2H 2 O = 14*93 per cent. H 2 O. 



16*91 per cent. Ca. 

 Iron salt.—The white flocculent precipitate obtained by 

 adding ferric chloride to the acid was analyzed, after being- 

 dried at 150°. 



Taken, 0*1020 gram. 



Fe 2 3 , 0*0304 gram, = 0*0213 gram Fe, or 20*86 per cent. 

 Calculated for (C 7 H 3 N0 4 ) 3 Fe 2 ... Fe, or 18-45 per cent. 

 The salt is probably basic. On addition of ammonia to the 

 moist salt it is converted into ferric hydrate. 



Lead salt. — A white crystalline precipitate, very sparingly 

 soluble in water, prepared from the ammonium salt with lead 

 nitrate. 



Taken. 0*4165 gram. 



Loss at 150° 0*0367 gram,= 8*81 per cent, H 2 O. 

 Lead sulphate 0*3117 gram, = 51*14 per cent. Pb. 

 Calculated for C 7 H 3 N0 4 Pb . 2H 2 O, 8*82 per cent. H 2 O. 



50*73 per cent. Pb. 

 Silver salt. — The silver salt of /3-dicarbopyridenic acid, 

 when precipitated by adding silver nitrate to a solution of 

 the acid, contains 43*56 per cent, of silver, and is probably a 

 mixture of neutral and acid salt, Ifc was this which led me, 

 in my last paper (Phil. Mag. Oct. 1877), to state that the 

 molecular weight of the acids from lutidine was higher than 

 that of the picoline acids. Two analyses of the silver salt 

 prepared in this manner showed it to contain 43*56 per cent, 

 and 44*05 per cent, of silver. When prepared by adding silver 

 nitrate to the ammonium salt, it has the formula C 7 H 3 N0 4 Ag 2 , 

 as the following analyses prove : — 



