There are insufficient data at hand on the results obtained with the use of mechanical mixers and samplers to permit drawing conclusions as to the reliability of any of them for products of this kind.

It is respectfully recommended that the work on scratch feeds be continued another year with the idea of securing a uniformly accurate and satisfactory method of mixing and sampling. In this connection some data as to the size of the sample to be used would also be necessary.

PART II.

The second part of the work on feed adulteration consisted of testing a method devised by the referee for the quantitative determination of cottonseed hulls in cottonseed meal. Several years ago two analysts in the Microchemical Laboratory of the Bureau of Chemistry ran a set of twenty-one samples, each making two determinations on each sample, one on coarsely ground meal and the other on the same meal finely ground. The analysts checked themselves and each other so well, and

TABLE 2.

Collaborative results on Sample 2, scratch feed, containing 6 per cent of grit and 8 per cent of weed seeds.

the results agreed so closely with other known data, that the method, although not scientifically accurate, seems to have a decided practical value.

Since it is impossible to simulate under laboratory conditions a commercial cottonseed meal, ordinary commercial samples had to be used for collaborative work instead of meals with known hull content, which would have been preferable. Two samples were used, Sample 1 representing meal manufactured under present milling conditions, with almost no lint left on the seed, and Sample 2 representing meal manufactured under conditions prevailing several years ago, when the seed was not so thoroughly delinted. Unfortunately, Sample 2 being several years old was very rancid, which may have had something to do with its not lending itself readily to a separation of meal and hull by the method under investigation. Samples representing the same type of meal, which were run several years ago while comparatively fresh, did not present this difficulty. For this reason it does not appear justifiable to judge of the merits of the method by the results reported on Sample 2.

In both samples, "A" represents material which was ground until it all passed through a sieve with holes 1 mm. in diameter, and "B" represents the same material ground but not sieved, the major portion thus being coarser than "A".

The directions as sent to the collaborators are as follows:

METHOD FOR DETERMINATION OF HULLS IN COTTONSEED MEAL.

After mixing the sample weigh out 50 grams. Place in a mortar (one which has become smooth seems to be even more satisfactory than a rough one). Add sufficient water to make a thin paste. Let stand about 15 minutes, or more, when it may have thickened, making it necessary to add a little more water before grinding. Grind about 10 minutes. During grinding, as the meal breaks up, it is sometimes necessary to add a little more water. After grinding add sufficient water to carry off easily the finely divided part of the meal by decantation. Stir, and decant into a beaker the yellow mixture which does not settle readily. Continue washing and decanting until the fine portion is washed out. If in any decantation too much hull (brown material) is carried off, return it to the mortar. When the washing seems no longer effective in removing meal without too much hull, repeat the grinding and continue as before until the hulls are practically free from meal. Each analyst may develop slight variations in procedure which seem to him expedient. When this operation is complete and the water is poured off the hulls, spread them out, preferably on a glass plate, and allow them to dry in the air. (Where the atmospheric humidity is high, it may be found preferable to dry the hulls in a drying oven at low temperature. They should be stirred frequently, until they feel quite dry to the touch. They should then be allowed to stand a few minutes before weighing.) When they feel dry to the touch, weigh, and multiply the weight in grams by 2 for the percentage of hulls. This figure represents the minimum percentage of hulls present.

It was recommended that each analyst making analyses of these samples first run a few other samples in order to familiarize himself somewhat with the technique of the method. The referee requested a report as to the number of such preliminary analyses made by the analyst and in only three cases was such a report made. It is therefore assumed that in other cases the analyst was entirely unfamiliar with the method. Several variations in procedure were introduced by different analysts. H. E. Gensler of the Pennsylvania State Department of Agriculture suggests the use of hot water to obtain greater differences in the specific gravity of hull and water. The Barrow-Agee Laboratories suggest that more nearly accurate results could be obtained, and more quickly, if moisture were determined on the meal, then the hulls made moisture-free before weighing, and the moisture calculated back into them on the basis of that originally present in the meal. R. B. Deemer of the Purdue Agricultural Experiment Station introduced the sample into a liter cylinder, stirred it with a mechanical stirrer and decanted at about 15 minute intervals, thus disposing of a large part of the meal, and then made the final separation in the mortar. None of these variations in procedure appears to have a very material effect upon the results. J. H. Roop, also of the Purdue Agricultural Experiment Station, offers the following method:

GRAVITY METHOD WITH CALCIUM CHLORID.

