[macfarlane] constituents OF GLUTEN 19 



any particles to be expressed. After drying, the weight of the residt- 

 ing contents of the muslin gave the percentage, in duplicate, of the 

 crude glutenin contained in the flour. The weighing was done in the 

 muslin, the tare of which had been previously ascertained. 



4. The percentage of crude glutenin (3) subtracted from that of 

 the crude dry gluten (2) gave the percentage of loss which the gluten 

 had sustained by the treatment with alcohol, which loss is designated 

 as " crude gliadin.^' 



5. The aqueous solutions wnli the starch, from 20 grammes flour, 

 were mixed together, made up to 500 ccm. and allowed to stand until 

 the starch had subsided. 250 cc. of the supernatural liquid were then 

 filtered off and used for the determination of nitrogen and water-soluble 

 proteids. With respect to the starch deposit and its possible, though 

 unlikely, contents in particles of gluten, its treatment by the Kjeldahl 

 method was found to be exceedingly tedious, and the determination of 

 its nitrogen was abandoned. 



6 and 7. The alcoholic solution obtained as described under 3 was 

 evaporated to small bulk and its nitrogen estimated. This multiplied 

 by 5.7 gave pure gliadin (6), the percentage of which was always less 

 than the " crude gliadin " obtained as above described by difference. • 

 It is evident that 70 per cent alcohol dissolves, out of the gluten, other 

 substances besides gliadin, probably carbohydrates of the nature of 

 dextrine. Their amount was ascertained by deducting the percentage 

 of " pure gliadin " from that of " crude gliadin " and was designated 

 as " dextrinoids '' (7). 



8 and 9. In ''a similar manner the cake of dried crude glutenin 

 was Kjeldahlised and the amount of pure glutenin calculated from 

 the nitrogen. In making this determination the glutenin was not 

 removed from the muslin, and the latter underwent digestion in the 

 Kjeldahl process. The muslin was regarded as free from nitrogen. 

 A blank determination made with a piece of the muslin of same weight 

 as used for the gluten for ten grammes of flour, together with all ' the 

 reagents necessary in the Kjeldahl method, yielded only 0.00084 N". 

 = 0.00478' proteid, or 0.047 per cent on a sample of flour. The pure 

 glutenin foimd as above (8) deducted from the crude glutenin gave 

 a figure which I have designated as " non-proteids in crude glutenin " 

 (9). 



10. In this column is given the sum of the proteids determined 

 in the various products yielded by the flour, in order to compare it vrith 

 the total proteids found in the sample by direct examination. 



11. This column contains the difference between the sum of the 

 proteids in the different products obtained in examining the gluten and 

 the total proteids as calculated from the nitrogen in the original flour. 



12. For the sake of comparison the sum of the pure proteids (glia- 

 din and glutenin) contained in the crude gluten is given in column 12. 



