290 FOOD AND FOOD ADULTERANTS. 



age of albuminoids. Graham determines tbe nitrogen by " Wank- 

 lyuiziug" the beer as in water analysis. The determination of the 

 nitrogenous matters in beer is important in enabling the analyst to 

 form an opinion on the question whether substitutes for malt were used 

 in its manufacture, as saccharine matter derived from sources other 

 than grain have little nitrogenous content. Too large an amount of 

 albuminous matter is injurious to the keeping qualities of the beer. 



The Kjeldahl 1 method, which was originally devised by its inventor 

 for application to the determination of nitrogen in beers and worts, may 

 also be used. 



FKEE ACIDS. 



The ideas of chemists in regard to the nature of the acidity of nor- 

 mal beer have undergone considerable change in the last two or three 

 years. It was formerly considered to be principally due to the pres- 

 ence of lactic acid, with a small quantity of succiuic and other acids, 

 but is now considered to be due, for the greater part, to acid phos- 

 phates. Acetic acid is present only to a very limited extent in normal 

 beer, its presence in any considerable quantities being proof of the 

 "souring" of the beer. Ott 2 has shown the difficulty of ascertaining 

 the exact point of neutralization in beer, as by the addition of alkali 

 to the acid phosphates the reaction becomes " amphoteric " from the 

 simultaneous formation of both primary and secondary phosphates, 

 and the establishment of the point of neutralization by the reaction 

 with litmus paper is very difficult. No better means of determining 

 acidity in beer has been proposed, however, and I have used the ordi- 

 nary method of adding standard alkali until a drop placed on neutral 

 litmus paper produces no alteration of color. 50cc are conveniently 

 taken for this determination, freed from carbonic acid and titrated with 

 decinormal alkali. The acidity can be given directly as cubic centime- 

 ters of normal alkali required for lOOcc. ot beer, or reckoned as lactic 

 acid. The volatile acids, when it is necessary to determine them sep- 

 arately, as in the case of soured beer, may be best estimated by dis- 

 tillation in a current of steam, as described under wine, all methods 

 for their estimation by difference by evaporating the beer to dryness 

 and titrating the residue having been shown to be faulty. 



The Bavarian chemists, 3 at their last meeting in 18SII, adopted the 

 figure of 3cc. normal alkali for lOOcc. beer as a maximum limit for a 

 normal beer. 



ASH. 



The ash may best be determined by burning the residue from 100 

 cc. of beer at a very low red heat in a innlHc. The a-sh obtained 



'Zeit. Anal. Chein. 1883,366, for reference to the modifications of the method, see 

 Bulletin No. 12, U. S. Depart. Agriculture, Division of Chemistry, p. 55. 



Zi-it, Anal. Cliein. 24,132. 



3 Ber. U. d. fh'nfto Ver. der Freien Verein Bay. Ver. d. aii.nrwaiidtrn Clirm. xu. 

 Wiirzbnrg, Berlin, 1887. 



