240 PHYSICAL AND CHEMICAL PROPERTIES OF LEUCINE. [BOOK II. 



to be composed of balls and nodular masses. These balls of leucine 

 are fairly transparent and sometimes present a radiated structure. 



FIG. 15. LEUCINE IN THE FORM WHICH IT USUALLY ASSUMES WHEN SEPARATED FROM 

 THE PRODUCTS OF DIGESTION BY TRYPSIN. 



Density. 



Although crystals of leucine float on water the 

 body is really of higher specific gravity than water. 

 According to Engel and Vilmain, the specific gravity of leucine at 

 18 C. is 1-293. 



Solubility. 



Leucine, as has already been stated, presents con- 

 siderable variations in certain of its physical properties 

 according to its origin and perhaps to the mode of preparation 

 employed. These differences are explicable on the hypothesis of the 

 existence of several leucines possessing the same chemical constitution, 

 but which are, however, ' physically isomeric.' Thus Zollikofer 1 

 found that 1 part of leucine obtained from lig. nuchae is soluble in 

 27 parts of cold water. B. Gmelin 2 found that 1 part of leucine 

 prepared from casein is soluble in 29 parts of water at the tempera- 

 ture of 19 C., and in 14'3 parts of boiling water, whilst 1 part of 

 leucine prepared from haemoglobin requires 45*8 parts of water at 

 19 C. to dissolve it, and 18' 7 parts of boiling water. 



Leucine obtained by the synthetic process described at page 238 

 requires 117 parts of water at the temperature of 12 C. to dissolve 

 it 3 . Leucines of approximately the same sparing solubility result 

 from the decomposition of various proteids by Schiitzenberger's 

 method 4 . 



1 Zollikofer, 'Beitrage zur Kenntniss d. elastisch. Gewebes.' Ann. d. Chem. u. 

 Pharm., Vol. LXXXII. (1852), p. 162180. 



2 B. Gmelin, op. cit. p. 30. 



3 Hiifner, Journ.f. prakt. Chemie (2), 1, 6. 



4 Refer to the memoirs of Schulze referred to at page 241. 



