NUTRITION — OSBORNE. 



203 



The substance, on rapid heating, decomposes at about 249° (uncorr.), 

 with evolution of gas, to a red oil. It forms a copper salt which crystallizes 

 in well-developed crystals belonging to the orthorhombic system, which on 

 prolonged exposure to dry air, lose water and disintegrate to a green powder. 

 As a consequence the water determinations were found somewhat below 

 that calculated for 3.5 molecules. 



Water : Calculated for CuHi80«N2Cu • 3.5 H2O 16.30 per cent. 



Found 15.74 per cent 



The composition of the water-free copper salt was found as follows : 



The crystals of this copper salt were measured for us by Prof. W. E. Ford, 

 of Yale University, who found that they belong to the orthorhombic system 

 and show the simple combinations of prism, m (100), macro-dome, d (loi), 

 and macro-pinacoid, a (100). 



The following angles were measured, those marked with an asterisk being 

 used as the fundamental angles from which the axial ratio was calculated : 



mf\m"' = 62". 31'* 



d/\d-- 

 i : b : c 



64°. 44'* 7nt\d^62°.S2' (calc. =62°46') 

 = 0.6071; 1. 00; 0.3848 



Under the microscope with crossed nicols the crystals showed parallel 

 extinction, confirming the crystallographic evidence of their orthorhombic 

 character. The free dipeptide is readily soluble in dilute acids and alkalies, 

 and gives the xanthoprotein reaction and pyrrol-test with a spruce splinter. 

 The substance is Igevo-rotatory in 20 per cent hydrochloric acid. Two obser- 

 vations gave — 



. 20° 



(a) -^ = —40.93° and —41.55° 



When hydrolyzed by heating its solution in 20 per cent hydrochloric acid 

 in a sealed tube for six hours at 118° to 125° it yielded 6y per cent of the 

 calculated quantity of pure phenylalanine and 107 per cent of nearly pure 

 proline. 



Proteins have been hydrolyzed with the results given in the table on p. 204. 

 For the details of methods of preparation of the proteins, the identification of 

 the products of hydrolysis and the methods of their separation, which were 

 conducted according to the well-known methods developed by Emil Fischer 

 and his colleagues, the publications listed in the bibliography in this volume 

 (pp. 46-54) may be consulted. 



An inspection of the table shows that a marked relation exists between the 

 botanical origin of the several proteins and the proportion of the different 

 decomposition products which they yield under the conditions of the analyses. 

 This relation is most marked in the case of the alcohol-soluble proteins of the 



