COMMENTS OF ANALYSTS.

R. W. Hilts: The methods submitted for this work were adhered to with the exception that in the removal of color from samples 2 and 3 the portions were weighed out into the 50 cc graduated, glass-stoppered flask, acidified as directed, and the piece of fat-free woolen cloth added (about 1.5 inches square). After standing over night the volume was completed with aldehyde-free alcohol, without removing the cloth.

Preliminary tests of the samples were made against a series of standards, but all final determinations were made by matching in the colorimeter. Final comparisons were always arranged so that the depths of tints compared were within 10 per cent, generally less, of equal strength.

Results reported are calculated from averages of four to five readings made in rapid succession with columns of 40 mm and 30 mm, i. e., 8 to 10 readings. Comparisons on the different depths of liquid gave concordant results.

Color in samples 1 (turmeric) and 2 (Naphthol Yellow S) gave no trouble whatever in comparisons. The samples are so highly diluted in the final determination that the color does not interfere. On sample 3 (Naphthol Yellow S) considerably more of the original liquid is present in the comparison tube, due to its lower citral content, and a very slight modification of tint in depths of 40 mm was noticed. With depths of 30 mm there was no apparent difference and tints were matched with ease. Sample 4 (turmeric) behaved similarly to No. 3. In depths of 40 mm there was a slight difference of tint, because nearly 3.5 cc of the original liquid was present in the tube. This slight difficulty disappeared in depths of 30 mm. Samples 2 and 3 were very satisfactorily decolorized by the treatment with the cloth. However, in so far as ease of comparison is concerned this treatment seems superfluous if comparisons are made with comparatively short columns of liquid, as above noted.

A. W. Hansen: The operator could not see that the color interfered with the comparisons.

W. L. Dubois: The comparisons were made in wide Nessler tubes graduated to 100 cc which were cooled to 15° in a large bath and for comparison placed in a tall beaker containing water at 15° and around which was wrapped a piece of white paper, the beaker being set on a white surface and lifted therefrom a few inches at the time of reading. The color in samples 2 and 4 did not seem to interfere with the determinations. The fuchsin sulphite solution when made as directed retained a slightly brownish tint. The fuchsin, however, which we had available for the preparation of this solution was not labeled c. p. and this possibly may have accounted for our failure to get a perfectly colorless solution.

C. L. Cook: None of the readings of any of the samples was interfered with by the presence of the coloring matter used. It was found necessary to allow the fuchsin solution to stand at least forty hours before a blank could be obtained with the aldehydefree alcohol we were able to distil.

F. D. Merrill: Samples 1 and 4 colored with turmeric gave a color differing somewhat from the standard used in the determination of citral. In Nos. 2 and 3 colored with Naphthol Yellow S less difficulty was experienced in matching colors with the standards in the determination of citral when the original extract was used, but when the sample was decolorized by either method suggested it had a very different color as compared with the standard used in citral determination, and great difficulty was experienced in matching colors.

R. S. Hiltner: The small amount of turmeric in samples No. 1 and No. 4 did not interfere perceptibly with the color comparisons.

Sample No. 2, when heated with hydrochloric acid and woolen cloth under reflux condenser as directed, turned brown, apparently due to decomposition of citral. A somewhat similar change took place with No. 3, but to a less degree.

The same result was obtained on these two samples by simply acidifying with hydrochloric acid and treating at once with fuchsin reagent as by allowing the acidified solution to stand over night in contact with wool.

I was unable to secure alcohol that would not respond to the fuchsin test for aldehyde, even after prolonged standing and heating with m-phenylene diamin hydrochlorid.

Besides the figures obtained by the trial method, Mr. Hiltner, of the Denver Food Inspection Laboratory, submitted a set obtained by a method devised by himself using metaphenylene diamin as a substitute for the fuchsin sulphite reagent. The writer makes the following claims for the method:

First. Since there is no color reaction with acetaldehyde, more correct results may be secured in the analysis of commercial extracts.

In the preparation of these extracts, ordinary rectified alcohol is, of course, used. Such alcohol always contains more or less acetaldehyde. Any general reagent for aldehydes, like fuchsin, therefore tends to give too high results for citral because of the reaction on the acetaldehyde present.

Second. It is unnecessary, as stated, to use especially purified alcohol free from aldehydes.

Third. All the operations may be carried on at room temperature.

The following figures were submitted on the official samples: No. 1, 0.251; No. 2, 0.305; No. 3, 0.117; No. 4, 0.061.

