844
I N D USTRIA4LA N D ENGISEERING CHEMISTRY
pyrrole grouping is contained in small amounts in the majority of proteins, and i t forms a very important component of chlorophyl, the green coloring matter of plants which, as we shall see, is very closely related, chemically, to hemoglobin. I t is not improbable, therefore, that inorganic iron salts added to an exclusive milk diet are not utilized for building up hemoglobin simply for the reason that other component parts of the hemoglobin molecule as essential as iron itself are either lacking altogether in the milk diet or present therein in insufficient amount to subserve the needs of the blood-forming tissues and those of the other tissues as well.
The authors' work on milk powders and synthetic diets containing butter fat and cod-liver oil indicates that this statement must now be modified in the light of newer disroveries. Conclusion The following results of this investigation should be emphasized : I-Reproduction results obtained with cod-liver oil depend upon the manner in which the oil is administered.
Vol. 19, No. 7
2-Reproduction is much better on synthetic diets containing cod-liver oil than on synthetic diets with filtered butter fat. If the animals on the synthetic diet containing butter fat have a low hemoglobin content (and such may be the case) whereas those on cod-liver oil have a normal erythrocyte count and hemoglobin content, then there is present in cod-liver oil a specific vitamin which is required for normal iron metabolism. This conclusion is based on the supposition that the results of Hart, Steenbock, Elvehjem, and Waddell are correct-namely, that their animals suffering from anemia received a sufficient quantity of vitamins A, B, and C ; and that ultra-violet light did not remedy the condition. This problem is now under investigation in this laboratory and results d l be published when they are complete. Acknowledgment The writers desire to express their appreciation t o the Fleischmann Company for kindly supplying the yeast.
Estimation of Methanol in Alcohol and Alcoholic Beverages, Using the Immersion Refractometer' By John F. Williams
u. s. INTERNAL R E V E N U EB U R E A UBRANCH , LABORlTORY, BUFFALO, N.
Y.
This method is based upon the refractive indices of the alcohols, and the apparent total percentage of alcohol as ethyl alcoholfrom the speczJic graoity, using a 20 per cent solution. It is simple, rapid, accurate, and eliminates caZculations. CMEROUS methods have been proposed and used reading oi 41 35, and specific gravity 0 97513 (20°/4' C ) By the applicaof these figures t o the method given one will obtain a minus quantity for t'he estimation of methanol in alcohol, depending tion of 4 9 per cent of methanol generally upon chemical reactions. Among these Method are the Riche and Bardy method,2 which converts the alcohols into methyl and ethyl aniline dyes, comparing strips of wool The method given here depends upon finding the numeridyed by these products; the method of Thorpe and Holmesj3 cal difference between the immersion refractometer reading, which uses potassium bichromate and sulfuric acid t o oxidize R , and the exact percentage of total alcohol, P , calculated the methanol into water and carbon dioxide, and the esti- as ethyl alcohol from the specific gravity, using a 20 per cent mation of the latter; the method of Deniges-Simm~nds,~solution. Both the refractometer reading and the percentage which depends upon the colorimetric est'imation of the form- of total alcohol are taken on a 20 per cent alcoholic solution aldehyde oxidized from methanol; method based upon the of the original sample. That is, the original sample is estimation of formic acid oxidized from methanol; and diluted to 20 per cent total alcohol by volume. This is method depending upon combustion analysis. done by taking the specific gravity, as usual, on the distillate The method most universally used in this country is of the original sample, and