11 



filter, wash thoroughly with boiling water till the washings are no longer 

 acid; remove the substance from the filter into the same beaker with 

 200 c. c. of hot 1.25 per cent solution of sodium hydrate, free of 

 sodium carbonate; boil for thirty minutes, filter through a gooch and 

 wash with boiling water till the washings are neutral; dry to constant 

 weight and incinerate after weighing. The loss in weight by inciner- 

 ation will give the quantity of crude or indigestible fiber. The most 

 convenient filtering material for the first filtration is line linen, although 

 any other method which secures a clear filtrate and rapid work may be 

 used. The strength of the solutions of acid and alkali should be accu- 

 rately determined by titration. 



NOTES .ON METHODS OF ANALYSIS. 



The total albuminoids are obtained by multiplying the percentage of 

 nitrogen found by 6.25. The starch and soluble carbohydrates, includ- 

 ing all bodies soluble in the reagents employed, are obtained by differ - 

 ence that is, the sum of the moisture, ash, ether extract, albuminoids, 

 and crude fiber subtracted from 100. The percentage of starch in this 

 material varies largely with different cereals and even with different 

 samples of the same cereal, but inasmuch as all these carbohydrate 

 bodies are supposed to have almost the same food value no attempt has 

 been made to separate them. 



In regard to the slight variations from standard methods which are 

 mentioned above, the only one of importance is that referring to the 

 determination of fiber. It is found in our experience here that heating 

 in beakers covered with watch glasses is quite as efficient as the method 

 prescribed by the association, and where so many samples are to be 

 examined the greater speed which is secured by doing away with the 

 process of directing a current of air on the foaming mass while boiling 

 is a matter of considerable importance. 



Another variation from the official method was in the determination 

 of moisture. At Chicago no facilities were afforded for the determina- 

 tion of moisture in a current of hydrogen. Experience has shown that 

 there is practically no difference in the analytical data secured on sam- 

 ples dried in the open air, in a partial vacuum and in a current of hydro- 

 gen, and for this reason the drying in the air, which is so much more 

 easily accomplished, has been followed. 



The methods used for moist and dry gluten have not been adopted 

 by the Association of Official Agricultural Chemists. They are the 

 processes which are used in this laboratory and which have given us 

 satisfactory results. The determination of moist and dry gluten can not 

 in any sense be regarded as an exact analytical process. For millers' 

 purposes, however, the numbers have considerable value, showing the 

 comparative percentage of glutinous matter in the different samples. 

 For obvious reasons the determination of dry and moist gluten was 

 confined to samples of wheat and wheaten flour. 



