Dr. Debus on the Action of Nitric Acid on Glycerine. 203 



Concentrating the filtrate from the oxalate of lime by evaporation 

 in the water-bath. A little ammonia escapes with the steam, 

 and therefore it is necessary to add a few drops of this reagent 

 to the liquid ia order to render it neutral again. It is then 

 placed along with some sulphuric acid under a bell-glass and 

 left to crystallize. In this way beautiful prismatic crystals of 

 the desired substance are obtained. 



0"355 grm., dried in vacuo and burnt with chromate of lead, 

 gave 0'388 grm. carbonic acid and 0'21-8 grm. water. 



For 100 parts :— 



The salt attracts moisture very quickly, and easily loses am- 

 monia. From these facts, the difference between the numbers 

 obtained by calculation and experiment may be explained. A 

 concentrated solution of gly cerate of ammonia gives off am- 

 monia on boiling ; gradually the liquid assumes a yellow colour, 

 and the smell of ammonia disappears. The dry compound melts 

 on application of heat, and comports itself like the concentrated 

 solution. The latter does not change the colour of litmus-papei", 

 and when diluted with a little water, produces no precipitates 

 with the nitrates of lead and of silver, nor with the chlorides of 

 iron and of calcium. 



Ghjcerate of Zinc, (C^ H^ ZnO'')^ + WO. 



Into a warm solution of glyceric acid, carbonate of zinc was 

 introduced till the acid reaction had nearly disappeared and the 

 filtered liquid was concentrated by evaporation. After allowing 

 it to stand for some time, small colourless crystals of the above 

 compound ucre obtained. It is easily soluble in cold and warm 

 water : sulphuretted hydrogen removes the zinc from the solu- 

 tion completely. 



0-290 grm., dried in vacuo and burnt with chromate of lead, 

 gave 0-265 grm. carbonic acid and 0-113 grm. water. 



In 100 parts :— 



Carbon . . . . 2492 

 Hydrogen. . . . 4-32 



Calculated according to the formula 2(C3 11^ ZnC) + H^O :— 



Carbon .... 24-55 

 Hydrogen . . . 4-09 



