710 MODIFICATIONS OF ORGANIC COMPOUNDS. 



vapour over the mixture of hydrate of potash and lime heated 

 to redness, gives nothing but carbonic acid, which remains in 

 combination with the alkali, and light carburetted hydrogen 

 C 2 H 4 . The vapour of aldehyde passed over the same mixture 

 at a lower temperature gives acetate of potash and free hydrogen, 

 losing only one equivalent of hydrogen and acquiring one of 

 oxygen, or the reaction is similar to what occurs with the next 

 substance to be mentioned, to which aldehyde has considerable 

 analogy.* Oil of bitter almonds distilled with dry hydrate of 

 potash, gives hydrogen gas and benzoate of potash. 



According to the temperature, ulmic, acetic and oxalic acids 

 appear in other cases, or carbonic acid only. Thus tartaric acid 

 fused with hydrate of potash gives the acetate and oxalate of 

 potash. Acetate of potash distilled with a mixture of hydrates 

 of potash and lime, gives carbonate of potash and light car- 

 buretted hydrogen gas, which on that account is also named the 

 gas of the acetates. Formic acid, alcohol, and bodies in general 

 consisting of carbon, oxygen and hydrogen, when distilled with 

 anhydrous barytes, give the same gas. When substances con- 

 taining nitrogen are boiled in a solution of caustic potash, 

 or fused with the dry hydrate, ammonia is evolved, and acids 

 containing no nitrogen remain in combination with the potash. 

 Some bodies containing much nitrogen lose only, with dry 

 hydrate of potash, a portion of their nitrogen in the form of 

 ammonia ; and the rest acquiring oxygen, assumes the form of 

 cyanic acid, and is protected by the potash from farther de- 

 composition. 



When the acetate of any metallic oxide capable of retaining 

 carbonic acid at a red heat, such as the acetate of soda, potash, 

 barytes, &c., is distilled, a carbonate remains in the retort, 

 while a combustible liquid, acetone C 3 H 3 O distils over. 

 M. Fremy has shewn that sugar, starch and all those ternary 

 compounds of carbon, hydrogen and oxygen, in which the two 

 last are in the proportion to form water, are decomposed 

 when heated in contact with lime in the same manner as 

 acetic acid. They afford acetone, with water and carbonic acid. 

 Benzoic acid distilled with three times its weight of hydrate 

 of lime forms carbonate of lime, with a volatile liquid C 12 H 6 , 



* Annales dc Chimie et de Physique, tome 73, p. 113. 



