36 CHEMICAL CONSTITUENTS OF BOD Y AND FOOD. 
Accordingly, amido-compounds, leucines (C m H._> m+1 XO.,), and leuce'ines 
(CnHon^^Oo), were mixed with about 10 per cent, of urea, and finely 
powdered. The mixture was dried at 110 3 C., intimately mixed with 1*5 
times its weight of phosphoric anhydride, and heated in an oil bath. At 
120° C. there is no change; at 125° dehydration takes place rapidly, and 
the mixture becomes pasty, but solidifies to a compact solid mass without any 
darkening. This is dissolved in water, the solution mixed with excess of 
alcohol, and the pasty precipitate so produced washed with alcohol and 
re-dissolved in water. Phosphoric acid is removed by baryta, and the filtered 
liquid when concentrated yields an amorphous product soluble in water, but 
precipitated in a curdy form on the addition of alcohol. 
Aqueous solutions of this product are precipitable by most of the other preei- 
pitants of proteids ; it gives the biuret and the xanthoproteic reactions. When 
burnt it gives the characteristic odour of burning nitrogenous animal matter. 
The product he obtained does not give all the proteid reactions; 
it is, for instance, not precipitable by acetic acid and ferrocyanide of 
potassium ; and the evidence as to its proteid nature is otherwise hardly 
conclusive, because the colour tests for proteids are given by many of 
the decomposition products of albuminous matter. The partial success 
obtained will, however, point the way for future attempts, and so far 
as it goes, is in favour of Schiitzenberger's urcicle theory of proteid 
constitution. Complete success could hardly have been anticipated 
from such an experiment, because no means were taken to ensure the 
presence of sulphur, an element present in all proteids. Moreover, 
in the synthesis, no aromatic substance was introduced ; this, how- 
ever, is not absolutely necessary, as the formation of aromatic from 
fatty compounds by heat is a familiar chemical change (see p. 34). 
GHmavx's experiments. — Some years previous to Schiitzenberger's 
work, Grimaux l had obtained, by somewhat simpler processes, substances 
which even more resembled proteids in their reactions than Schiitzen- 
berger's. He was engaged in studying the properties of certain sub- 
stances, inorganic and organic, which lie termed " colloides," and of those 
which he prepared the three which especially bear on the present 
question are the following : — 
(a) Golloide amidohcnzoique. — This is made by heating, to 125° C, 
meta-amidobenzoic acid in a sealed tube, with one and a half times its 
weight of phosphorus pentachloride, for ninety minutes. The product is 
a white friable powder; this is washed repeatedly with boiling water to 
remove all phosphoric acid. The remaining substance Grimaux supposes 
to be an intramolecular anhydride, formed by the union of several mole- 
cules of meta-amidobenzoic acid, with the elimination of water. "When 
ammonia is added, it dissolves slowly in the cold, but rapidly on heating. 
The solution obtained is evaporated in vacuo, at a low temperature, and 
the resulting solid is a transparent jelly which dries into translucent, 
yellowish plates, which in their physical properties resemble dried 
serum albumin. 
(b) A colloid which is similarly prepared, except that the temperature 
in the sealed tube is allowed to rise to 135 c C. 
(c) Golloide aspartique. — This is made by the action of a current of 
gaseous ammonia on solid aspartic anhydride, heated to 170° 0. The 
1 Gom P L rend - -dead- d. sc., Paris, tome xciii. p. 771 ; xcvii. pp. 231, 1336, 1434, 1485, 
1540, 1578 ; Rev, scient., Paris. April 18, 1886 ; this article gives a summary of the other 
papers. 
