OXALIC ACID. 155 



with methyl or ethyl iodide, and subsequent addition 

 of water. The acid methyl ether, methyloxalic acid 

 C 2 4 .H.CH 3 , is contained in the mother-liquor from the 

 neutral ether. "When in a free state, it decomposes 

 easily. 



Ethyl oxalate (Oxalic ether), C 2 4 (C 2 H 5 ) 2 , is formed 

 like methyl oxalate ; is prepared most readily in the 

 following manner : A mixture of 3 parts oxalic acid, 

 dehydrated at 100, and 2 parts absolute alcohol, in a 

 tubulated retort, is heated slowly in an oil-bath until 

 the thermometer shows 125-130 ; in the mean time the 

 vapor of 2 parts absolute alcohol is conducted upon the 

 bottom of the retort in an uninterrupted current. The 

 product is then distilled, and that portion which boils 

 at 182-186 collected separately. Colorless liquid with 

 a slight odor ; specific gravity, 1.0824 ; boiling point, 

 186 ; does not mix with water. Conducts itself 

 towards water and ammonia, and zinc and the alco- 

 holic iodides, like the methyl ether. Its solution in 

 absolute alcohol gives a crystalline precipitate with an 

 alcoholic solution of potassa. This is the potassium 

 salt of ethyloxalic acid C 2 4 .H.C 2 H 5 , which, in a free 

 state, is readily decomposed. 



Ethyloxy-oxalylchloride, C 4 H 5 3 C1= C 2 2 <gj 2H5 



Is formed by the action of phosphorus oxichloride on 

 potassium ethyloxalate. Colorless, clear, mobile liquid, 

 of a suffocating odor ; boils at 140 ; specific gravity 

 at 16, 1.216 ; fumes in contact with air, and is con- 

 verted into oxalic acid. 



COKH 2 

 Oxamide, C 2 H 4 ^" 2 2 = - 2 is formed by the 



decomposition of oxalic ether with ammonia ; by con- 

 ducting cyanogen into strong hydrochloric acid ; further 

 from cyanogen and water in the presence of a very 

 small quantity of aldehyde; and, in small quantity, 

 by mixing hydrocyanic acid with manganese super- 

 oxide and a little sulphuric acid. White powder or 



