id="Footnote_2_2"/> [2] Precipitation and uniting, in the form of flakes, of the coagulable albuminoids, leaving the liquid clear.

METHODS OF ANALYSIS.

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]

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.

RESULTS OF ANALYSIS.

Tables I to IV contain the results of the analyses of the worts and finished fermented products obtained at the various breweries where this investigation was conducted, arranged so as to show readily the changes which took place during fermentation and, in a few cases, the changes which took place during storage. The results are all given in terms of grams per 100 cc, so that a direct comparison of the quantities of any particular ingredient in a definite volume of material may be made. The comparison of the grams per 100 cc of an ingredient in the wort, with the grams per 100 cc in the finished fermented product, is based on the assumption that there is no appreciable change in the volume of the wort during fermentation.

In Table I are given the results of the analyses of 7 malt worts and the beers produced from them. Table II contains the results of the analyses of 2 malt-and-rice worts and 2 malt-and-corn worts, and the beers produced from them. In Table III are given the results of the analyses of 4 porter worts and the finished porters produced from them. The results of the analyses of 9 ale worts and the finished ales are shown in Table IV. In these four tables the extract in the original wort has been calculated by multiplying the alcohol (expressed in terms of grams per 100 cc) by 2, and adding to the product the extract of the beer, porter, or ale (expressed in terms of grams per 100 cc). In the porter and ale worts a percentage of dextrose had been added as brewer's sugar. Since dextrose reduces more copper than does maltose in the determination of the sugars, in order to obtain the true percentage of total sugars it was necessary to calculate the amount of copper reduced by the known amount of dextrose present, and then to calculate the amount of maltose. The results thus obtained are given in Tables III and IV under the heading "Reducing sugars as anhydrous maltose."

Table I.—Analyses of all-malt worts and of the beers made from them.