O'Brien . — The Proteids of Wheat. 189 
considers secondary, and this may well be the case here 
likewise. 
iii. Gluten . — This may be formed in fine strands on a slide 
under the microscope by adding a drop of water to a few 
grains of flour and moving the cover-glass over it. These 
strands give the usual proteid reactions and stain sharply with 
various aniline-dyes, e. g. methyl-violet and saffranin. The 
only at all characteristic stain that I can find is aniline-blue 
(W asserblau) or Hoffmann’s blue. On addition of either 
of these, freshly dissolved in water, the gluten-strand gradually 
colours and swells up, losing its sharp contour — probably 
owing to the acid nature of the reagent. These strands are 
otherwise singularly stable, being apparently unaffected by 
irrigation with solutions of sodium chloride, sodium phosphate, 
sodium carbonate, and even for some time with dilute potash. 
In acetic acid they swell up, but on washing or neutralisation 
appear as fine and complete as before : this is likewise the 
case with hydrochloric acid ; sulphuric acid acts more strongly, 
the gluten at first appearing fixed but soon dissolving, in the 
dilute acid or in concentrated. 
In obtaining gluten for quantitative estimation, my method 
was to add water at 30°C. to 10-15 grams of flour, till a stiff 
paste was formed. This was left to stand for an hour, and 
was then washed by moving it gently with a glass rod on 
a piece of muslin loosely stretched and dipping into a beaker 
of water at 30° C. ; there is thus no need to allow any particles 
of gluten to become isolated from the mass. The chief 
danger of loss is in the particles of gluten which necessarily 
adhere to the dish in which the paste is formed : they are 
best collected and washed, at first, independently of the rest. 
As the starch is removed, the gluten becomes sufficiently 
coherent to be held in the fingers, and may at this stage be 
washed under the tap. In a short time the gluten contracts 
to a tough mass ; in fact throughout the process it is becoming 
less viscid and elastic. Washing should be continued till 
the mass of damp gluten pressed on a slide leaves no starch- 
grains in a drop of water. The prepared Hungarian flour 
