vin HEAT OF COMBUSTION AND ROTATORY POWER 329 



molecular weight of globin, i.e. the albumin-radical of haemoglobin, may 

 of course be very much less, as we do not know whether the colour- 

 radical, the haematin, is joined up with one or with several molecules 

 of globin. But the ratios of the dissociation-products to one another 

 and the equivalent weights according to Griibler, 1 Laqueur and 

 Sackur, 2 Harnack, 3 and Werigo, 4 also yield a molecular weight of 

 5000-8000, and even more. 



The direct methods of determining molecular weight we cannot 

 make use of, as raising of the boiling-point leads to heat-coagulation. 

 The lowering of the freezing-point method has yielded in the hands of 

 Sabanajew and Alexandrow, 5 for egg-albumin the molecular weight of 

 14,270. Here again the admixture of inorganic salts, which is quite 

 unavoidable, makes itself felt very badly; taking into consideration 

 the high molecular weight and the slight solubility of albumins, 

 the figures which have been obtained have never been higher than 

 could be accounted for by the presence of the inorganic salts alone. 

 Starling's 6 attempt of estimating directly the osmotic pressure of 

 albuminous solutions is also bound up with too many experi- 

 mental errors. There can, however, be no doubt that the colloidal 

 albumins possess an extraordinarily high molecular weight, and even 

 the albumoses, judging by their sulphur -content, possess at least a 

 molecular weight of 2000, while that of gluto-kyrin, a peptone, is at 

 least 545. 



The heat of combustion has been determined for a number of 

 albumins by Stohmann and Langbein. 7 They found amongst others 

 for 1 grm. serum-albumin, 5917*8 cal.; for haemoglobin, 5885*1 cal.; 

 for egg-albumin, 5735*2 cal. ; for casein, 5867 cal. ; and for glutin, 

 500 to 700 cal. less. 



The true albumins, the albumoses, and the peptones are in watery 

 solutions laevo-rotatory, each albumin possessing its own rotatory power, 

 and therefore Fre"dericq, 8 Kiihne, 9 and others have made the attempt to 

 make use of the rotatory power for the characterisation of the in- 



1 G. Griibler, Journ. f. prakt. Chem. [2] 23. 97 (1881). 



2 E. Laqueur and 0. Sackur, Hofmeister's Beitrage, 3. 193 (1902). 



3 E. Harnack, Zeitschr. f. physiol. Chem. 5. 178 (1881). 



4 B. Werigo, Pfliigers Arch. f. d. ges. Phys. 48. 127 (1891). 



5 A. Sabaiiajew and N. Alexandrow, Journ. of the Russian Phys.-Chem. Society, 

 1891, p. 7 ; see Malys Jahresber. f. TiercJiemie, 21. 11 (1891). 



6 E. H. Starling, 'Glomerular Function,' Journ. of Physiol. 24. 257 (1899). 



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



8 L. Fredericq, Arch, de Biol. 1. 457 (1880) ; II. p. 379 (1881). 



9 W. Kiihne and R. H. Chittenden, Zeitschr. f. Biol. 20. 11 (1884). 