assuming that all the alcohol that given by Leach and Lythgoe in 1905) based upon the present is ethyl alcohol, diluting a measured amount, repredifference in the indices of refraction between the two alcohols. senting 20 volumes of absolute alcohol, to 100 cc. On this The method is intended to be used with the Hehner Alcohol 20 per cent solution is then obtained the immersion refracTables 15.6"/15.6" C., but this fact was not' stated by the tometer reading, R, and also, from the specific gravity, the authors in their original article,fl and the method was un- exact percentage, P , of total alcohol by volume, calculated fortunately inserted, without revision, in the Methods of as ethyl alcohol. This last value may be slightly above Analysis, Association of Official Agricultural Chemists, 20 per cent, depending upon the amount of methanol present, 1919 and 1924, which uses the Bureau of Standards Alcohol as explained later. The percentage of methanol is then read Tables 2 O o , / 4 O C. This method will give an error of the off on a graph or table from the difference, R - P. A more methanol value of 4 to 5 per cent in some cases, mainly detailed description is given under Procedure. because of the difference in the two temperature standards. The method is designed to eliminate the inaccuracy, as well as the calculations necessary, in the method of Leach Noh-This f a c t may be shown abstractly b y assuming a pure ethyl alcohol solution, 15 per cent by weight, which will have a true refractometer and Lythgoe as printed in the h1ethods of Analysis, A. 0. A. C. The new method also takes into account the fact Printed b y permission of t h e Prohibi1 Received February 28, 1927. that when ethyl alcohol and methanol are diluted the specific tion Unit, U. S. Internal Revenue Bureau. 2 Compl. rend., 80, 1076 (1875). gravities do not run parallel. The difference between the 3 J . Chem. SOC.(London), 85, 1 (1904). specific gravities of the two are greater for dilute solutions 4 Simmonds, "Alcohol," p. 183 (1919). than for strong solutions. When a 20 per cent by volume 6 2. Xahr. Genussm., 24, 7 (1912). solution of pure methanol is calculated as ethyl alcohol, 6 J . A m . Chem. Soc., 27, 964 (1905).
N
I T D U S T R I A L 3 5 D E S G I S E E R I S G CHE-VISTRY
July, 1927
the apparent amount of ethyl alcohol is 21.5 per cent. When met'hanol is 100 per cent, however, and then calculated from the specific gravity as et,hyl alcohol, the apparent amount of ethyl alcohol is 99.4 per cent. Use is now also made of the accurate refractive indices published b y Doroshevskii and Dvorzhanchik in 1909,' the et'hyl alcohol indices of which hare been arranged by St'. John* and calculated to 20" C. for the immersion refractonieter readings. Good results are obtained even where 1per cent of methanol in ethyl alcohol is present, but where the sample contains less than that amount it is recommended that a set of colorimetric standards be made u p using the method outlined by SVright9 (or the method of Georgia and Moraleslo may be used). Traces of acetone or other substances have no appreciable effect upon the accuracy of the method. The method is rapid, for once the sample is reduced to 20 per cent by volume of tot'al alcohol, results may be obtained in 30 minutes. It is accurate to within 0.5 per cent of methanol in alcohol. Procedure
The percentage of alcohol in the original sample is obtained by the usual method from the specific gravity, and is recorded in terms of total alcohol by volume calculated as ethyl alcohol. The proper solution is obtained by pipetting a sufficient amount to give 20 volumes of absolute alcohol into a 100cc. volumetric flask, and diluting with distilled water to the mark. Both measuT*enients are made a t 20" C.
845 Table I
%::Fh:F$::f: R-P
AIxOHOL
% by volume
23.85 23.65 23,45 23.25 23.05 22.80 22.60 22,40 22.20
yi :: ;;::: 21.20
:!:A;
20.60 20,40 20.15 19.95
19.15
$I!: 18.5,5 18.35 18.15 17.95 17.75
i17.10 :;!
