592 CONSIDERATION OF CARBON COMPOUNDS. 



3. The addition of ferric chloride to solution of antipyrine causes 

 a deep-red color, changing to yellow on the addition of sulphuric 

 acid. 



4. Mercuric chloride, as well as tannic acid, produces a white pre- 

 cipitate. 



Incompatibilities. In addition to those indicated in the above tests, the 

 following may be mentioned : A mixture of antipyrine and calomel produces 

 a poisonous organic mercury compound ; with phenol, even in dilute aqueous 

 solution, an oily mass is formed; rubbed with sodium salicylate, a pasty mass 

 is produced, in solution, however, there seems to be no eftect ; with beta-naph- 

 thol, a moist mixture results ; rubbed with chloral hydrate, an oil is produced. 

 On the other hand, antipyrine increases the solubility in water of caffeine and 

 the quinine salts. 



Salipyrin is antipyrine salicylate, obtained by direct combination of anti- 

 pyrine and salicylic acid. It is a white odorless powder, with a harsh, sweetish 

 taste, and is almost insoluble in water. 



Resopyrin is a compound of antipyrine and resorcin. Hypnal is a com- 

 pound of antipyrine and chloral hydrate. Pyramidon is a dimethyl-amido 

 substitution product of antipyrine. Ferripyrine is a combination of anti- 

 pyrine and ferric chloride. Many other combinations are known. 



Antipyrine is a constituent of many " migraine powders." 



Pyridine, C 5 H 5 N. This substance has been mentioned above as 

 being a constituent of bone-oil. Other substances have been isolated 

 from this oil and have been found to form a homologous series : 



Pyridine, C 5 H 5 N Lutidine, C 7 H 9 N 



Picoline, C 6 H 7 N Colliding C 8 H U N 



Pyridine is of special interest, because it has been found that sev- 

 eral of the alkaloids, such as quinine, cinchonine, etc., when oxidized, 

 yield acids containing nitrogen, which bear to pyridine the same 

 relation that benzoic acid bears to benzene, or that acetic acid bears 

 to methane. 



Thus, when nicotine is treated with oxidizing agents, nicotinic 

 acid, C 6 H 5 NO 2 , is obtained, which, when distilled with lime, breaks 

 up into pyridine and carbon dioxide, thus : 



C 6 H 5 N0 2 = C 5 H 5 N + C0 2 . 



The relation of nicotinic acid to pyridine, of benzoic acid to ben- 

 zene, acetic acid to methane, may be shown thus : 



