204 
O'Brien . — The Proteids of Wheat. 
is more soluble in hot water than in cold ; if precipitated by 
standing from its alcoholic solution, it, at first, disappears on 
heating. It gives the proteose reaction with nitric acid ; but the 
biuret reaction is doubtful, a violet tinge being always present. 
As it exists in the alcoholic solution, it is, however, obviously 
a hydrated proteid, which may be readily dehydrated by 
addition of alcohol or ether ; it cannot, therefore, have reached 
the proteose stage. It corresponds rather to an albuminate, 
using the word in the sense suggested by Weyl 23 and 
adopted by Osborne 33a , i.e. to a primary proteid hydrated 
by means either of water, acid, or alkali. Here the hydration 
is by means of the water in the dilute alcohol ; for if the acid 
present were sufficient to form an acid-albumin, this would be 
extracted from flour by water, which is not the case. A fur- 
ther degree of hydration is reached if the albuminate is allowed 
to stand with a large amount of water ; a degree of hydration 
which seems to correspond to that of gluten, as will be further 
discussed later. Finally, by boiling, the stage of coagulation 
is reached, and all but an inappreciable part may be made to 
coagulate (as is likewise the case with the ultimate constituents 
of gluten). Or the insoluble stage may be reached by evapo- 
ration in the cold and re-solution in dilute alcohol of as much 
of the proteid as will dissolve — a constantly diminishing quan- 
tity. In this, as in chemical behaviour, it resembles zein, 
which can be similarly made to pass into an insoluble form, in 
which it is unchanged in ultimate chemical composition (Chit- 
tenden and Osborne 41 ). 
The proteid extracted by 75°/ 0 alcohol, when dried at 
ordinary temperatures, forms a clear brittle glue-like mass. 
This is sometimes the case on drying at ioo° C.,but if a large 
amount of liquid has been used, the process is long enough for 
coagulation to occur in the watery solution towards the end of 
evaporation. During evaporation a sticky layer is deposited 
on the sides and bottom of the dish, and a pellicle forms on 
the surface (indicating the presence of myxon). The dried 
substance takes up water readily, forming a transparent, viscid 
mass somewhat resembling gluten : it is, however, more sticky, 