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0 20.0 21.0 22,0 23.0
;:::
26.0 27.0 28.0 29.0 30.0 31.0 32,0 33.0
Di:ggRR-P 16.90 16.70 16.50 16.30 16.10 15.90 15.70 15.50 15.30 15.10 14.90 14.70 14,50 14,30 14.05 13.85 13.65 13.45 13.25 13.05 12.85 12.65 12.45 12.25 12.05 11.85 11.65 11.45 31.25 11.00 10.80 10,60 10.40 10 20
'
~
%ALCOHOL by volume 34.0 35.0 36.0 37.0 38.0 39.0 40.0 41.0 42.0 43.0 44.0 45.0 46.0 47.0 48.0 49.0 50.0 51.0 52.0 53.0 54.0 55.0 56.0 57 .O 58.0 59.0 60.0 61.0 62.0 63.0 64.0 65.0 66.0 67.0
~
";I,"'g.I~ ~ ~
D ~ ~ ~ ~ ' E R -
R--P
70ALCOHOL b y volume
10.00 9.80 9.60 9.40 9.20 9.00 8.80 8.60 8.40 8.20 8.00 7.80 7.60 7.35
68.0 59.0
I
.In
6.95 6.75 6.55 6.35 6.15 5.95
5.z;
D.D.3
5.35 5.15 4.95 4.75 4.55 4.35 4.15 3.95 3.75 3.55
10.0
71.0 12.0 13.0 74.0 ,5.0 76.0 77.0 z8.0 ,9.0 80.0 81.0 82.0 83.0 84.0 85.0 86.0 87.0 88.0 89.0 90.0 91.0 02 0 93.0 94.0 95.0 96.0 07.0 98.0 99.0 100.0
The specific gravity determinations and refractometer readings were made a t about bhe same time to prevent loss
Example: Sample contains 61.7 per cent alcohol by volume 20.0 + 64.7 X 100 = 30.9 30.9 cc. made up t o 100 cc. with water = 20 per cent alcohol
The Zeiss immersion refractometer scale reading at' 20.0" C. is obtained on the prepared solution. This reading is called R. By use of a pycnometer 20"/4" C. on the same solution the exact percentage of alcohol by volume is obtained from the table for ethyl alcohol." This percentage is called P. Note-Depending upon t h e a m o u n t of methanol present this figure may be somewhat above 20.0 per cent. T h a t is, i t will be 20.0 per cent if t h e sample is ethyl alcohol, a n d increase i f methanol is also present, until t h e percentage will appear 21.5 per c e n t ethyl alcohol when only methanol is present.
The difference ( R - P ) indicates on the graph or table the percentage of methanol. The graph was plotted from results obtained on standards prepared by t,aking various mixtures of ethyl alcohol and methanol to give 20 cc. of total absolute alcohol, calculated from the specific gravity as ethyl alcohol, and diluting with distilled water to 100 cc. a t 20" C. The curve was then smoothed out somewhat to agree with the theoretical curve. 7
J. Russ. Phys.-Chem. SOC.,40, 908 (1909); C. A , , 3, 1358 (1909).
Assoc. Official Agr. Chem., Methods, Alcohol Tables, Zeiss Immersion Refractometer. 9 THISJ O U R X A L , 19, 750 (1927). 10 Ibid., 18, 304 (1926). 1 1 Assoc. Official Agr. Chem., Methods, Specific Gravity Alcohol Tables, 20°/40 C. 8
~
by evaporation of either portion. The standards were exposed no longer than 10 minutes in the refractometer beaker before taking readings. The specific gravities of the standards were obtained by 50-cc. pycnometers and the percentage of alcohol b y volume taken from the table for ethyl alcohol. l
Pan American Conference Urges Metric Standardization A decisive victory for the metric movement in the Vnited States was gained at the Pan American Standardization Conference, which recently closed its sessions in Washington, D . C. By resolution it was declared that the decimal metric weights and measures should be employed in trade between the United States and the republics of Latin America. "Manufacturers and exporters in the United States," i t was stated, "can extend more readily their operations in Latin America by offering their products in the same terms t h a t their competitors in Europe do." The fact was emphasized that all of the twenty Latin American republics use metric units, as do all the nations of continental Europe and the majority of other peoples. This decision is expected t o aid greatly the export trade of the United States with Latin America.
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