86 THE LACTIC ACID GROUP. 



readily in water, alcohol, and ether, attracts water from the atmo- 

 sphere, has a strongly acid taste and reaction, decomposes when 

 heated, and displaces not only volatile acids but even many of the 

 stronger mineral acids from their salts. Heated with concentrated 

 sulphuric acid, it yields almost pure carbonic oxide gas, and is con- 

 verted into a substance resembling humin; it gives, however, no 

 trace of formic acid. 



Composition. According to the above formula it consists of : 



Carbon 6 atoms .... 40'000 



Hydrogen 5 .... 5'555 



Oxygen 5 .... 44'445 



Water 1 .... 10-000 



100-000 



The atomic weight of the hypothetical anhydrous acid= 101 2'5, 

 and its saturating capacity =9*8 76. 



Combinations. With bases lactic acid generally forms neutral 

 salts, all of which are soluble in water, and many in alcohol, but 

 none in ether. Most of the lactates may be heated to 150 or 170, 

 and some even to 210, without undergoing decomposition. The 

 alkaline lactates are not crystallisable, and by the greatest concen- 

 tration can only be reduced to syrupy fluids ; and the same is the 

 case with the lactates of baryta, alumina, sesquioxide of iron, 

 and binoxide of tin ; but all other lactates crystallise with tolerable 

 facility, and are capable of resisting the action of the atmosphere. 

 The following peculiar relation has recently been observed in the 

 crystallisable lactates ; the lactic acid obtained from animal fluids, 

 and that produced by the fermentation of sugar, form, with the 

 same base, salts which present certain differences in the amount of 

 their water of crystallisation, in their degree of solubility, and in 

 their decomposition by heat, (Liebig,* Engelhardt and Maddrell,t 

 Engelhardt J). This is, however, a subject requiring further 

 investigation ; at least Liebig thinks that he has obtained from the 

 acid of Sauer-kraut a zinc-salt which corresponds with that yielded 

 by the muscular juice ; and in my own researches, whenever I 

 have analysed the lactic acid of the gastric juice in combination 

 with magnesia or zinc, I have always found it corresponding with 

 that obtained from sugar. Engelhardt distinguishes the acid 

 obtained from muscular juice as a lactic acid, and that produced 

 bythe fermentation of sugar as b lactic acid. 



Lactate of lime, CaO, La + 4HO, CaO. La-f 5HO, occurs in 



* Ann. d. Ch. u. Pharm. Bd. 62, S. 312. 

 f Ibid. Bd. 63, S. 83-120. 

 $ Ibid. Bd, 65, S. 359-366. 



