4 6 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 
is quite in accordance with Sabanejeff's 1 cryoscopic determination of the 
molecular weights of these substances: he gives the molecular weight 
of protoproteose as 2467 to 2640, of deuteroproteose as 3200, and of 
peptone as 400 or less. The diffusion power of the different sub- 
stances investigated by Kuhne was as follows : — Heteroproteose is 
the least diffusible of the proteoses ; in neutral saline solutions it is 
precipitated as the salt passes out, and none goes through the dialyser ; 
dissolved in ammonia it loses 5 - 22 per cent. Deuteroproteose comes 
next (loss, 241 per cent.) ; then protoproteose (loss, 28-3 per cent.) ; 
while peptone loses 51 to 51 - 8 per cent. Each experiment lasted 
twenty-four hours. 
Action on polarised light. — All the proteids are levorotatory. The 
specific rotatory power of some of the principal members of the group 
is as follows : — ■ 
Proteids. ■ 
Observer. 
Value of («)d. 
Serum albumin ...... 
Egg albumin ...... 
Lact-albumin ...... 
Serum globulin ...... 
Fibrinogen ....... 
Alkali albumin ...... 
Syntonin (prepared from myosin). 
Casein (dissolved in MgS0 4 solution) . 
Various proteoses ...... 
\ Hoppe-Seyler 2 
j Starke 3 
i Hoppe-Seyler 
/ Haas 4 , Starke 
Sebelien 5 
Haas 
Herrman '' 
Haas 
Hoppe-Seyler 
Hoppe-Seyler 
Kuline and Chittenden 7 
-56° 
-68° 
-35°-5 
-38° -08 
-36 c -37° 
-59°'75 
-43° 
-62°-2 
-72° 
-80° 
- 70°-80° 
Colour reactions. — These are numerous, and doubtless depend for their 
occurrence on the various radicles which, as we have seen, are probably 
present in the proteid molecules. Many of them are given by certain of 
the decomposition products of the proteids; and by a careful comparison 
of these simpler substances, conclusions have been reached concerning the 
particular groups in the proteid molecule to which each reaction is due. 
Tbe majority of the colour tests are due to the presence of the 
aromatic radicle; it will, therefore, be well to preface the description of 
the reactions themselves by a classification of the aromatic substances 
derived from proteids by putrefaction. Salkowski 8 arranges them into 
three groups ; whether all these groups exist pre-formed in the proteid 
molecule, or are derived, as Maly considered, from only one aromatic 
group, matters but little in the question under investigation. The 
groups are as follows : — 
First group — The phenol group. — This includes tyrosine, the aromatic 
hydroxy acids, phenol, and cresol. 
Second group — The phenyl group. — This includes phenylacetic and 
phenylpropionic acids. 
1 Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xxvi. S. 
2 Ztschr.f. Chem., Leipzig, 1864, S. 737. 
3 Jahresb. it. d. Fortschr. d. Thicr-Chem., Wiesbaden, 
4 Arch. f. d. ges. Physiol., Bonn, Bd. xii. S. 378 ; 
S. 295, 811, 824. ' 
5 Jahresb. ii. d. Fortschr. d. Thier-Chem., "Wiesbaden, Bd. xv. S. 1S4. 
a Ztschr.f. physiol. Chem., Strassburg, Bd. xi. S. 508. 
7 Ztschr.f. Biol., Munchen, Bd. xx. S. 51. 
s Ztschr.f. physiol. Chem., Strassburg, Bd, xii, S. 215, 
385. 
Bd. xi 
Chem. 
S. 17. 
Cewtr.-Bl. 
Leipzig, 1876, 
