584 CONSIDERATION OF CARBON COMPOUNDS. 



all of which are official. They are white salts, readily soluble in 

 water. In the presence of free alkali, the solutions absorb oxygen 

 from the air and become colored. Solutions of salicylates are incom- 

 patible with acids, salicylic acid being precipitated. 



Bismuth subsalicylate is official and has approximately the com- 

 position, C 6 H 4 (OH)CO 2 BiO. It is a white, amorphous or crystalline, 

 odorless and tasteless powder, permanent in the air, and almost insol- 

 uble in water. Alcohol or ether extracts salicylic acid, with decom- 

 position of the salt. 



Strontium salicylate, (C 6 H 4 (OH)CO 2 ) 2 Sr + 2H 2 O, which is official, 

 is a white crystalline powder, odorless, and having a sweetish saline 

 taste. It is soluble in 18 parts of water and 66 parts of alcohol. It 

 is incompatible with ferric salts, mineral acids, quinine salts in solu- 

 tion, spirit of nitrous ether, sulphates and carbonates, and sodium 

 phosphate in powder. 



Mercuric salicylate, C&H^QQ /Hg, is prepared by heating on a water- 

 bath 21.5 parts of yellow mercuric oxide, 15 parts of salicylic acid, and a little 

 water until the mixture is perfectly white. It occurs as a white, amorphous 

 powder, tasteless, and neutral to litmus paper, slightly soluble in water or alco- 

 hol, but soluble in solutions of sodium hydroxide and sodium carbonate, form- 

 ing a double salt. It is soluble also in warm solutions of chlorides, bromides, 

 and iodides. It is used as a disinfectant, and as a remedy in syphilis and in 

 certain skin diseases. 



Analytical reactions. 



1. Add to solution of salicylic acid or its salts ferric chloride: a 

 reddish-violet color is produced, yet noticeable in solutions containing 

 1 part of salicylic acid in 500,000 parts of water. 



2. Add some cupric sulphate : a bright green color will result. 



3. Dissolve some salicylic acid or sodium salicylate in methyl alco- 

 hol and add one-fourth the volume of sulphuric acid. Heat gently 

 and set aside for a few minutes. On reheating, the odor of methyl 

 salicylate is developed. 



Aspirin, C6H 4 .0(CH 3 CO)COOH (Acetyl-salicylic acid ), is obtained by the 

 prolonged action of acetic anhydride on salicylic acid at about 150 C. It forms 

 colorless needles, melting at 135 C., odorless, and of an acidulous taste, solu- 

 ble in 100 parts of water and freely in alcohol or ether. Boiling water or 

 alkalies decompose it, liberating acetic acid. 



Salicin, C 13 H 18 7 . This glucoside is found in several species of Salix (wil- 



