LACTIC ACIDS. 585 



The phosphocarnic acid (SIEGFRIED) and the inosite are also considered 

 as possible mother-substances for sarcolactic acid. Further research 

 will show whether also other mother-substances for this acid occur. The 

 autolytic experiments of TURKEL 1 with livers and the formation of lactic 

 acid in the muscles, not from carbohydrates, inosite or alanine, as observer! 

 by EMBDEN 2 and his collaborators seem to indicate this. 



The lactic acids are amorphous. They have the appearance of 

 colorless or faintly yellowish, acid-reacting syrups, which mix in all pro- 

 portions with water, alcohol, or ether. The salts are soluble in water, 

 and most of them also in alcohol. The two acids are differentiated from 

 each other by therr different optical properties paralactic acid being 

 dextrogyrate, while fermentation lactic acid is optically inactive also 

 by their different solubilities and the different amounts of water of crys- 

 tallization cf the calcium and zinc salts. The zinc salt of fermentation 

 lactic acid dissolves in 58-63 parts of water at 14-15 C., and contains 

 18.18 per cent water of crystallization, corresponding to the formula, 

 Zn(C3H503)2+3H2O. The zinc salt of paralactic acid dissolves in 17.5 

 parts of water at the above temperature and contains ordinarily 12.9 

 per cent water, corresponding to the formula, Zn(C3H5O3)2+2H 2 0. 

 The calcium salt of fermentation lactic acid dissolves in 9.5 parts water 

 and contains 29.22 per cent ( = 5 molecules) water of crystallization, 

 while calcium paralactate dissolves in 12.4 parts water and contains 24.83 

 or 26.21 per cent ( = 4 or 4J molecules) water of crystallization. Both 

 calcium salts crystallize, not unlike tyrosine, in spears or tufts of very 

 fine microscopic needles. HOPPE-SEYLER and ARAKI, who have closely 

 studied the optical properties of the lactic acids and lactates, consider 

 the lithium salt as best suited for the preparation and quantitative estima- 

 tion of the lactic acids. The lithium salt contains 7.29 per cent Li. For 

 further information as to the salts and specific rotation of the lactic acids 

 see HOPPE-SEYLER-THIERFELDER'S Handbuch, 8. AufL, 1909 . 3 



Lactic acids may be detected in organs and tissues in the following 

 manner: After complete extraction with water, the protein is removed 

 by coagulation at boiling temperature and the addition of a small quan- 

 tity of sulphuric acid. The liquid is then exactly neutralized, while 

 boiling, with caustic baryta, and then evaporated to a syrup after filtra- 

 tion. The residue is precipitated with absolute alcohol, and the pre- 

 cipitate completely extracted with alcohol. The alcohol is entirely 

 distilled from the united alcoholic extracts, and the neutral residue is 



1 Tiirkel, Bioch. Zeitschr., 20. The statements on the formation of lactic acid 

 in the muscle autolysis are rather conflicting; see Fletcher, Journ. of Physiol., 43. 



2 Embden, Kalberlah and Engel, Bioch. Zeitschr. 45; Kondo, ibid., 45. 



3 See also E. Jungfleisch, Compt. Rend., 139, 140, and 142; Herzog and Slansky, 

 Zeitschr. f. physiol. Chem., 73. 



