SUMMARY.

1. A critical study has been made of a method for the determination of tin suggested by Penniman, Baltimore, Md.

2. This method yields results comparable with those obtained by the tentative methods.

3. The new method avoids the objectionable nitric-sulphuric acid digestion, and the hydrogen sulphid precipitation. It requires less time than either of the tentative methods.

ARSENIC.

Some preliminary experiments were conducted in an endeavor to get a satisfactory method for arsenic in gelatin. In view of the unsatisfactory results last year with acid digestion, further attempts along similar lines were abandoned for the present. Instead, attention was devoted to the possibility of adapting the arsenic trichlorid distillation method to gelatin and other products. This work has been interrupted very frequently and not enough has been done to warrant any statement regarding the feasibility of this method.

It is recommended

RECOMMENDATIONS.

(1) That the Penniman method for tin be made the subject of collaborative work during 1918.

(2) That the Gutzeit method as modified during 1916 be made the subject of collaborative work on baking powder materials during 1918. (3) That a study be made of methods for the determination of arsenic in gelatin and similar products.

(4) That a study be made of methods for the determination of zinc, copper, and aluminium in foods.

No report on fruits and fruit products was made by the referee.

REPORT ON CANNED FOODS.

By W. D. BIGELOW (National Canners Association, 1739 H Street, Washington, D. C.), Referee on Canned Vegetables.

No systematic work was done on this subject. The laboratory of the referee gave further attention to tomato products which formed the subject of the last report'. The results are confirmatory of those reported a year ago.

During the last year the referee has given careful consideration to the possible scope of the subject of canned foods in this association

1 J. Assoc. Official Agr. Chemists, 1920, 3: 453.

and has consulted with many others regarding it. As the result of this deliberation, it does not appear that the subject of canned foods lends itself to the work of this association in the same way as many of the other subjects that have been studied. The methods employed for the examination of canned foods are largely the same as are employed for fresh foods and those preserved by other methods. The majority of topics, therefore, that might otherwise come within this field have been classified under other topics in the methods of this association. Those methods which are peculiar to canned foods, such as methods for the examination of the can, the consistency, character, and quality of the product, do not lend themselves to cooperative work and probably are not available for study in the association. If it is the desire of the association, a description of these methods as far as they have been formulated will be presented at a future meeting.

REPORT ON CEREAL PRODUCTS.

By J. A. LECLERC1 (Bureau of Chemistry, Washington, D. C.), Referee. The work outlined by the referee followed closely the 1916 recommendations of Committee C2. In addition to this, the collaborators were asked to make an ash determination, comparing the official method with the calcium acetate method, in which the amount of calcium acetate was reduced to a minimum, i. e., 2.5 mg. per 5 grams of flour.

The moisture determinations were confined to a comparison of the official method of drying in a vacuum water bath with the so-called calcium oxid method, the drying being done, in the latter case, in a vacuum desiccator.

The gluten determinations consisted in comparing the results obtained by using ordinary tap water, distilled water containing 0.1 per cent of sodium chlorid, and distilled water.

The soluble carbohydrates were determined by the Bryan, Given and Straughn method3, and the results compared with those obtained by hydrochloric acid extraction, using 0.5, 1, and 2 per cent hydrochloric acid, respectively.

The cold water extract was studied by comparing the extraction at 10°C. for 45 minutes with extraction at 10°C. for 1 hours and with an extraction at 5°C. for 45 minutes.

The quantitative determination of chlorin was studied by two methods the gasoline extraction method which was used last year, and the extraction in a Johnson fat extractor with alcohol-free ether.

1 Present address, Miner-Hillard Milling Co., Wilkes-Barre, Pa.

J. Assoc. Official Agr. Chemists, 1920, 3: 532.

'Assoc. Official Agr. Chemists, Methods, 1916, 109.

From these results the following conclusions may be drawn:

Moisture. The use of calcium oxid would seem to give results which are as good as those obtained by the official method. In most cases, a slightly larger amount of moisture was obtained by the calcium oxid method than by the official method, which would indicate that the calcium oxid in a vacuum desiccator absorbs practically all of the moisture.

Gluten. The results obtained would seem to indicate that distilled water containing 0.1 per cent of sodium chlorid gives approximately the same amount of gluten as ordinary Washington tap water. On the other hand, the use of distilled water alone causes a very large loss of gluten. Inasmuch as the tap water varies to a very large extent in

different cities, it might be best to recommend that the washing of gluten should be done by the use of distilled water containing a certain proportion of sodium chlorid or other salts.

Soluble carbohydrates.-The results in this case would seem to indicate that the use of 1 per cent hydrochloric acid is to be preferred as a medium of extraction.

Cold water extract.-The results of these analyses would show that a 45 minute extraction at 10°C. gives practically the same results as the 45 minute extraction at 5°C.; 1 hours' extraction at 10°C. gives considerably higher results. Therefore, it might be wise to advocate that the extraction be carried on at a temperature of from 5 to 10°C., instead of limiting it to 10°C. alone.

Chlorin. Three collaborators obtained quite concordant results in the determination of chlorin by the two methods. The results, therefore, are very encouraging, but, inasmuch as these results are so few in number, it is recommended that this work be continued another year. Ash. The results of the ash determination by the use of a minimum amount of calcium acetate are remarkably close to those obtained by the official method. If it is more convenient to use calcium acetate in the determination of ash in flour, it should be allowed in view of these results.

It is recommended

RECOMMENDATION.

That the work of this year be repeated.

No report on wines was made by the referee.

REPORT ON SOFT DRINKS.

By W. W. SKINNER (Bureau of Chemistry, Washington, D. C.), Referee.

The Referee on Soft Drinks, after correspondence with several persons who had signified a desire to participate in work of this character, decided that collaborative work was inadvisable until methods could be suggested with a reasonable prospect of satisfactory results being obtained. The referee is of the opinion that valuable time and energy may be wasted to no purpose in collaborative work on methods which have not as yet been subjected to a critical study and investigation by some one, expert in the particular line of work to which the methods apply. It seems to the referee that if collaborative work is to be maintained on a sound basis, then collaborators should be expected merely to test the application of well-defined methods rather than to assume the role of investigator in the development of new methods.