EXPERIMENT STATION BULLETINS. 403 



0.0585 gram substance gave 5.0 cc. moist nitrogen (28°, 738 mm). 

 0.0291 gram substance gave 0.0072 gram CuO. 



Calculated for (C ^H , 2O ^N) ^Cu: N, 8.65; Cu, 19.64. Found: N, 9.10; Cu, 19.76 per cent. 



Isoleucine. — The combined methyl alcohol extracts from the leucine 

 were concentrated. After drying at 110°, the dark blue copper com- 

 pound analyzed as follows: 0.0539 gram substance gave 0.0133 gram 

 CuO. 



Calculated for (C^H , 2O2N) ^Cu: Cu, 19.64. Found, 19.72 per cent. 



After recrystallizing once from water, the copper was precipitated 

 by hydrogen sulfide and the solution concentrated. The pure, white 

 crystalline conii>ound was filtered from the mother liquor, washed with 

 alcohol and ether and dried at 110°. It melted at 272° when heated 

 quickly. It had the following specific rotation : 



In water, 0.3227 gram substance in 14.6053 grams solution (2.21 per 

 cent; 1.0053 sp. gr.) gave -)-l-l° (Ventzke) rotation in a 2 dm. tube 

 at 20°, sodium light. 



[af^ found = +8.58. 



on 



[a] for isoleucine = +9.74, 



In 20 per cent hydrochloric acid, 0.1965 gram substance in 13.4543 

 grams solution (1.46 per cent; 1.0871 sp. gr.) gave +3.25° (Ventzke) 

 rotation in a 2 dcm. tube at 20°, sodium light. 



[af^ found = + 35.47. 



[a]^ isoleucine = + 36.80. 



It analyzed as follows for nitrogen : 



Calculated for C6H13O2N: N, 10.68. Found: N, 10.89 per cent. 



From these results there can be no doubt as to the identity of the 

 two compounds in question. Both of them are well known decomposi- 

 tion products of protein and one of them, leucine, was among the com- 

 pounds isolated by Suzuki from humic acid. 



Experiments loith other Samples of Peat. 



As has been mentioned before,^ Jodidi determined the amounts of 

 mono — and diamino nitrogen in acid extracts of peat using phospho- 

 tungstic acid for precipitating the diamino acids. His conclusions were 

 based on the assumption that all acid-soluble nitrogen is in the form 

 of ammonium compounds, acid amides, mono — or diamino acids. 

 That this assumption is unwarranted seems probable from the fact that 

 many of the common constituents of plants, from which peat is formed, 

 are compounds in which some of the nitrogen is not in any one of 

 these four forms. To test this point analyses were made by Van 

 Slyke's method of samples of two of the peats used by Jodidi.^ In the 



ip. 11. 



2The conditions of extraction approximated 'as closely as possible those of Experiments 7 and 12, 

 Journ. Am. Chem. Soc. 32, 402; Tech. Bull. 4, 'Mich. Exp. Sta., Table I, p. 14. 



