METHODS OF ANALYSIS.

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The methods of analysis used were those given in Bulletin 107, revised (U. S. Dept. Agr., Bur. Chem.), pages 90-94, with the exception that the determination of phosphoric acid was made by the method used in fertilizer analysis (ibid., pp. 2-5), destroying the organic material in the beer by digestion with strong sulphuric acid and nitric acid and determining the phosphoric acid finally by the optional volumetric method (ibid., p. 4). The uranium acetate method given for beers was not used, for the reason that it was found to be exceedingly difficult to obtain accurate results on dark-colored beers. [1]

[1] Riley, in his report to the Association of Official Agricultural Chemists for the year 1913, stated that the method giving the most uniform results was that of ashing the beer with an excess of standard calcium acetate, and that while the moist combustion method in the hands of those familiar with it gave satisfactory results, the various collaborators working with the method did not get as uniform results as with the method of ashing with calcium acetate. J. Assoc. Off. Agr. Chemists 1 (1915), 138-143.

It was found in the estimation of dextrin by the Sachsse-Allihn method (ibid., p. 91) that there is an error in the method of calculation of the amount of dextrose formed from the amount of maltose in the original beer. Instead of multiplying the amount of maltose in the original beer by the factor 0.9, it should be multiplied by the factor 1.053, as 1 gram of anhydrous maltose yields, on hydrolysis, 1.053 grams of dextrose. The product is the quantity which should be subtracted from the total amount of dextrose found after hydrolysis. The extract in the beer was determined by use of the tables of Schultz and Ostermann (ibid., pp. 209-213). The same methods were used in the analyses of the worts as were used in the examination of the beers.

                                                                                                                                                                                                                                                                                                           

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