ASH.

Char a convenient weight of the original sample (from 2 to 5 grams) in a platinum dish, in a muffle, at the lowest possible temperature until free from carbon. If carbon free ash can not be obtained owing to its fusibility, exhaust charred mass with water and proceed as under ash, Bulletin 107, page 38.

CRUDE FAT (ETHER EXTRACT).

Extract a convenient quantity of the product (from 4 to 5 grams) as dried in the determination of moisture with anhydrous, alcohol-free ether, for 24 hours (with fine flour the addition of an equal weight of clean dry sand is frequently necessary). Dry the extract at the temperature of boiling water until it ceases to lose weight.

NOTE.-Iodin numbers should only be obtained upon the ether extract after purification by solution in petrolic ether, but are best made upon the petroleum ether extract. SOLUBLE CARBOHYDRATES (AS DEXTROSE).

Weigh 16 grams of flour into a 500 cc flask. Add 200 cc of water. Shake occasionally during one-half hour. Filter through a dry folded filter. To 50 cc of the filtrate add 5 cc of concentrated hydrochloric acid. Place the flask in water and invert at 70° C. for ten minutes. Cool, neutralize, and bring to 100 cc. Filter. Determine the reducing sugars with Fehling solution, by the official method, as described in Bulletin 107, calculating the reducing sugars as dextrose.

CRUDE FIBER.

Determine the crude fiber in 2 grams of flour by the official method (Bul. 107), filtering through linen in a Büchner funnel.

DETERMINATION OF MOIST GLUTEN.

Dough up 30 grams of flour with 18 cc of water conveniently in an 8-ounce mortar. Weigh off 16 grams of dough equivalent to 10 grams of flour. Place in water at room temperature for one hour and carefully wash out the starch over bolting cloth or a fine horsehair sieve. After expressing all globules of water, weigh the moist gluten upon a watch glass. Dry in a desiccator for 24 hours and complete drying in water oven.

ACIDITY IN FLOUR.

Weigh 18 grams of flour into a 500 cc Erlenmeyer flask and add 200 cc of distilled water, previously freed from carbon dioxid by boiling in tin. Place the loosely stoppered flask in a water bath kept at 40° C. for 10 minutes, shaking repeatedly. Remove the flask and allow it to stand, with occasional shaking, at room temperature for one hour. Filter upon a dry folded filter, rejecting the first 10 cc and receiving the succeeding 100 cc in a graduated flask. Titrate the filtrate with twentieth-normal sodium hydroxid, using carefully neutralized phenolphthalein in alcohol as an indicator. Each cubic centimeter of twentieth-normal sodium hydroxid represents 0.05 per cent of acidity as lactic acid.

NOTE.- Results obtained with flour at temperatures of 15°, 20°, and 25°, respectively, indicate that the acidity in the solution increases with the temperature. The method outlined seems to give the maximum acidity.

TOTAL NITROGEN IN FLOUR.

Determine the total nitrogen in 2 grams of flour according to the official method, preferably the Gunning method, Bulletin 107, page 7. The nitrogen times 6.25 gives total proteids.

GLOBULIN AND albumen (edeSTIN AND LEUCOSIN) AND AMID NITROGEN. Weigh 5 grams of flour into a 500 cc Erlenmeyer flask. Add 250 cc of sodium chlorid solution 1 per cent. Stopper and shake thoroughly. Let stand, with occasional shaking, for three hours. Filter on dry paper. Evaporate 100 cc of the filtrate to small volume in a Kjeldahl digestion flask with 5 cc of sulphuric acid. Add remainder of the

sulphuric acid and determine the nitrogen by the Gunning method. To a second 100 cc of the filtrate add 5 cc of phosphotungstic acid, 20 per cent solution; shake thoroughly, allow to settle, and filter by decantation. Wash slightly with water. Concentrate the filtrate with 5 cc of sulphuric acid in Kjeldahl flask and determine the nitrogen as amid.

Deduct the amid nitrogen from the nitrogen found in the first fraction to obtain the nitrogen as globulin and albumen. This figure times 6.25 gives globulin and albumen.

ALCOHOL SOLUBLE PROTEINS (GLIADIN).

Weigh 4 grams of flour into a 500 cc Erlenmeyer flask, add 200 cc of alcohol 0.90 sp. gr. Shake occasionally during three hours. Let stand 12 hours. Filter through a dried filter. Evaporate the alcohol from 100 cc of the filtrate after the addition of 5 cc of sulphuric acid and determine the nitrogen as alcohol soluble nitrogen. This figure,

less the amid nitrogen, gives the alcohol soluble proteid nitrogen or gliadin.

GLUTENIN (DETERMINATION BY DIFFERENCE).

Deduct from the total nitrogen the salt soluble nitrogen plus the gliadin. This times 6.25 gives the glutenin.

GLIADIN BY POLARIZATION (METHOD OF SNYDER).

Weigh 15.97 grams of flour into a 300 cc flask. Add 100 cc of 0.90 sp. gr. alcohol. Shake at intervals during three hours and let stand overnight. Filter through a dry folded filter. Polarize in a 220 mm tube. Precipitate the proteids in 50 cc of the filtrate with 5 cc of Millon's reagent. Shake, filter, and polarize the filtrate in a 220 mm tube. Add 50 per cent to the reading and deduct the sum from the first reading. This difference times 0.2 gives the per cent of nitrogen as gliadin.

FAT DETERMINATION (BASSETT).

