xi THE ALBUMINOIDS : GELATINE 559 



possesses a low heat value, for the latter, according to Berthelot and 

 Stohmann, 1 is 500-700 calories smaller than in the case of most other 

 albuminous substances. 



The study of the dissociation-products of gelatine dates back to 

 1820, when Braconnot 2 showed that gelatine is rich in 'glycocoll' or 

 'sweat-glue.' This compound amounts, according to E. Fischer, 3 to 

 16 -5 per cent. In addition, gelatine contains large amounts of 

 glutaminic acid, pyrrolidin- and oxy-pyrrolidin carboxylic acids, and 

 also arginin and lysin. 4 It is poor, however, in histidin, and of the 

 three aromatic compounds it possesses only phenylalanin, as both 

 tyrosin and tryptophane are absent. The amount of phenylalanin is 

 without doubt much higher 5 than the figures of Fischer lead one 

 to suppose. The absence of Millon's reaction was already noticed by 

 the older investigators ; later on Maly 6 and Nencki 7 missed the 

 derivatives of tyrosin and also indol ; that, notwithstanding this fact, 

 aromatic compounds were found was one of the first indications of the 

 occurrence of phenylalanin in albumins. 



Maly 8 by oxidising gelatine with potassium permanganate + caustic 

 potash obtained the oxyprot-sulphonic acids discussed on p. 237. 



On oxidising gelatine by means of permanganates, especially by 

 calcium permanganate 9 in boiling solutions, Kutscher and Zickgraf, 10 

 and Zickgraf 11 obtained a substance which, according to Seemann, 12 is 

 oxaluramid or oxalan C 3 H 5 N 3 3 = NH 2 CO NH C 2 O 2 NH 2 (oxal- 

 uric acid or C 3 H 4 N 2 4 = NH 2 CO 'NH 'V 2 2 ' OH) ; Kutscher and 

 Schenck, 13 in addition to oxalan, observed also ammonium oxaminate, 



1 F. Stohmann and H. Langbein, Journ. f. prakt. Chem. [2] 44. 336 (1891). 



2 H. Braconnot, Ann. de Chim. et de Phys. 13 113 (1820). 



3 E. Fischer, P. A. Levene, and R. H. Aclers, Zeitschr. /. physiol. Chem. 35. 70 

 (1902). 



4 A. Kossel and F. Kutscher, ibid. 31. 165 (1900) ; W. Hausniaun, ibid. 27. 

 95 (1899). 



5 K. Spiro, Hofmeister's Beitrage, 1. 347 (1901) ; V. Ducceschi, ibid. 1. 339 

 (1901) ; R. Maly, Monatshefte f. Chem. 1O. 26 (1889) ; M. Nencki, Ber. d. deutsch. 

 chem. Ges. 7. II. 1593 (1874) ; L. Selitrenny, Monatshefte f. Chemie, 1O. 908 

 (1889). 



6 R. Maly, ibid. 10. 26 (1889). 



7 M. Nencki, Ber. d. deutsch. chem. Ges. 7. II. 1593 (1874) ; L. Selitrenny, 

 Monats. f. Chem. 10. 908 (1889). 



8 R. Maly, ibid. 10. 26 (1889). 



9 The permanganates of the alkaline earths (viz. barium permanganate) were first 

 used by Steudel, Zeit. f. physiol. Chem. 32. 241 (1901). 



10 Kutscher and Zickgraf, Sitzb. d. kgl. preuss. Akad. d. Wiss. May 28, 1903. 



11 G. Zickgraf, Die Oxydation des Leims mil Permanganaten. Inaugural Dissertation, 

 Marburg, 1904 ; and also in Zeitsch. f. physiol. Chem. 41. 259 (1904). 



12 J. Seemann, Zentralbl.f. Physiol. 18. 285 (1904). 



13 Kutscher and Martin Schenck, Bet. d. deutsch. chem. Ges. 37. 2928 (1904). 