Nos. 1 and 2 are somewhat below the average figures submitted by the collaborators. Nos. 3 and 4 are much closer to the actual amount present than those obtained by Mr. Hiltner with the method under trial. As the method was called to the referee's attention only a few days before the meeting, no opportunity was offered to test it this year.

GENERAL DISCUSSION OF RESULTS.

The results obtained on the official samples as a whole exceed greatly the expectations of the referee.

When twelve different analysts are working even with a well-established method under varying conditions, experience has shown that some discordant results are apt to be obtained. When like discrepancies have been obtained with the official methods for nitrogen and potash, it would seem that the results, in the present case, are highly satisfactory.

It appears to be of no advantage to remove the color before making the determinations; in fact, several of the collaborators are of the opinion that it renders the solutions harder to read. The work done at Washington also indicated that there was little advantage to be obtained, certainly not sufficient to offset the loss of citral. The results were slightly better on the alcoholic solutions of citral than upon the extracts. They were better on the terpeneless extract than on the extract containing lemon oil. This is, in all probability, due to the effect of the non-aldehydic constituents upon the color of the fuchsin solution. Where the colors are not of like tint, considerable experience is required in order to correctly match them.

On the final comparisons the standard and sample must contain approximately equal amounts of citral; a deviation of over 10 per cent is not allowable.

The method is not difficult of manipulation, but does require pure reagents, especially in the case of aldehyde-free alcohol. It is highly probable that the greater part of the discordant results are due to the latter. Given a cologne spirit of good quality, there seems, however, to be no reason why good results should not be obtained. It is recommended that the method as submitted for the determination of citral in lemon extracts be adopted provisionally by the association.

REPORT ON SPICES.

By A. L. WINTON, Associate Referee.

The attention of the associate referee was directed to the adulteration of paprika with olive oil, and the methods of detecting this form of adulteration, by papers presented by Doolittle and Ogden and by Loewenstein at the New Haven meeting of the American Chemical Society. Although the time was short for giving this matter suitable attention, a circular letter was sent out on September 5 to such chemists as had previously expressed a willingness to cooperate, and later, samples of two kinds of paprika were distributed, one purporting to be pure, the other adulterated with olive

The methods submitted for study are as follows:

METHODS.

NON-VOLATILE ETHER EXTRACT.

Dry in a desiccator over night or until the moisture is largely removed a sufficient amount of the material to yield an extract of from 0.2 to 0.25 grams. Extract according to the official method for the determination of crude fat (Bul. 107, Rev., p. 39, 5 (b) (1)), collecting the ether solution in a tared flask. Dry the extract at 100° C. for 15-minute periods until constant weight is secured.

IODIN NUMBER.

Determine by the Hanus method (Bul. 107, Rev., pp. 136-7), using the extract obtained as described in the preceding section.

Great care should be exercised in weighing the flask, both before and after extraction, as an error of 1 milligram is equivalent to an error of over 0.5 in the iodin number. A glass-stoppered 200 cc Erlenmeyer flask may be used for the extraction and also, without transfer, for the determination of the iodin number, although in our experience more accurate results may be secured by using a vial-mouth unstoppered flask of about 40 cc capacity, thus reducing the exposed surface to a minimum. In the latter case the flask, after dissolving the extract in chloroform and adding the Hanus solution, is introduced into a saltmouth, glass-stoppered bottle, broken with a glass rod and the titration carried out in this bottle in the usual manner.

It was suggested that in extracting the fat 3 grams of the pure paprika and 2 grams of the paprika adulterated with oil be used, thus securing amounts of extract suitable for determination of iodin number.

ALCOHOL EXTRACT.

Follow the official method (Bul. 107, Rev., p. 163).

DISCUSSION OF RESULTS.

The results obtained by the five analysts who took part in the cooperative work are given in the following table:

Analysis of pure paprika and samples mixed with olive oil.

Genevieve Imus: This collaborator states that through a misunderstanding the portions taken for analysis were weighed out after drying the materials in a desiccator. For this reason the percentages of alcohol extract and nonvolatile ether extract are not comparable with those given by the other analysts and are not given in the table.

C. D. Woods: The ether extract in the determinations made by the method described not being complete, other trials were made, using different quantities of the material and extracting for longer periods. The results are given in the following table:

Analyses of pure paprika and samples adulterated with olive oil, varying weight of sample, and time of extraction (Woods).

