20 Dr. W, Ramsay on Picoline and its Derivatives. 



dissolved in water, neutralized, and precipitated while hot with 

 lead nitrate, less being used than was necessary to combine 

 with all the acid present. The precipitate was white and 

 flocculent. When decomposed with sulphuretted hydrogen 

 it yielded a liquid from which, on concentration, dicarbo- 

 pyridenic acid separated out in its usual form of hair-like 

 needles, and when purified by crystallization from water was 

 obtained in its two other crystalline forms, viz. naphthalene- 

 like plates and short thick crystals. Its purest form, the 

 thick crystals were converted into the silver salt, after deter- 

 mination of the water of crystallization. It contained 10*94 

 per cent, of water ; and the silver salt, on ignition, was found 

 to contain 56*57 per cent, of silver. Dicarbopyridenic acid, 

 in the same crystalline form, crystallizes with 9*83 per cent., 

 or one molecule of water; and its silver salt contains 56*69 

 per cent, of silver. The silver salt was almost completely 

 insoluble in boiling water, and was gelatinous and very bulky. 

 The filtrate from a boiling solution deposited a few amorphous 

 flocks on cooling. 



The calcium salt, prepared by addition of calcium chloride 

 to a hot solution of the ammonium salt, crystallized in thin 

 plates, usually grouped together in masses. It contained 

 17*47 per cent, of water, which it lost at 150°, and the an- 

 hydrous salt 19*96 per cent, of calcium. C 7 H 3 N0 4 Ca. 

 2^ H 2 O requires 18*00 per cent, of water, and the anhydrous 

 salt 19*51 per cent, of calcium. I had not obtained the salt 

 crystallized with water before ; that described in my last 

 memoir was anhydrous. On evaporation of the solution of 

 the calcium salt, needles were precipitated which were an- 

 hydrous and on analysis yielded 19*01 per cent, of calcium. 

 The formula of this acid is certainly C 7 H 5 N0 4 ; and from its 

 crystalline forms it appears to be identical with the dicarbo- 

 pyridenic acid discovered by Professor Dewar. The yield 

 was somewhat more than ten grams. TVhether it is derived 

 from lutidine by oxidation, or from a possible impurity of 

 picoline in the lutidine, I am unable to decide. 



The mother liquor of the dicarbopyridenic acid contained 

 a mixture from which an acid crystallizing in groups of aci- 

 cular crystals radiating from a common centre was deposited, 

 but not in sufficient quantity for complete examination. From 

 consideration of its crystalline form it is probably identical 

 with one shortly to be described. 



The remainder of the solution of potassium salts, from which 

 the dicarbopyridenic acid was precipitated in combination 

 with lead, was treated with excess of lead nitrate. A copious 

 flocky precipitate came down, from which the acids were 



