190*J.] PUBLIC DOCUMENT — No. 31. 141 



From the table one notes a range in total acidity of the feeds 

 tested varying from .00 to 1.21 per cent. The high percentages 

 were fonnd only in a few instances, the majority giving a range 

 of .30 to .80 per cent. 



By noting color and taste in connection with the determina- 

 tion of total acidity it was found that those feeds possessing a 

 dark or deep yellow color gave, in the majority of cases, a sharp 

 acid taste, and also a relatively high percentage of acid. The 

 relation which exists between depth of color and per cent, of 

 total acidity may be explained as follows: in the process of 

 manufacture there is, as heretofore stated, a certain amount of 

 steep water added to the gluten previous to drying. This steep 

 water carries a relatively high per cent, of acid, which nuist be 

 neutralized by the addition of soda or lime. It is the bleaching 

 action of the alkali which affects the depth of color ; if an insuf- 

 ficient amount of alkali were added to neutralize the acid pres- 

 ent there would be a relatively high acidity of the feed, together 

 with a comparatively deeper color, and vice versa. It should be 

 noted in connection with the above that while the addition of 

 the steep water to the gluten gives it naturally a darker color, yet 

 this should not be confused with the deep yellow color above 

 referred to, due to the artificial coloration. 



(h) Determination of Chlorides. 



Chlorides and sulfates were determined quantitatively in the 

 watery extract of many different samples. 



Method for Chlorides. — To 5 grams of the sample were 

 added 100 cubic centimeters of distilled water, as in the deter- 

 mination of total acidity. After shaking, the solution was 

 filtered and 20 cubic centimeters of the filtrate transferred to a 

 porcelain dish and titrated against N/lO sodium hydrate for 

 total acidity, using phenolphthalein as indicator. A few drops 

 of soda were then added to insure a slight excess, and the solu- 

 tion brought to dryness on a water bath, after which the dish 

 was transferred to a gauze top burner and the contents charred 

 at a low red heat. The finely pulverized contents were next 

 taken up with distilled water, filtered, and the insoluble residue 

 well washed with distilled water. The determination of chlo- 



