As a means of shedding some light on the differences occurring in titrating wines with the two indicators, the determinations shown in the following table have been carried out:

Comparison of litmus and phenolphthalein as indicators in titrating some of the organic acids existing in wines.

The results shown for volatile acids by the Windisch method (p. 22) are somewhat higher than those obtained by the proposed new method, using phenolphthalein. Such discrepancies, however, lose their significance when it is considered that in the determination of volatile acids by the indirect method not only are the results of the titrations employing litmus as indicator incorrect, but the titrations of total and fixed acids are not made under comparable conditions. While it is unquestionably true that the volatile acids may be completely driven off by repeated evaporation in an open dish, it does not follow that the results obtained by means of the two titrations are correct. It is conceivable that important changes may occur during the prolonged heating of the wine in order to reduce the material a third time to a pasty consistency. At any rate, we have no positive knowledge that the so-called fixed acids occurring in the final residue represent the actual fixed acids in the original wine. A titration of the residue may suffice as an indication of the acids remaining after driving off the volatile constituents by prolonged heating, but to employ the result of such a titration as a factor in the calculation of the actual volatile acids appears to be an unwarranted proceeding.

In expressing results of analysis the orthodox custom appears to be to calculate the fixed and total acids as tartaric and the volatile acids as acetic. It is impossible to concede any advantages in favor of this custom. It may be safe to assume that in wines the fixed acids are in the main tartaric and the volatile acids acetic; but, even on such assumptions, the results are strictly erroneous and not readily comprehended. Such a method applied to the various fruit juices and ciders would fail to give significant results in practically all cases, and the case is still worse when one adopts the method of calculating the acids as sulphuric. Instead of these conventional methods it has been found better to adopt the plan of expressing all results for total, volatile, and fixed acids in terms of the number of cubic centimeters of normal acid in a definite measure, say 100 cc, of wine. There will then be afforded results which can be readily compared and comprehended. Furthermore, in case it be required to calculate results in terms of any particular acid, such an operation can easily be carried out.

RECOMMENDATIONS.

(1) The standard temperature for the determination of specific gravity should be changed to 20° C. A statement of reasons for this change seems to be unnecessary, as the matter has been fully discussed by others, and many chemists have for some time

adopted the custom of making determinations at a temperature not far from that of the average laboratory. If the alcohol tables can be revised in accordance with a standard temperature of 20° C. for specific gravity determinations, a very useful service will be performed, especially in the interest of industrial and food chemists.

(2) The method for glycerol should be made a subject for special study. Experience has shown that it is possible not only to increase the accuracy of the method but to shorten the time of the operation. As the provisional method now stands, it appears to be rather tedious, and there are too many opportunities for error. A large error undoubtedly occurs during the evaporations as well as during the repeated extractions. Also, it appears that the residue weighed as glycerol is far from being pure.

(3) The present methods for determining total, fixed, and volatile acids are exceedingly faulty. The method for volatile acids, especially, fails to give results anywhere near the truth. The difficulty lies not only in the collection of 200 cc distillate but in the operation, which is cumbersome and unreliable. The use of litmus in the titrations of total and fixed acids is open to criticism, as that indicator fails to show all of the acids. A study of the proposed new methods is recommended.

(4) A more comprehensive scheme for the examination of the natural coloring matter of wines is required. Attention is called to the use of standard color charts as a means of obtaining comparable results in the hands of different persons. It is recommended that the association make a special study of the character and properties of the coloring matters existing in genuine wines.

REPORT ON BEER.

By H. E. BARNARD, Associate Referee.

Mr. Barnard, referee on beer, reported that no cooperative work on the subject had been done, and made the following statement in regard to the condition of the methods:

Two years ago I presented beer methods which have since been adopted as provisional. I have been working with those methods since that time and find no special necessity for changing them. For that reason I have not made a special report on beer. Much work, however, seems to be necessary if we must determine the different kinds of beer, and I would only suggest to you the necessity for a careful study of methods of beer analysis with special reference to the adoption of some method which will enable us to tell more accurately than is at present possible whether or not beer is brewed from all malt, or part malt, or from malt substitutes.

REPORT ON DISTILLED LIQUORS: COOPERATIVE TEST OF METHODS FOR THE DETERMINATION OF FUSEL OIL.

By L. M. TOLMAN, Associate Referee.

The cooperative work undertaken this year was a comparison of the present AllenMarquardt method, as given in Bulletin 107, revised, page 98, and a proposed modification worked out by the associate referee and his assistants. The modification was based on the determination of the amount of bichromate reduced in the oxidation of the higher alcohols. This method eliminates the distillation of the acids, which the experiments made have shown are not completely distilled off. In order to test this modified method (for details see paper, p. 206) a series of samples was prepared containing varying amounts of pure amyl alcohol (boiling point 131° C.) in approximately 50 per cent by volume ethyl alcohol, and the samples sent to eighteen different laboratories, asking for a comparison of the modified method with the present method as given in Bulletin 107. Eleven reports were received, and the following table gives

the results, the percentage yields being calculated from the grams of amyl alcohol per 100,000 of 100-proof alcohol, as determined by each method.