Mr. Woods comments on the above results as follows:

I note that Doolittle and Ogden report a much higher iodin number than any of my results would indicate and also that their results are very concordant. With directions as given I fail to see how one could place any reliance on the results of this determination. It may be possible that by running the ether extraction for an exact definite time results can be obtained agreeing reasonably close with each other, but I doubt this somewhat, for it has been our experience that some determinations extract much faster than others, depending on the rate of flow of the ether and the type of extractor used, and that until the extraction is complete there is no surety that two determinations will agree at any given time during the process.

These few determinations seem to indicate that if the iodin number is made on the complete ether extract other material besides fat (resins, etc.) will so increase the weight that the value of the iodin number will be reduced, while, if the determination is made before the extraction is complete, the results can not be depended on to agree. C. S. Brinton comments on his results as follows:

The iodin numbers on the nonvolatile ether of the samples prepared with oil did not agree, and I am reporting only the average of results obtained. I was very much surprised to find the iodin number of the nonvolatile ether extract in the pure sample so much lower by the method you suggest than that obtained by the method used by Doolittle, but this is easily accounted for, because a long extraction with ether carries other material which is not readily soluble in ether and would not be found in the ether extract when a shorter extraction time is used. From the results obtained by this method I do not think that it would be advisable to use an official ether extract for the determination of the iodin number, as by so doing we are liable to overlook samples prepared with olive oil, the presence of which would be revealed by using Doolittle's method.

C. P. Wilson stated that he was not entirely satisfied with the results because with the apparatus he used he found it necessary to dissolve the fat before removing it from the flask in which it was recovered by the extraction.

C. I. Lott: In order to secure evidence with regard to the accuracy of the sampling, analyses were made of three bottles (A, B, and C) of each paprika. The discrepancies in the determination of the iodin number were attributed partly to differences in the amount of extract obtained occasioned by the removal of different amounts of the difficultly soluble resins and partly to errors in the process of determining the iodin number. It was suggested that possibly in the earlier determinations the extract was not completely dissolved in the chloroform preliminary to the Hanus solution. In the later determinations special effort was made to secure a complete solution. With this precaution the following results were obtained: Pure paprika, 116.7, 117.7, 115.1; paprika with olive oil, 116.1, 116.1, 117.6. Further experiments are needed to ascertain whether or not a better agreement of results can be secured by observing special precautions in dissolving the extract.

CONCLUSIONS.

The radical difference in the results reported by the different analysts in the determination of nonvolatile ether extract and the iodin number of the extract may be in part explained by differences in the extraction apparatus employed and in the rate of extraction, some of the analysts securing an extract which contained a much greater amount of resins than that obtained by the others, which resins have a much lower iodin number than the fatty oil. This explanation, however, does not account for many of the differences. For example, Messrs. Woods and Lott obtained practically the same percentages of nonvolatile ether extract in the pure paprika, but one reports an average iodin number of about 80 and the other of about 115. On the other hand, Mr. Wilson obtained the highest percentage of nonvolatile ether extract, and Mr. Brinton the lowest, yet both secured practically the same results on the iodin number. The results reported indicate either that the method of securing the nonvolatile ether extract for the determination of iodin number is seriously at fault, or else special precautions, yet to be determined, are necessary to the success of the process, The results are not only widely discrepant, but they fail to throw any light whatever on the question of adulteration.

RECOMMENDATIONS.

It is suggested that during the ensuing year the following methods be studied: First, extraction on filter paper, with ether, as followed by Doolittle and Ogden, a and, second, shaking for a definite time with a definite volume of ether and evaporation of a portion of the filtered extract. It is believed that satisfactory results can be obtained only by a purely conventional method, using the same weight of material, the same volume of ether, and the same time of extraction. It may be found important, however, to use such portions of the ether solutions as will yield in all cases approximately the same amount of nonvolatile ether extract. The results obtained in the determination of alcohol extract throw no light on the question of added oil.

REPORT ON COLORS.

By H. M. LOOMIS, Associate Referee.

The work of the past year has been chiefly on the identification of colors. For this purpose twelve samples of colored food products were prepared in the laboratory, using the purest colors available, and samples of each were sent to six cooperating chemists. It is only just to state that many of the colors used were not furnished as food colors by the manufacturers. In this work the endeavor has been to prove that the colors used were simple commercial colors, and not mixtures, without special regard to the presence of mineral salts, etc.

J. Amer. Chem. Soc. 1908, 30: 1481.