948 ORGANIC ACIDS. 



taric acid are replaced by a metallic oxide, an acid or neutral 

 tartrate is formed, and when the 2 atoms of metallic oxide are 

 different, a double tartrate. 



Neutral tartrate of potash, 2 KO,C 8 H 4 O 10 is anhydrous, and 

 soluble in an equal weight of cold water. Acid tartrate of potash 

 (bitartrate), HO.KO,C 8 H 4 O 10 is also anhydrous, soluble in 18 

 parts of boiling water, and in 1 84 parts of water at 68 ; it is 

 insoluble in alcohol. Purified tartar, when heated alone, gives 

 a carbonaceous mixture (black flux), and when deflagrated with 

 2 parts of nitre, it leaves white carbonate of potash (white flux}. 

 Tuartrate of potash and soda, or rochelle salt, KO.NaO,C 8 H 4 O 10 

 -flOHO (Schulze), is formed by neutralising acid tartrate of 

 potash with carbonate of soda, is soluble in half its weight of 

 cold water and persistent in air. It crystallizes with two equiva- 

 lents of the tartrate of potash and boracic acid, and forms a 

 double salt, which is anhydrous. Neutral tartrate of ammonia, 

 2NH 4 O,C 8 H 4 O 10 + 2HO (Dulk). Acid tartrate of ammonia 

 resembles acid tartrate of potash. A hot solution of this salt 

 dissolves a large quantity of arsenious acid, and yields, by 

 evaporation, large and transparent crystals of a salt of two bases, 

 NH 4 O.AsO 3 ,C 8 H 4 O 10 , analogous in composition to tartrate of 

 potash and antimony. Tartrate of potash and boracic acid, 

 KO.BO 3 ,C 8 H 4 O 10 (Duflos), is a white uncrystalline mass, very 

 soluble in water, obtained by dissolving a mixture of 47 i parts 

 of cream of tartar (I atom), and 15^ parts of crystallized boracic 

 acid (1 atom), by means of hot water. Heated in a dry condi- 

 tion to 482 (250 centig.), this salt loses 2 HO, like tartrate of 

 antimony and potash, at the expense of the elements of the 

 acid, the empyrical formula of the salt becoming C 8 H 2 O 8 .KO,BO 3 

 (Soubeiran and Capitaine). Tartrate of potash and peroxide of 

 iron is a pharmaceutical preparation ; its composition when 

 dried at 212 is KO.Fe 2 O 3 ,C 8 H 4 O 10 , (S. and C.). Tuartrate of 

 antimony is a salt, crystallizing with difficulty, of which the 

 composition is unknown. Three double tartrates of antimony 

 and potash are known : (1) Tartar emetic (page 639,) the 

 formula of which, dried at 212, is KO.SbO 3 ,C 8 H 4 O 10 , and heated 

 to 392 (200 centig.), KO.SbO 3 C 8 H 2 O 8 . (2.) Tartar emetic 

 combines with 3 atoms of the acid tartrate of potash, and forms 

 a crystallizable double salt, when the mixture of these two salts 

 is kept constantly boiling in the preparation of tartar emetic 



