and its Derivatives. 247 



Two silver salts wore formed — the acid salt by precipitating 

 the acid in presence of nitric acid with an insufficient quantity 

 of silver nitrate, and the neutral salt by adding excess of 

 silver nitrate to the acid or its potassium salt. They are both 

 white gelatinous precipitates when precipitated from cold 

 solutions ; but from boiling solutions they come down in a 

 curdy state. In the latter form they are easily filtered through 

 cloth. They are enormously bulky, and almost, although not 

 quite, insoluble in water. They are not quickly discoloured 

 by light. 



Neutral salt C^HsNJ^gglf. 



I. 0-3057 grm. gave 0'1720 grm. Ag, — 56*26 percent. 



II. 0*5209 grm. gave 0*2943 grm. Ag, = 56*49 per cent. 

 Theory requires 56*69 per cent. 



Acid salt.—C, Hs k| coOAg ' 



I. 0*3355 grm. gave 0*1313 grm. Ag, = 39*1 per cent. 



II. 0*2005 grm. gave 0*0777 grm. Ag, = 38*75 per cent. 



Theory requires 39*41 per cent. 



When heated, these salts behave like mercury sulphocyanide, 

 leaving a very light porous mass of metallic silver. 



All the salts of dicarbopyridenic acid, when heated, give off 

 a basic smeU resembling that of pjTidine, while a small car- 

 bonaceous, residue is left. 



Dicarhojyi/ridenic Cliloride. — Five grms. of acid were mixed 

 in a small retort ^vith 13*5 grms. of phosphoric chloride. The 

 reaction soon commenced, hydrochloric acid and phosphoryl 

 chloride being abundantly evolved for about an hour. The 

 mixture was then heated, and all the volatile contents of the 

 retort distilled over; a small quantity of charcoal was left. 

 The last portions of the distillate solidified. The whole of the 

 distillate was redistilled : phosphoryl chloride came over below 

 110°; and after it had ceased to distil over, the mercury rose 

 very rapidly to 284°, at which temperature the chloride dis- 

 tilled. It was washed with cold water once or twice, and 

 dried, first between folds of blotting-paper, and then over 

 sulphuric acid. 



The chloride is insoluble in water, soluble in alcohol, with 

 decomposition, and very sparingly soluble in ether. When 

 melted, and allowed to cool, it solidifies in long needles, v/hich 

 shoot out from the sides of the vessel into the still liquid 

 portion. Its melting point is 60-5-61°. It is a compara- 



