660
mann carefully tested the accuracy of the method ‘by having different analysts send him small samples Dgo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.9010 0.8990 of beer, together with a statement of their density. 1,657’) Na”. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4586 .D. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -39.60’ -37.30’ From this and the refractometer reading taken by himAcid N o . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.52 3.60 self, Ackermann calculated the percentage of alcohol 9.09 11.4i Menthyl acetate, per cent. . . . . . . . . . . . and extract with the aid of his machine. Some of the Ester menthol, per cent. . . . . . . . . . . . . . 7.16 9.03 45 ,3A Ester menthol, per c e n t . . . . . . . . . . . . . 58.04 results obtained are discussed below. I t must be Total menthol, per c e n t . . . . . . . . . . . . . 54.41 65.20 stated t h a t this calculating apparatus was based upon 3 rols. Solubility ( 7 0 p e r c e n t alcoholat 20°C.. 3 vols tables which had been worked out from analytical IMPERIAL TOKYO UNIVERSITY data obtained by means of the pycnometer, and the T.KAMOI CAREPROF. JAPAN corrected alcohol and extract tables of Karl Windisch.1 -During the same year Bartha published a formula for determining the extract and alcohol in beer from THE USE OF THE IMMERSION REFRACTOMETER I N the specific gravity and the refractometer reading EXAMINING AMERICAN BEERS MADE FROM of the same. I n his article Barth published the reMALT AND UNMALTED CEREALS’ sults of 16 analyses, and to these we shall again refer B y ROBERTSCHWARZ below. The application of the immersion refractometer I n 1910 Danzer3 published a series of tables (also t o the analysis of numerous chemical solutions and based upon the alcohol and extract tables of Karl food products has attracted the attention of many in- Windisch) from which the alcohol and extract of any vestigators, and during the past 1 2 years quite a few beer could be calculated from the same determinaanalytical methods based upon the use of this instru- tions as those used in Ackermann’s method. As ment, together with valuable tables, have been pub- these tables are quite readily accessible, and the callished in various chemical journals. A considerable culations involved very simple, they put the refractopart of this work has been done by fermentation metric method of beer analysis within the reach of chemists, who quickly recognized the fact that the all chemists. immersion refractometer was especially well adapted The results published by Ackermann,4 and also for the analysis of the products obtained by the those given by Barth,s show but small differences wine grower, the distiller and the brewer. It is t o the between the percentage of alcohol and extract as dework done in the last mentioned field t h a t the author termined by the refractometer and the pycnometer. desires t o call special attention. It is therefore somewhat surprising t h a t the former Tornoe,* in 1897, published a method for the analysis method has not come into more general use by brewof beer which was partially based upon determining ing chemists. Particularly here in America, has the the index of refraction, using sodium light and a spe- immersion refractometer failed t o receive from the cially constructed type of differential refractometer. brewing chemists the attention which it so justly This method, while fairly rapid and quite accurate, deserves. Although the author has never found any direct did not, however, find wide application. written statement to the effect t h a t the method, as The introduction of the Zeiss immersion refractompublished by Ackermann, could not be applied t o eter, which is so extremely simple to manipulate, gave typical American beers which are brewed from a mixfresh impetus t o the study of optical methods for the ture containing 60-70 per cent malt and 40-30 per cent examination of liquids such as beer. I n 1903, Ackeradjuncts (in most instances unmalted cereals), some of mann and Spindlers published a method for determining our brewing chemists have informally expressed the t h e extract b y the formula E = (J - J’) 6 7 j o . in belief t h a t the results obtained with the refractometer which J = index of refraction of the beer, J’ = index on such American beers would not be sufficiently acof refraction of the distillate, and 6750 a n empirically curate to permit the use of this instrument. determined factor. I n this method the index of reThe writer, therefore, decided t o investigate this fraction of the beer and the distillate are calculated matter and examined, with the aid of the refractomfrom the immersion refractometer reading of these eter and the Danzer tables, 47 samples of beer and liquids. ale which iyere also analyzed by another chemist, I n 190j Ackermann4 constructed a calculating ma- using the official method, namely, distillation and dechine with which t o determine the percentage of alcohol termination of the specific gravity of the distillate and extract in beer from the density of the decar- and residue with the pycnometer. Attention must bonated beer, taken at I j / I j O C. and its refractori- be called to the fact t h a t in calculating the percenteter reading a t 17.5’ C. It is not the purpose ol ages of extract and alcohol equivalent t o the various this paper t o discuss the above publication other than densities found, the tables of Karl Windisch, and t o say t h a t this method is far simpler and much more not those given in Bulletin N o . 107, revised, Bureau rapid than the official pycnometer analysis. ,lcker- of Chemistry. LT.S. Dept. of Agriculture, were used. “Peppermint
oil”
“Purified peppermint oil”
Paper presented before the S e w York Section of the .lniericAn Chemical Society, Chemists’ Club, June 6, 19!3. 2 . f,d. ges. Brauuesen, 20, 373 (IS97 Ibzd., 26, 441 (1903:. 2. 1.d. ges. Brauwesen. 28, 33 (1905
These tables have been published in numerous journals and text books. I b i d . , 28, 303 \1905:8. 3 2 . f d. ges. B r a u z e s e u , 32 (1910 . .I See reference 3 j See reference 4. 1
2
T H E J O G R S A L O F I * V D U S T R I A L AiVD E&\-GIZ;EERISG CHE31ISTRY
Aug., 1913
The table for extract in beer, by H. Ellion, given in this Bulletin, gives the same values as t h e official Balling table, b u t as the figures in the latter are 0.07 per cent higher than those found in the Windisch table, a correction of -0.07 per cent. in the extract as determined b y the refractometer must be made when using either the Ellion or Balling table t o convert t h e specific gravity t o percentage of extract b y weight. The alcohol table of Gilpin, Drinkwater and SquibbI is about 0 . 0 2 per cent lower t h a n t h a t of I
