O' Brien . — The Proteids of Wheat. 185 
of peptone is precluded : the proteids present must therefore 
be globulin and proteose respectively. 
Thus, as obtained by water, the proteids of wheat are : 
| Soluble in water j 
( Insoluble in water 
ppt d . by boiling . . 
remaining in solution 
i. globulin 
ii. proteose 
iii. gluten. 
However, these apparently simple facts by no means explain 
the whole matter, since the amount of gluten obtainable from 
even the same flour seems to vary with varying conditions. 
Thus we are told that the yield of gluten is increased by 
allowing the paste to stand for some time before washing it 
(Benard and Girardin 29 , Balland 32 ) ; or by the use of ‘ hard ’ 
rather than of pure water (Ritthausen 22 ) : whilst heating of 
the flour to 6o°C., or extraction of it with salt-solution (NaCl 
I 5°/o) (Weyl and Bischoff 28 ), or with ether (Peligot 15 ), are 
alike said to prevent the subsequent formation of gluten on 
addition of water. 
1 . Globulin of Flour. In order to allow the water equal 
access to every particle of flour, so as to obtain the greatest 
possible amount of water-soluble proteid, the flour was care- 
fully sifted through muslin into the water. Even with this 
precaution gluten formed instantaneously, but it could readily 
be removed from the liquid by filtration after the starch had 
been allowed to settle to the bottom. Globulin was obtained 
by coagulation of the filtrate by heat as a flocculent white 
precipitate, drying to a brownish, brittle, semi-transparent, 
horny mass ; or, if the boiling has been prolonged, to a 
greyish-white, powdery substance. It swells up on the 
addition of water or alcohol (75%) to a somewhat viscid mass. 
It is difficult to collect and estimate, but seems to form 
about 1 % of the weight of the flour : i*io% was the amount 
obtained by extraction with water, i-oi°/ by extraction 
with NaCl. 
The coagulation by heat is accomplished in two stages : 
about 55°C. a milkiness or cloudiness appears, indicating 
myosin ; when this is removed by filtering, the solution may 
be kept at 6o°C. for some hours without further coagulation 
