S. p. Sadiler— Occurrence of Tartronic Acid. 117 



red fuming nitric acid. After allowing them to rest until all 

 gas evolution has ceased (which usually takes some six days), 

 the solution is evaporated down at a gentle heat until the 

 fumes of nitric acid are no longer perceptible. It is then very 

 thick and syrupy. It is now diluted with water, and plumbic 

 carbonate is added in excess. The oxalate and undissolved 

 carbonate are filtered offj and the solution slightly concentrated 

 and allowed to crystallize. The glycerate of lead deposits in 

 thick crystalline crusts. These are separated from the mother- 

 liquor, dissolved, and the lead precipitated out from the solu- 

 tion by sulphuretted hydrogen. 



The colorless or light straw-colored filtrate is somewhat con- 

 centrated, and calcic carbonate is added to neutralization. The 

 solution is filtered, if necessary, and to the filtrate is added 95 

 per cent alcohol. The calcium salts present are all precipi- 

 tated, in greater part at once, and completely on standing 

 twelve hours. 



If the solution had been very concentrated the calcium salt 

 is precipitated in a granular condition. If, on the other hand, 

 it was more dilute, the salt only separates gradually, and has a 

 beautiful micaceous and scaly appearance. 



I had at first considered this precipitate to be pure calcium 

 glycerate, but found on dissolving it in water, in order to free 

 it from the lime and obtain the glyceric acid, that while the 

 greater portion dissolved readily in warm water, a considerable 

 portion, although not more than one-tenth of the whole amount, 

 remained and dissolved only on continued boiling. This, 

 when filtered off and washed in cold water, appeared as a dull 

 white, almost impalpable powder, contrasting in appearance 

 with the crystalline glycerate. 



It was dried carefully at 100° until constant weight was 

 obtained. 



Calcium determinations were first made. Weighed portions 

 'ted in a platinum crucible once or twice with excess 

 ntrated sulphuric acid until the weight remained 



salt yielded -4925 grms. CaSO« equal to 25-22 



salt yielded 1505 grms. CaSO, equal to 2516 



The theoretical per cent of calcium in calcium tartronate is 

 25'32, while in calcium glycerate, allowing for two molecules 

 of water of crystallization, it is 13-99. 



I had analyzed the micaceous preparation of calcium gly- 

 cerate about the same time, and had gotten in two determina- 

 tions, 14-03, 14-07 per cent of calcium respectively. The dif- 

 ference was so great that I could not understand it. On 