Comparison of the Allen- Marquardt method and the proposed modification for the determination of fusel oil, using varying amounts of amyl alcohol.

0.050 gram. 0.100 gram. 0.150 gram. 0.200 gram. 0.250 gram. 0.350 gram.

P.ct.

Philadelphia laboratory.

Portland laboratory

Sunnybrook Distilling Co.. 120.0 125.9

St. Paul laboratory.

Washington laboratory
Galveston laboratory a.

103.0

San Francisco laboratory a.
Seattle laboratory a.

75.6 70.4

Boston laboratory a.

84.40 145.7

119.1

Average.

89.7 117.2 85.7 99.5 85.3

P. ct. P. ct. P. ct. P. ct. P. ct, P. ct. P. ct. P. ct. P. ct. P. ct. P. ct. 99.8 102.0 78.03 111.9 77.74 97.69 100.0 100.0 122.0 78.7 105.0 110.0 130.4 74.1 78.34 62.7 85.69 62.3 82.0 113.0 72.11 86.0 73.8 85.4 78.5 88.06 74.5 87.7 79.7 56.0 106.4 99.70 105.1 80.4 96.6 83.4 95.02 79.4 104.0 76.7 108.8 104.5 100.0 114.9 87.06 108.6 87.86 85.64 80.6 82.64 78.0 83.22 69.06 67.3 134.2 72.1 97.1 62.2 91.5 65.2 86.2 68.3 88.5 68.8 84.6 87.20 87.24 79.28 82. 14] 80.0 79.90 81.36 78.60 72.06 75.52 42.8 63. 1 50.44 74.2 53.74 80.0 50.9 73.22 61.62 66.60 70.16 62.14 61.86 68.19 76.04 124.5 76.36 131.4 121.0 110.3 103.7 77.7 94.7 76.2 91.5 76.7 85.8

85.14

88.3 87.24 87.7

81.68

a Excluded from average.

Some of the results obtained at laboratories which had not had experience in operating the method varied markedly from the other figures and are omitted from the average. The averaged results on the various amounts by both methods are plotted, using as the abscissa of the curves the amount of amyl alcohol used in grams per 100,000 of

PERCENTAGE OF AMYL ALCOHOL FOUND

70

MODIFIED METHOD

proof spirit and as ordinates the average percentage yield.

This curve (fig. 2) shows that the new modification gives uniformly higher results, indicating a regular loss in the old method. This loss is undoubtedly largely

due, as is shown by the experiments, to the failure to drive over all of the volatile acids in the distilling method unless a much larger amount of water is distilled than that. prescribed in the present provisional method. A very much higher yield of acids is obtained by carrying the distillation much further, as is pointed out in the supplementary paper submitted on this subject (p. 206). There is also shown a uniformly increasing loss by both methods as the per cents of amyl alcohol increase. This is doubtless due to the method of extraction, as a 100 per cent yield can be obtained in the oxidation part of the method, as was demonstrated in the experimental work on the determination of the factor 0.001773 (see p. 210). From these results it is evident that a higher yield is due to the more correct estimation of the higher alcohols present in the

FIG. 2.-Graphic of collaborators' results on amyl alcohol by the
Allen-Marquardt method and the proposed modification.

carbon tetrachlorid extract. The curve also shows that the collaborators obtained more uniform results from the new modification than from the method as originally stated. It may be concluded, therefore, that—

(1) The modified method gives higher and more uniform results.

(2) It eliminates a tedious and inaccurate distillation.

(3) It is quicker and gives an opportunity to make check titrations on the same sample.

RECOMMENDATIONS.

As a result of this year's work, including that reported on page 206, it is recommended

(1) That this modification of the Allen-Marquardt method be adopted as a provisional method (see p. 210).

(2) That in the present method a second washing with sodium sulphate be prescribed.

(3) That the method for determining the water-insoluble color be adopted as a provisional method (see p. 207).

(4) That the method for the determination of amyl insoluble color be adopted as provisional (quantitative Marsh test method, p. 206).

(5) That the Roese method given in Bulletin 107, page 97, be dropped as a provisional method on account of the entirely unsatisfactory results obtained with it in the past two or three years.

Mr. Tolman called on Mr. Fischer, of the Bureau of Standards, who spoke in regard to the necessity of unifying the alcohol tables. He called attention to the fact that two tables are now in use by the Treasury Department and a third by the Association of Official Agricultural Chemists. The disadvantages to chemists and practical workers from such a condition of affairs being obvious, it was strongly recommended that the association take some action in the matter. A table based on the calculations of Mendeléeff was recommended by Mr. Fischer. The question of temperature was also discussed, and the whole matter was temporarily referred to Committee C on recommendations of referees, the chairman naming the following members to serve on this committee: Messrs. Tolman, Winton, Hortvet, Bartlett, and Jaffa.

