440 On the Action of Caustic Potash on Glycerate of Potash. 



after recrystallization, dissolved in water and freed from the 

 lime by the careful addition of oxalic acid. Carbonate of zinc 

 was now added to the filtrate from the oxalate of lime, as long as 

 an ciFervcscence took place, and after some boiling the undis- 

 solved carbonate of zinc removed by filtering. The liquid gave 

 on evaporation crystals resembling lactate of zinc, which served 

 for the following determinations : — 



I. 0-384 grm., dried over sulphuric acid, lost at 100° C. 0-070 

 grm. water. 



The same quantity of substance dissolved in water and preci- 

 pitated with carbonate of potash, gave, according to the usual 

 method, 0-108 grm. oxide of zinc. 



II. 0-430 grm. from another preparation lost at 100° C. 0-080 

 grm. water. The residue, dissolved in water and precipitated 

 with carbonate of potash, gave 0'119 grm. oxide of zinc. 



Hence in 100 parts, — j jj 



Water .... 18-23 18-60 



Zinc .... 23-57 22-21 



100 parts of lactate of zinc, prepared from the acid obtained 

 by fermentation, contain— ^.s jjio ZnS 0«+3IF O. 



Water 18-16 



Zinc 21-93 



The zinc-salt examined is therefore lactate of zinc ; the shape 

 of the crystals, as well as their other physical and chemical pro- 

 perties, agree with this conclusion, 5-244 grms. of a watery 

 solution saturated at 16° C, left, after evaporation and exposure 

 to a temperature of 100° C. till the weight of the crucible re- 

 mained constant, 0-118 grm. of residue. 100 parts of water at 

 16° C. dissolve, therefore, 2-30 parts of the dry lactate of zinc 

 prepared from glyceric acid. The Handbooks on organic che- 

 mistry state that the Z»-lactate of zinc requires 58 parts of cold 

 water for its solution. The temperature at which the experi- 

 ment was made is, however, not mentioned. 



In the mother-liquors from the lactate of lime and zinc no 

 other substances could be discovered. 



On the supposition that the glycerate of potash, under the 

 conditions related in this paper, is changed in a similar manner 

 by caustic potash as glyoxylate of lime is by slaked lime, we 

 should have the following equation for its decomposition : — 



2 (C3 H^ KO') -f KHO= C^ H^ KO^* -f C^ H^ K^ O'' + 2W 0. 



Glycerate of Lactate of 



potash. potash. 



* I employ for lactate of potash the formula C H^ K0\ in order to ex- 

 press the dccompositiou in the simplest manner. The formula of lactic 