Use a calcium chlorid solution 40 grams to 100 cc. of water, sp. gr. 1.40, sp. gr. of the cottonseed meal 1.39. Sp. gr. of the cottonseed hulls approximately 1.54.

Grind the material in the mortar with a small amount of the calcium chlorid solution, pour the material into a large beaker and add about 200 cc. more of the calcium chlorid solution, stir and allow the hulls to settle, and decant off the calcium chlorid solution. The sample will then be almost entirely freed of cottonseed meal. Grind and treat as before about three times, and transfer the hulls to a linen cloth, washing free from calcium chlorid with hot water, dry at 65°C. and let stand for several hours in air, weigh and calculate the percentage of hulls.

It was suggested by the referee on foods and feeding stuffs that from a chemical standpoint it would be of interest and value to have crude fibers run on the samples. In accordance with this the collaborators were requested to make these analyses if time permitted.

Reference to the table will show that while the collaborators checked themselves and each other satisfactorily, their results were uniformly lower than those obtained by the referee and also lower than the hull content as indicated by the crude fiber figures. In the opinion of the referee this is largely due to the use of a rough mortar, and leads to the addition of the following notes to the directions:

Use a large, smooth mortar. The object is not to grind but to crush the meal. If the mortar is rough, it grinds the hulls too much. Fill the mortar with water before each

E. F. Berger, Agricultural Ex- 23.60 13.46 23.66 | 13.39 9.40

periment Station, E. Lan- 23.76

24.00

sing, Mich.

+ Hulls dried and moisture calculated back on basis of that in original meal. Stirred in a liter cylinder and decanted, then finished in a mortar.

§ Gravity method.

** Hull determination mixture of 1A and 1B.

decantation. Scrape the meal down from the sides of the mortar before each settling. The time necessary for settling will be shorter with each successive decantation. Even the first settling seldom requires more than a minute. Examine the decanted portion for shell by looking at the bottom of the beaker after it has settled. If it is practically free from hulls, it may be discarded. The grinding and decanting may have to be repeated four or five times. Toward the end of the process, when not much meal remains with the hulls, it seems expedient to decant immediately after adding the water to carry off all the remaining meal, even though considerable hull is also carried off. Then remove the hulls which are free from meal from the mortar to the glass plate for drying. After so doing, return the mixture of meal and hulls which was poured off and grind this portion until it is as free from meal as seems practicable, and add these hulls to those previously removed. It must be remembered that the hulls cannot be made absolutely free from meal, but since some hulls are sure to be lost in the decantations, and the hulls are heavier than the meal, those which are thrown away more than compensate for the meal retained.

It is recommended that the work of developing a method for the quantitative determination of cottonseed hulls in cottonseed meal be continued another year.

One of the recommendations carried over from 1914 is that methods for the detection of peat dried at high temperatures in feed stuffs be investigated. It might possibly dispose of this recommendation to say that the referee has never found any difficulty in identifying peat in feeds with the use of the compound microscope, as it retains the sphagnum structure which is very characteristic. It is therefore recommended that this question be dropped.

As to the recommendation made in 1916 that a key or outline for the qualitative detection of adulterants in feeding stuffs be prepared and submitted at the next meeting, your referee reports that such a key has been prepared. Since, however, such enormous changes are taking place in the types of products used for feeds, due to the unsettled world conditions, it was thought better to present this later, when possibly the outline could be made more complete and up to date.

There was no associate referee on organic and inorganic phosphorus in foods and feeding stuffs and no report on this subject was presented.

REPORT ON WATER IN FOODS AND FEEDING STUFFS. By J. O. CLARKE' (State Department of Agriculture, Atlanta, Ga.), Associate Referee.

The work on the determination of water in foods and feeding stuffs consisted in a study of the vacuum desiccator method, using sulphuric acid, lime, and calcium carbide as desiccating reagents in comparison with various heating methods.

1 Present address, U. S. Food and Drug Inspection Station, U. S. Custom House, Savannah, Ga.