12 



of dealcoholized beer, the value for A being determined from alcohol 

 tables accompanying the instrument. 



The extract determinations gave fairly concordant results. The 

 use of the immersion refractometer for this determination also gives 

 accurate results. The dehydration of maltose in the estimation of 

 extract by direct weighing is apparently more a theoretical than an 

 actual error. The determinations of extract and specific gravity of 

 wort by different analysts agree very well, the greatest error being 

 that introduced by the use of different tables. The formulas B, C, D, 

 and E offer no advantage over the more simple formula O=2A-j-E. 

 This formula is considered by brewers to express very nearly what 

 takes place in practice. 



Kremer a has made a careful study of the different formulas, employ- 

 ing them in eight experimental brews of different character. He 

 states that although the formula O 2A+E is not correct from a 

 scientific standpoint, since theoretically two parts of maltose are not 

 required to produce one part of alcohol, yet in practice it is the most 

 accurate. The specific gravity of the wort varies greatly according to 

 the table employed. Schultz and Ostermann's and Balling's tables agree 

 closely, Ell ion's tables giving somewhat higher results. 



The degree of fermentation calculated according to the formula 



900 A 



D= ^ gives entirely satisfactory results. The determination of 



total acids is not entirely satisfactory, since the end point with neutral 

 litmus paper is obscure. The use of phenolphthalein is suggested as 

 a preferable indicator. As the end point is reached a drop of the beer 

 is added to a drop of phenolphthalein on a porcelain plate; in this way 

 a sharp end point is readily obtainable. 



The volatile acid, as determined, did not give concordant results. 

 The error in the case of both total and volatile acids may be due to the 

 age of the sample when analysis was made. 



No comment is necessary in regard to reducing sugars, as the results 

 are entirely satisfactory. 



The same is true of the dextrin determinations. Good results are 



obtained by the use of the formula D = - " ^ Q - whenD= dextrin 



in grams per 100 cc; A, total rotation in degrees Ventzke in 200 mm 

 tube, and M, percentage of maltose as determined gravimetrically. 

 This formula is based upon the difference of optical activity of dextrin 

 and maltose, and its use furnishes a ready and accurate method for 

 determining a factor which is otherwise somewhat difficult to obtain. 



It is impossible to explain the differences in polarization obtained by 

 the various analysts, except on the assumption that the various instru- 

 ments were not in accord. 



The results of ash estimation are very close. 



The phosphoric acid results obtained, both yolumetrically and gravi- 

 metrically, agree very well. The volumetric method, with standard 

 uranium solution, is to be preferred on account of the rapidity with 

 which it may be used. 



Letters on Brewing, vol. 1, p. 9; vol. 1, No. 2, p. 19. 



[Clr. 33] 



