The saccharine matter in beer consists principally of maltose and dextrin, with probably a small proportion of dextrose. The greater part of the entire extract is composed of these different carbohydrates. The proportion of maltose to dextrin is of considerable importance in judging of the quality of a beer. The dextrin contributes to the "fullness" (vollmundigkeit) of the taste, and a larger proportion of dextrin to extract makes a beer of good "body." The method of brewing is said to have an important influence upon the relative proportions of maltose and dextrin. The determination of the percentages of these sugars is, therefore, quite an important one as showing the nature and quality of the sample, though not of much utility in detecting adulterations. The usual method is to estimate the maltose by Fehling's solution, and the dextrin, if it is reported at all, is obtained by difference from the total solids. So little is known of the saccharine bodies already existing in the grain and of the products of the conversion of starch into sugars, that their separate estimation is rather unsatisfactory.1 The dextrin may be determined directly by precipitating with alcohol, washing and weighing. The results are sufficiently accurate for commercial purposes, according to J. West Knights,2 who employed it upon worts.

Graham estimates the maltose and dextrin in beer worts by the use of Fehling's solution before and after inversion.3 The cupric oxide reducing power is determined gravimetrically, 10cc. are measured out and diluted to 100cc.; 20cc. of this solution are used to 30cc. Fehling's solution. The weight of CuO obtained, multiplied by 0.7314 gives the amount of maltese in the quantity of diluted liquid employed. The maltose having been determined, l0cc. of the wort are mixed with 3cc. of sulphuric acid, diluted to l00cc. and inverted by heating to 100° C., for 3 to 4 hours in a flask furnished with a long tube. The volume of the solution is again made up to l00cc., l0cc. carefully measured or weighed, neutralized with sodium carbonate, and the reducing power determined by heating with Fehling's solution, in the same way as before. The percentage of dextrin is then calculated as follows: Multiply half the weight of CuO, obtained by the action of Fehling's solution on 2cc. of the original wort by 1.72, and subtract the product from the CuO obtained from the inverted solution (= 1cc. of the original). The difference multiplied by 40.8 gives the grams of dextrin in l00cc. of the original wort.

This method was applied to the samples analyzed with very unsatisfactory results. In some cases the sum of the maltose and dextrin determined in this way exceeded the amount of total extract, while in other cases the per cent. of dextrin was a minus quantity. This method was therefore abandoned. The results given were obtained by the following method taken from Allen.1 The maltose was estimated by Fehling's solution, volumetrically, by the method in use in this laboratory for the determination of cupric oxide reducing power.2 The polarization is then observed in the original beer, the clarification being accomplished by means of lead acetate. The reading is taken on the circular scale, and constitutes the total circular rotation. The number of grams of maltose in 100cc. of the beer having been ascertained from the results obtained with Fehling's solution, it is multiplied by 2.78, which gives the rotation due to maltose; this result is deducted from the total rotation, which gives the rotation due to dextrin. The angle found, divided by 3.8G or multiplied by .259, gives the grams of dextrin in l00cc of the solution. These figures are based on the assumption that the polariscope used is one in which monochromatic light is employed, and that the liquid is observed in a tube 200 millimeters in length. By dividing the grams per l00cc. by the density of the beer, the actual percentage of maltose and dextrin will be ascertained.

1 Recent work on this problem has been published by O'Sullivan, Jour. Chem. Soc., Jan., 1886, p. 58. 2Allen's Organic Analysis 1, 274. 3Analyst 7, 211.

As considerable interest is attached to the nature of the polarizing bodies in malt liquors, I append the polarization given by the samples examined. It is a very easy and satisfactory determination to make, the beers being readily clarified by acetate of lead, giving bright, clear solutions. The figures given are in divisions of the cane-sugar scale, and for the normal beer, the dilution of one-tenth incident upon the addition of the lead being corrected by reading in a 220-millimeter tube; the instrument employed was a Laurent polariscope, in which monochromatic light is employed.

The polarization was in all cases right-handed.