Dr. Debus on the Action of Nitric Acid on Glycerine. 199 



phuric acid. After a few days the mother-liquor was evapo- 

 rated. Tlie dry residue consisted of glycerate of lime ; but the 

 crystals were covered with a very thin coating of the appear- 

 ance of varnish. The quantity of the latter was very small, but 

 it showed that a little of the glyceric acid had suffered a change 

 during its preparation. The dry acid could not be converted 

 into powder. A little capsule of platinum-foil contained the 

 substance, dried for ten hours at 105° C. It was weighed 

 within a closed glass tube, placed in the combustion-tube, and 

 well surrounded Viith chromate of lead. 



I. 0'144< grm. gave 0"210 grni. carbonic acid and 0068 grm. 

 water. 



II. O'l 10 grm. gave 0-162 grm. carbonic acid and 0*053 grm. 

 water. 



In 100 parts :— 



I. II. 



Carbon 39-77 40-16 



Hydrogen 5-24 5-35 



Oxygen 



The formula C^ H'' 0^ agrees best with these numbers : — 



Carbon ... 3 36 40-90 



Hydrogen . . 4 4 4-54 



Oxygen ... 3 48 54-56 



88 100-00 



Pyroracemic acid has the formula C^ H'' 0^. A salt of this 

 acid mixed with sulphate of iron turns red : a salt of glyceric 

 acid does not show this reaction. The compounds of the latter 

 also diflPer in composition and properties so much from those of 

 pyroracemic acid, as to clearly establish them as distinct sub- 

 stances. Although glyceric acid is but little fitted for analy- 

 tical operations, its compounds answer this purpose well. Those 

 which I have examined crystallize well, and may easily be ob- 

 tained in a state of perfect purity. The general formula of the 

 glycerates is C^ H''' MO'', and the corresponding hydrogen com- 

 pound, C''H''0'*. Therefore, if the formula for glyceric acid, 

 as deduced from the analyses described above, be correct, it 

 must lose one atom of water at 105° C, and be able to take it 

 up again on coming in contact with bases. 



Biglyccrate of Potash, C^ H^ KO" + C^ H« 0". 



A certain quantity of glyceric acid was divided into two 

 equal parts ; one was neutralized with carbonate of potash and 

 then added to the other part. On evaporating this liquid, first 

 on the water-bath, and afterwards in vacuo over sulphuric acid, 

 pmall white crystals were formed. These crystals, separate^ 