REPORT ON VINEGAR.

By CHARLES H. HICKEY, Associate Referee.

The work which has been done by or reported to the referee deals largely with the lead number for pure cider vinegar and other pure vinegars. The cider vinegars used by the referee were made by the old-fashioned, slow process. The method employed is similar to the one by which Winton and Kreidera analyzed maple products, with some modifications to make it applicable to vinegar. The number of grams of lead precipitated by 100 cc of vinegar is taken as the lead number. Other data are included to make the results more complete. The method as modified by the referee is as follows:

Pipette 25 cc of vinegar into a 100 cc flask; add 5 cc of a standard lead subacetate solution and dilute to 100 cc. Let stand at least one hour, then filter and pipette out 50 cc of the clear filtrate. To this add 10 cc of dilute sulphuric acid and 100 cc of 95 per cent alcohol; let stand over night; filter through a porcelain gooch crucible; wash

a J. Amer. Chem. Soc., 1906, 28: 1204.

with 95 per cent alcohol; dry at a moderate heat for a few minutes, cool and weigh. Calculate the amount of lead in the precipitate (factor 0.6829) and subtract this from the amount in 2.5 cc of the standard solution as determined on a blank test, and divide the remainder by 0.125, thus obtaining the lead number.

The standard lead subacetate used in this work is prepared as follows: Dilute a U. S. P. lead subacetate solution until the specific gravity is 1.25; to one part of this add four parts of water and filter. If the solution becomes cloudy, filter before using, and determine its strength frequently. The referee found that the strength changed but little.

Mr. E. M. Bailey of the agricultural experiment station at New Haven, Conn., has reported work which he did independently on different kinds of samples of vinegar of known purity. He includes other data in his results, especially those on testing a recent method for the determination of malic acid which was formerly applied to maple products. He found that by using this method more malic acid can be recovered than by the old calcium chlorid method. The method for determining the lead number is as follows:

Measure 50 cc of vinegar into a 100 cc flask, add 25 cc of lead subacetate (dilute solution used by Winton and Kreider) make up to the mark and filter. To 10 cc of the filtrate add I cc of concentrated sulphuric acid, 40 cc of water and 100 cc of 95 per cent alcohol. Filter after 12 hours, ignite, and weigh.

The amount of lead in the blank test is determined by diluting 25 cc of the lead subacetate solution to 100 cc; 10 cc are taken out and the lead number determined as in the method just given.

The modified method for malic acid as applied to vinegar is as follows:

To 10 cc of vinegar add an equal volume of water, 3 cc of a 10 per cent solution of calcium acetate, and 180 cc of 95 per cent alcohol. Heat on the steam bath for from 20 to 30 minutes, stirring vigorously at intervals to insure a clear supernatant liquid. Filter on 589 S and S paper, wash with 85 per cent alcohol, and ignite. Dissolve in excess of tenth-normal hydrochloric acid (10 cc) by gentle boiling, and continue to boil for about 10 minutes. Cool and titrate with tenth-normal sodium hydroxid, using methyl orange as indicator.

The results of the work of the referee and those of Mr. Bailey appear in the accompanying table. This shows the variation in the amount of lead precipitated by the different vinegars. In the case of malt vinegar, the results tend to run high; while those of the sirup and distilled vinegar are very low.

It should be noted that in the case of malic acid determinations, which are, of course, not properly such on malt and sirup vinegar, misleading results may be obtained and, in the case of a suspected sample, the malic acid determination would have to be confirmed by the procedure recommended by Leach and Lythgoe.

In comparing the figures for malic acid, phosphates, and the lead number as worked out by Mr. Bailey, it is his opinion that a closer relation exists between the phosphate content and the lead number than between the malic acid value and the lead number. The three highest lead numbers are associated with the three highest total phosphate values; the same is true of the three lowest figures in each case. That this does not follow, however, in the case of lead numbers and malic acid values would seem to indicate that the precipitate produced on adding lead acetate to vinegar is due rathər to the phosphates than to the malates. This is in accordance with the statement of Leach and Lythgoe c that the precipitate produced by lead acetate is not entirely due to malic acid. Tolman and Le Clerc d are also of this opinion.

The other data for pure cider vinegar, included in the table, are fairly typical, and in addition to the old figures the new ones for the lead number are of interest.

a J. Amer. Chem. Soc., 1908, 30: 1285.

bJ. Amer. Chem. Soc., 1904, 26 : 379.
cJ. Amer. Chem. Soc., 1904, 26: 380.

d U. S. Dept. Agr., Bureau of Chemistry, Bul. 99, p. 89.