20 2 
O'Brien . — The Proteids of Wheat. 
extracted the proteid to be described later as the albuminate ; 
or more properly, it extracted glian from the gluten which 
must in each case have formed. 
No information is thus directly added as to the nature of 
gluten, but some facts about its origin are made clear, which 
will be considered later. 
C. Action of Alcohol. 
If gluten existed as such in flour, we should expect it to 
yield its glian-elements to alcohol ; finding that alcohol 
(76-8 o°/ o ) yielded only fat, Martin 35 concluded that not 
gluten, but some precursor of it, exists in flour. Ritthausen, 
however, found that with alcohol he could extract proteids of 
his third class (gluten-proteids) from flour. The amount 
extracted was from 4-3 to 5*i°/ 0 of the dry weight of flour. 
My results were somewhat higher. 
Alcohol ( 75 %) forms with flour a smooth paste whose want 
of elasticity indicates the non-formation of gluten. A larger 
quantity of alcohol extracts a proteid and leaves a residue 
which gives no gluten and no globulin. The absence of gluten 
in the residue is the result of the removal of the proteid, not 
of any inhibitive action of alcohol ; for flour moistened with 
75% alcohol, which was allowed to slowly evaporate, ulti- 
mately yielded the normal amount of gluten. The want of 
globulin is probably due to the coagulating effect of the 
alcohol, for the process of extraction is always a lengthy one. 
That the globulin is not extracted as such in the alcoholic 
solution is seen in the absence of any coagulum on heating. 
Salt-solution subsequently extracts a small amount of proteid ; 
it is precipitated by ammonium sulphate, but not by satura- 
tion with salt (NaCl) or by heat — agreeing with the proteose 
originally extracted by salt-solution or by water. 
The alcohol-extract contains a proteid, giving the xantho- 
proteic and Piotrowski’s reactions, and with Millon’s reagent 
a strongly coagulated precipitate which, like that in glian, 
does not colour deeply on heating. The proteid is not coagu- 
lated by heat ; it is precipitated by alcohol or water, but passes 