An effort was made to discover a method whereby the time for determining fat and moistures in cereal samples, especially flour, could be much shortened and without a sacrifice of accuracy. H. P. Bassett, of the North Dakota laboratory, was assigned some work along this line, the results of which are embodied in the following:

Fat in flour has been determined usually by the method given by Leach, which is outlined so as to be applicable to all food and feeding stuffs. However, in making fat determinations on flour by Leach's method considerable time is required, and unless special precautions are taken the analyst could never check himself. This, in any method, indicates inaccuracy. In examining the difficulties which might arise to affect this method, it was especially noted that oxidation might take place in drying the flour in a hot-water oven, as is generally practiced, since the fat in the flour is in a fine state of division, which gives the most favorable conditions for oxidation. Again, the special precaution of removing the last trace of moisture from the flour seemed to be an unnecessary point when the ether, as generally employed, contained probably ten times more water than was found in the dried flour.

The extraction by the Leach extractor is also slow, requiring sixteen hours, and in apparatus arranged in such a manner that it can not always be run with safety overnight. This means, then, three full working days before a determination can be madeone for the moisture determination and two for the fat determination.

In order to avoid these difficulties, the following method was developed: Ten grams of flour were weighed into a tared gooch crucible, then placed in the ordinary gooch funnel, which was inserted into a rubber stopper in the top of a low bell-jar, which rested upon a ground-glass plate. Under the bell-jar and directly under the gooch funnel was placed a second glass plate to avoid the possibility of getting vaseline on the bulb, which was to catch the filtrate, vaseline being used to make an air-tight joint between the bell-jar and ground-glass plate. The gooch was now filled with ether six times, each time drawing off with the filter pump. The ether extract was collected in a bulb similar to those with a Soxhlet apparatus. This bulb was then removed and connected with a Liebig's condenser, and the ether distilled off with a 32 candle-power incandescent bulb, this being used as it avoided the possibility of the vapors of ether catching fire, and also has the additional advantage of not being so hot

as to easily burn the fat. The residue in the gooch crucible is now dried in an air oven and weighed, the loss in weight being equal to the fat and moisture. The fat having been determined, the moisture is easily obtained by difference.

The results by this method, however, are considerably higher than by the Leach method-often twice as much-but there is no difficulty in the analyst duplicating his results. Following are some of the figures obtained by this method:

Comparing the results by the two methods, it is noticed at once that none of those by the new method checks those made by the old method, and it was thought at first that there might possibly be an error on account of the moisture present in the flour while extracting, the tests by the old method being carried out on dry flour. A large amount of moisture would probably cause some of the sugar-like substances to be extracted. In order to test this point, the following experiments were performed: Ten grams of flour were weighed out in a gooch crucible as before and placed in a large-mouthed bottle, which was closed with a two-hole rubber stopper. Carbon dioxid which had been dried over concentrated sulphuric acid was conducted through the bottle, the same being arranged in a water bath and heated for four days under these conditions. This was then extracted with ether, according to the new method. The results obtained checked exactly those extracted without drying.

The next point considered was to determine if flour dried in carbon dioxid, under these conditions, would give the same per cent of fat as by the new method or would check the old method. Therefore, 2 grams of flour were weighed out in a small test tube with a hole in the bottom, which was closed by an asbestos plug. This was then placed in the bottle described and dried for four days, after which it was extracted by the Leach method, the following results being obtained:

It is evident that when dried in carbon dioxid the flour does not undergo any oxidation, while from these results the point seems almost, if not completely, proven that it does undergo oxidation when dried in the open air, and for this reason it is hard to obtain results that check.

Numerous determinations have been made by this method and it has given perfect satisfaction as well as being extremely rapid. Time may be saved, as the gooch crucible does not need a new pad every time, the same one being used for at least fifteen determinations by simply knocking out the extracted flour when through. Further, the flask containing the fat may be used six or eight times without cleaning, where a number of determinations are being made.

This work was carried out with ether as the solvent, but chloroform, acetone, or benzin may also be used, similar results being obtained. The following results were obtained:

Fat determinations by the new method, using different solvents.

These results become of value on account of the cost, chloroform and benzin being much cheaper than ether or acetone.

In some cases feed and foodstuffs are not well ground, nor capable of being ground as fine as flour. These of course would not extract by the above method readily, but may be extracted by means of the Soxhlet apparatus instead of the gooch crucible. The Soxhlet apparatus was used on flours and the results check those made with the gooch crucible very closely.

Either one of the solvents named may be used instead of ether, as a larger amount of solvent is required under such conditions, and unless special precautions are taken considerable loss may take place.

Comparison of results on fat, using a gooch and the Soxhlet apparatus.

MOISTURE DETERMINATION.

The moisture, as stated in the preceding method, may also be determined by drying the residue in a hot-water oven and then weighing the crucible and residue, the loss being equal to the weight of the fat and moisture from which the moisture may be determined. The following results were obtained and will be compared with the old method by Leach:

The results here, however, are not so close as in the fat determinations, but out of the numerous determinations that have been carried out in this laboratory the results have checked to within 0.2 to 0.3 per cent, and, in the majority of cases, within a hundredth of a per cent. The following table shows a few results which will give an idea of the accuracy of the method:

Duplicate moisture determinations by new method showing degree of accuracy.

This method has been a means of saving much time, since a large number of such determinations were made during the flour investigation of the past year.

Considerable work was also undertaken in the study of the gluten and protein content of the flour, and a large number of methods were tested. Some results of special interest were secured, but owing to the illness of the assistant having this work in charge only progress in this direction can be reported.

RECOMMENDATION.

It is recommended that for the coming year special attention be given to testing methods for the separation of the gluten constituents of flour, tests being made upon the several grades, as patent, first and second clears, and upon flours produced from different varieties and types of wheat.

REPORT ON VEGETABLES (CANNED PEAS).

By W. L. DUBOIS, Associate Referee.

The work on this subject during the last year has been confined to the examination of canned peas for the purpose of distinguishing soaked peas from those canned when fresh. Such a distinction of course is made with quite a degree of certainty by a