19 



V. Total solids. 



After extraction and final dilution cool slowly to about 20 C., shake thoroughly, allow to 

 stand for one hour, then pipette 100 cc into a tared dish, evaporate, dry, and weigh accord- 

 ing to method in Bulletin 46. 



VI. Soluble solids, nontannins and tannin. 



The determination of the above items should be conducted as by the method in Bulletin 

 46. 



NOTES. In all cases it is best to conduct the analyses from a dry basis that is, with the 

 material dried at 100 C. If the analysis is made to determine the tanning or commercial 

 value, results should be calculated back to the natural condition of the material. In the 

 case of analyses made for comparison between fresh and spent materials and in controlling 

 tannery or extract manufacturing processes results are more conveniently calculated and 

 recorded on a dry basis. 



Attention must be given to the quantity of hide powder used in determining nontannins. 

 See Paragraph III, Quantity of Sample, etc., above. 



The method for determination of acid in tannin solutions made pro- 

 visional in 1902 was continued as such with the following alternative 

 method : 



ALTERNATIVE PROVISIONAL METHOD FOR DETERMINATION OF ACID IN TANNIN SOLUTIONS. 



To 100 cc of diluted liquor, prepared as in the provisional method, add 2.5 grams chemically 

 pure animal charcoal, stir every fifteen minutes for two hours, filter, and titrate an aliquot 

 portion with decinormal alkali. 



Page 80, under " V. Soluble solids," change the last sentence to read 

 as follows: That the funnel shall be covered with a plate during 

 filtration, and all other means be taken to guard against evaporation. 



Twenty-second Convention, 1905, Bui. 99, Cir. 26. 



Under "VI. Nontannins" (addition of 1901), omit "this solution 

 to be added as follows: One-half at the beginning and the other half 

 at least six hours before the end of the digestion," and substitute 

 therefor, "at one time." 



In third sentence, after the word "press," insert "limiting the 

 moisture content of wet chromed hide powder used for analysis to 70 

 to 75 per cent." 



The following method for the analysis of liquors was adopted as 

 provisional : 



PROVISIONAL METHOD FOR THE ANALYSIS OF LIQUORS. 



X. ANALYSIS OF LIQUORS. 



Provisional method. 



Liquors must be diluted for analysis, so as to give as nearly as possible 0.7 grams of solids 

 per 100 cc. 



Total solids to be determined as in extract analysis. 



Soluble solids determination to be made in the same manner as with solutions of extracts. 



