44 Dr. Debus on the Action of Nitric Acid 



slightly, but on addition of ammonia a strong white precipi- 

 tate falls down. Nitrate of silver and ammonia mixed with the 

 same solution precipitated, on application of heat, a very bright 

 and strong coating of metallic silver on the sides of the test-tube. 



Sulphuretted hydrogen acts upon the glyoxal, and it is very 

 probable that merely an interchange of sulphur and oxygen be- 

 tween both substances takes place. 



Sulphuretted hydrogen does not act on the isomeric glycolic 

 acid. Glycolate of lead was decomposed by sulphuretted hy- 

 drogen, and after filtration the excess of the latter expelled by 

 heat. The remaining acid, on being neutralized with carbonate 

 of lime, gave only crystals of glycolate of lime, which did not 

 contain a trace of sulphur. 



Caustic potash, lime, or baryta, convert the glyoxal into gly- 



C2 H^ 03 + Ca HO = C2 H3 Ca03 + H^O. 



Glyoxal. 



A quantity of crude glyoxal was boiled with carbonate of lime. 

 The latter did not dissolve, and the filtrate again furnished on 

 evaporation all the glyoxal employed, with its peculiar qualities. 



Glycolic acid decomposes with the greatest facility carbonate 

 of lime, producing glycolate of lime. 



Some crude glyoxal, prepared as described in the beginning 

 of this papei-, was mixed with slaked lime and water till a slight 

 alkaline reaction became perceptible. After removing the excess 

 of lime by means of carbonic acid, the filtrate furnished to the 

 last drop only crystals of glycolate of lime. The precipitate of 

 carbonate of lime dissolved almost entirely in carbonic acid water, 

 and was on boiling again completely precipitated ; therefore no 

 oxalate of lime or any other similar substance had been produced. 



A quantity of the compound of glyoxal with bisulphite of 

 baryta was dissolved in boiling water, and caustic baryta added 

 till the liquid became alkaline. It now contained a precipitate 

 of a slight yellow colour, which proved to be only sulphite of 

 baiyta, (Ba'O, SO^). The filtrate from the latter was freed from 

 baryta by means of diluted sulphuric acid. The acid liquid thus 

 obtained gave, after neutralization with carbonate of lime, only 

 crystals of glycolate of lime. The latter was recognized by the 

 characteristic shape of its ciystals and by the amount of water 

 of crystallization. 0*370 grm., dried in vacuo, lost at 100° C. 

 O'OSO grm. water. Consequently 100 parts contain: — 



21-62. 

 The formula 2(0^ H^ CaO^) + SH^O requires 



22*1 of water of crystallization. 

 The decomposition of the glyoxal-bisulphite of baryta by baryta 



