713 



the filtrate from the oxalate of lime over sulphuric acid in vacua, 

 The glyoxylate of ammonia is obtained in small, prismatic and colour- 

 less crystals, which dissolve easily in water. The concentrated solu- 

 tion turns yellow when it is boiled, or evaporated at 100 C. It pro- 

 duces with nitrate of silver and acetate of lead crystalline precipitates 

 at once, but with sulphate of copper only after the lapse of some 

 time. . Solution of caustic potash, mixed with it, causes the evolution 

 of ammonia even at common temperatures. 



According to the composition of glyoxylate of ammonia, the for- 

 mula of glyoxylic acid is C 2 H 2 O 3 *. It is worthy of notice, that the 

 other salts of this acid which have been examined, contain one or two 

 atoms of water which cannot be expelled without decomposing the 

 compound. 



Glyoxal is oxidized, by treatment with dilute nitric acid, into oxalic 

 acid, and as an intermediate substance glyoxylic acid is formed. 



C 2 H 2 2 = Glyoxal. 



C 2 H 2 O 3 = Glyoxylic acid. 



C 2 H 2 O 4 = Oxalic acid. 



Glyoxal has not been proved with certainty to be one of the pro- 

 ducts of the oxidation of glycol ; nevertheless its formation from this 

 alcohol may be foreseen with great probability, as it stands to gly- 

 oxylic and oxalic acids, both of which are formed by the oxidation of 

 glycol, as ethylic aldehyde does to acetic acid. The relation of gly- 

 oxylic to oxalic acid is like that of sulphurous to sulphuric acid. 



Glyoxylic acid. Sulphurous acid. 



SH 2 4 



Oxalic acid. Sulphuric acid. 



Glyoxylic acid resembles in many respects formic acid/ Concen- 

 trated sulphuric acid separates from the salts of formic acid carbonic 

 oxide, whilst it combines with the rest of the constituents. Glyoxy- 

 late of lime dissolves in an excess of sulphuric acid, and the solution 

 evolves at a temperature of from 40 to 50 C., without blackening, 

 pure carbonic oxide. At the end of the experiment, and when the 



* " On Glyoxal," Phil. Mag. Jan. 1857 ; Ann. der Chem. und Pharm. cii. 29. 



