74 CHEMICAL PHYSIOLOGY. 



separated. There remains on the muslin a greyish-white, 

 sticky elastic mass of "crude gluten," consisting of the 

 insoluble albumenoids, some of the ash, and the fats. Draw 

 out some of the gluten into threads, and observe its 

 tenacious characters. 



(/>.) Dry some of the gluten, and heat it strongly in a 

 test-tube ; an arnmoniacal odour similar to that of burned 

 feathers is evolved. Water, which is alkaline (due to 

 ammonia), condenses in the upper part of the tube. 



(c.) Extract 10 grms. of wheaten flour with 50 cc. of 

 water in a large flask. Shake it from time to time, and 

 allow it to stand for several hours. Filter. If the nitrate 

 is not quite clear, filter again. Heat a part of the clear 

 filtrate, and observe the coagulation of vegetable albumin. 



(d.} Test another portion of the nitrate from (c.) for the 

 xantho-proteic reaction. 



(e.) Another portion of (c.) is to be precipitated by acetic 

 acid and ferrocyanide of potassium. 



(/) Test a third portion of (c.) for the biuret reaction. 

 This is best seen on slightly heating. Take care not to boil 

 the liquid, or the reaction for sugar will be got instead. 



(g.) Extract some wheaten flour with a 10 per cent, solu- 

 tion of common salt for twelve hours. Filter, and drop 

 some of the clear filtrate into a large vessel of water ; a 

 milky precipitate of a globulin is obtained. 



(h.) On saturating some of the filtered saline extract of (g.) 

 with powdered NaCl or MgSO 4 , a precipitate of a globulin 

 is thrown down. 



(i.) Fats. Shake up some wheaten flour with ether in a 

 cylindrical stoppered vessel or test-tube, with a tight-fitting 

 cork. Allow the mixture to stand for an hour, shaking it 

 from time to time. Filter off the ether; place some of it on 

 a perfectly clean watch-glass, and allow it to evaporate spon- 

 taneously, when a greasy stain will be left. 



