either hydrochloric or sulphuric, until an excess is present. The beaker with contents is now transferred to a water-bath and heated until the liberated fatty acids have melted. The contents are now washed into a large test-tube and the whole placed in a refrigerator to cool. The fatty acids collect on the surface and solidify in the form of a cake. The cake, with all traces of fatty matter adhering to the sides of the tube, is transferred to a weighed filter and the whole weighed. The weight of fatty acids divided by the weight of soap-stock taken, gives the percentage of fatty acids in the soapstock. The free or uncombined oil present in the soap-stock remains with the fatty acids liberated from the soap and is weighed with them. This method, while not analytically accurate, suffices for technical purposes.

Determination of Free or Uncombined Oil in Soap-stock.About 10 grams of the sample, more or less, according to the amount of moisture present, are weighed out into an Erlenmeyer flask and dried. When the sample is sufficiently dry, the flask is cooled and a quantity of petroleum-ether (of a quality that leaves no residue on evaporation), sufficient for extraction, is added. A return-flow condenser is inserted in the mouth of the Erlenmeyer flask and the whole transferred to a water-bath and heated until extraction is complete. The extract is then separated from solid matter by filtering through filter-paper, with repeated washing with petroleumether to insure complete separation of the oil, into a weighed beaker. The filtrate is evaporated to dryness on the water-bath and the residue weighed. This weight divided by the weight of the sample gives the percentage of free, or uncombined oil.

Determination of Total Fatty Acids in Soap-stock.-To ascertain the percentage of fatty acids from both soap and oil, it is necessary to complete the saponification of the oil in the sample with alcoholic potash solution. To the weighed sample in an Erlenmeyer flask, alcoholic potash solution is added in quantity sufficient to complete the saponification of the free oil; a return-flow condenser is inserted in the mouth of the flask and the whole heated, with occasional stirring, until the soap formed is dissolved. The condenser is then removed and alcohol expelled by boiling. The total fatty acids are now set free, and washed and weighed as previously described.

CHAPTER VIII.

COTTONSEED PRODUCTS (Continued).

Cottonseed-oil Cake. Classification. Trimming Cottonseed-oil Cake. Cottonseed-meal. Cake and Meal and its Proper Handling. Yield of Cake and Meal. Classification. Composition. Quality and Grading of Cottonseed-meal. Uses. Determination of Oil in Cottonseed-oil Cake. Cottonseed-hulls. Uses. Cottonseed-hull Ashes.

Cottonseed-oil Cake.-On the release of pressure and the descent of the ram of the hydraulic press, the cakes, still retaining the heat imparted during cooking, are ready for removal. They are transferred quickly to the "stripping-table," where "strippers" separate the press-cloths, which are handed at once to the attendants at the cake-former for use again. The hot cakes, firm as a board, are loaded upon trucks and taken to the storage-room, where they are allowed to remain until cold. A record of the approximate weight. of seed crushed may be kept by multiplying the weight of cake by two, to which sum is added the weight of oil expressed.

The appearance of the cake indicates the thoroughness of cooking and the degree of moisture left in the cake. Insufficient cooking, leaving thereby an excess of moisture in the meats, causes the cake to "creep" in the press. This condition may also be caused by too rapid travel of the ram during the application of low pressure to the press. Ends of the cake should be soft. They carry upwards of 30 per cent. of oil, which is recovered in trimming. Hard ends are the result of "creeping," and cause interior portions of the cake to retain much oil. Thorough cooking, the formation of a cake of uniform density and thickness, the wrapping of the same in presscloth so that no unevenness is produced, and the proper application of low and high pressure, produce a cake from which the press-cloth is easily separated and which contains, after recovery of oil from the trimmed ends, the minimum percentage of residual oil.

Classification. According to the rules governing transactions in cottonseed products, cottonseed-oil cake is graded and classed as follows:

Choice cake must be bright yellow in color, sweet in odor, soft and friable in texture, not burnt in cooking, free from excess of hulls, and must produce, when properly ground, a bright meal of deep-canary color.

Prime cake must be of good color, yellowish, not brown or reddish, sweet in odor, firm but not flinty in texture, free from excess of hulls, and must produce, when properly ground, a prime meal.

Off cake comprises all grades of cottonseed-cake which are distinctly off in color, taste, or odor, or which have been improperly manufactured, so as to incorporate in it a very large percentage of lint and hulls, or to produce an exceedingly hard, flinty texture.

Cottonseed-cake, unless otherwise specified, shall be packed in good, strong, sound Dundee bags, either new or second-hand, at the option of the seller, unless specified in contract. Packages must be well sewed and in good shipping order and bear a shipping-mark or a brand.

Trimming Cottonseed-oil Cake.-The soft ends of the cake contain over twice as much oil as the body of the cake. Inasmuch as the value of cottonseed-meal for feeding purposes lies primarily in the protein content and not in the oil, the value of the cake is not deteriorated by its removal. The recovery of the excessive percentage of oil from this portion of the cake conduces to efficiency of operation by increasing the yield of oil, and as its removal proportionately increases the percentage of protein in the cake remaining, the value of the cake is improved rather than otherwise. A form of automatic cake-trimmer adapted for use in cottonseed-oil mills is shown in Fig. 54.

The trimmer has a capacity of 21 cakes per minute. The cakes are piled on the feed-table of the machine, shown empty in Fig. 54, and are automatically trimmed, one at a time, and automatically repiled on the receiving-table, shown partly filled. As the stripper is expected to pile the cake on the machine, the requirements for extra labor practically disappear. The cakes are trimmed by passing between two cutters on opposite sides of the machine, which

are free to separate as required by the individual cake passing between them. These cutters are held against the cake by tension weights, which may be increased or diminished according to the closeness of trimming required. As the cake passes between them the resistance due to its hardness spreads the cutters, which thus remove the softer portions of the cake, leaving the hard undisturbed. In this way each individual cake is trimmed, irrespective of its length, shape of its ends, or the amount of oil carried by it.

The receiving-table lowers itself automatically by the thickness. of each cake as it is delivered by the trimmer. Thirty to forty cakes may be piled upon it before it is necessary to remove them and to raise the table to its former position. The table is mounted on the upper end of a vertical plunger, working in a hydraulic cylinder extending through the floor, and is raised by water or oil pressure taken from piping carrying pressures from 40 to 4000 pounds per square inch.

The meal removed from the cake, which is very fine, passes. through openings in the feed-table and may be returned directly to the kettle by spouting and conveyors. Each trimmer with receiving-table requires a floor space of about 6'.8×5'.3. Two or three horse-power is the estimated requirement for the machine.

The abraded ends of the cake are worked over with fresh meats in the cooker. As they are considerably dryer the addition of more or less water is required for their proper reduction. The proportion of cake-ends and meats must be determined by the judgment of the cook.

Cottonseed-meal.—When ready for reduction, the cool and dry cakes are fed into a cake-breaker, a form of which is shown in Figs. 55 and 56. The cake is discharged from the breaker in small fragments, which are fed directly into the mill (Fig. 57). In mills of this type, which mark a great improvement over the old buhrmill, reduction to powder or meal is effected by attrition. An attrition mill consists essentially of two upright reducing discs or plates, both of which revolve, one in opposite direction from the other. The material to be reduced is fed regularly from a hopper on top of the mill into the centre or eye of one of the discs and is thrown back and forth against the surfaces. The particles of cake, treated