Soap-Making Manual Part 21

J. J. VOLLERTSEN, Morris and Co., Chicago, Ill.

[Note A: Resigned.]

Scope, Applicability and Limitations of the Methods.

SCOPE.

These methods are intended to aid in determining the commercial valuation of fats and fatty oils in their purchase and sale, based on the fundamental a.s.sumption commonly recognized in the trade, namely, that the product is true to name and is not adulterated. For methods for determining the ident.i.ty of oils and fats, the absence of adulterants therein and for specific tests used in particular industries, the chemist is referred to standard works on the a.n.a.lysis of fats and oils.

APPLICABILITY.

The methods are applicable in commercial transactions involving fats and fatty oils used in the soap, candle and tanning industries, to edible fats and oils and to fats and fatty oils intended for lubricating and burning purposes. The methods are applicable to the raw oils used in the varnish and paint industry with the exceptions noted under limitations, but special methods have not been included.

LIMITATIONS.

The methods have not been developed with special reference to waxes (beeswax, carnauba wax, wool wax, etc.) although some of them may be found applicable to these substances. The Committee considers the Wijs method superior to the Ha.n.u.s method for the determination of iodine number of linseed oil as well as other oils, although the Ha.n.u.s method has been considered standard for this work for some time and has been adopted by the American Society for Testing Materials and in various specifications. It has been customary to use the Hubl method for the determination of iodine value of tung oil (China wood oil) but the Committee's work indicates that the Wijs method is satisfactory for this determination.

Sampling.

TANK CARS.

1. SAMPLING WHILE LOADING--Sample shall be taken at discharge of pipe where it enters tank car dome. The total sample taken shall be not less than 50 lbs. and shall be a composite of small samples of about 1 pound each, taken at regular intervals during the entire period of loading.

The sample thus obtained is thoroughly mixed and uniform 3-lb. portions placed in air-tight 3-lb. metal containers. At least three such samples shall be put up, one for the buyer, one for the seller, and the third to be sent to a referee chemist in case of dispute. All samples are to be promptly and correctly labeled and sealed.

2. SAMPLING FROM CAR ON TRACK[23]--(_a_) _When contents are solid._[24]

In this case the sample is taken by means of a large tryer measuring about 2 in. across and about 1-1/2 times the depth of the car in length.

Several tryerfuls are taken vertically and obliquely toward the ends of the car until 50 lbs. are acc.u.mulated, when the sample is softened, mixed and handled as under (1). In case the contents of the tank car have a.s.sumed a very hard condition, as in Winter weather, so that it is impossible to insert the tryer, and it becomes necessary to soften the contents of the car by means of the closed steam coil (in nearly all tank cars the closed steam coil leaks) or by means of open steam in order to draw a proper sample, suitable arrangements must be made between buyer and seller for the sampling of the car after it is sufficiently softened, due consideration being given to the possible presence of water in the material in the car as received and also to the possible addition of water during the steaming. The Committee knows of no direct method for sampling a hard-frozen tank car of tallow in a satisfactory manner.

(_b_) _When contents are liquid._ The sample taken is to be a 50-lb.

composite made up of numerous small samples taken from the top, bottom and intermediate points by means of a bottle or metal container with removable stopper or top. This device attached to a suitable pole is lowered to the various desired depths, when the stopper or top is removed and the container allowed to fill. The 50-lb. sample thus obtained is handled as under (1).

In place of the device described above, any sampler capable of taking a sample from the top, bottom, and center, or from a section through car, may be used.

(_c_) _When contents are in semi-solid condition, or when stearine has separated from liquid portions._ In this case, a combination of (_a_) and (_b_) may be used or by agreement of the parties the whole may be melted and procedure (_b_) followed.

BARRELS, TIERCES, CASKS, DRUMS, AND OTHER PACKAGES.

All packages shall be sampled, unless by special agreement the parties arrange to sample a lesser number; but in any case not less than 10 per cent of the total number shall be sampled. The total sample taken shall be at least 20 lbs. in weight for each 100 barrels, or equivalent.

1. BARRELS, TIERCES AND CASKS--(_a_) _When contents are solid._ The small samples shall be taken by a tryer through the bunghole or through a special hole bored in the head or side for the purpose, with a 1-in.

or larger auger. Care should be taken to avoid and eliminate all borings and chips from the sample. The tryer is inserted in such a way as to reach the head of the barrel, tierce, or cask. The large sample is softened, mixed and handled according to TANK CARS (1).

(_b_) _When contents are liquid._ In this case use is made of a gla.s.s tube with constricted lower end. This is inserted slowly and allowed to fill with the liquid, when the upper end is closed and the tube withdrawn, the contents being allowed to drain into the sample container. After the entire sample is taken it is thoroughly mixed and handled according to TANK CARS (1).

(_c_) _When contents are semi-solid._ In this case the tryer or a gla.s.s tube with larger outlet is used, depending on the degree of fluidity.

(_d_) _Very hard materials, such as natural and artificial stearines._ By preference the barrels are stripped and samples obtained by breaking up contents of at least 10 per cent of the packages. This procedure is to be followed also in the case of cakes s.h.i.+pped in sacks. When s.h.i.+pped in the form of small pieces in sacks they can be sampled by grab sampling and quartering. In all cases the final procedure is as outlined under TANK CARS (1).

2. DRUMS--Samples are to be taken as under (1), use being made of the bunghole. The tryer or tube should be sufficiently long to reach to the ends of the drum.

3. OTHER PACKAGES--Tubs, pails and other small packages not mentioned above are to be sampled by tryer or tube (depending on fluidity) as outlined above, the tryer or tube being inserted diagonally whenever possible.

4. MIXED LOTS AND PACKAGES--When lots of tallow or other fats are received in packages of various shapes and sizes, and especially wherein the fat itself is of variable composition, such must be left to the judgment of the sampler. If variable, the contents of each package should be mixed as thoroughly as possible and the amount of the individual samples taken made proportional to the sizes of the packages.

a.n.a.lysis.

SAMPLE.

The sample must be representative and at least three pounds in weight and taken in accordance with the STANDARD METHODS FOR THE SAMPLING OF COMMERCIAL FATS AND OILS. It must be kept in an air-tight container, in a dark, cool place.

Soften the sample if necessary by means of a gentle heat, taking care not to melt it. When sufficiently softened, mix the sample thoroughly by means of a mechanical egg beater or other equally effective mechanical mixer.

MOISTURE AND VOLATILE MATTER.

APPARATUS: _Vacuum Oven_--The Committee Standard Oven.

DESCRIPTION--The Standard F. A. C. Vacuum Oven has been designed with the idea of affording a simple and compact vacuum oven which will give as uniform temperatures as possible on the shelf. As the figure shows, it consists of an iron casting of rectangular sections with hinged front door made tight by means of a gasket and which can be lowered on opening the oven so as to form a shelf on which samples may be rested. The oven contains but one shelf which is heated from above as well as below by means of resistance coils. Several thermometer holes are provided in order to ascertain definitely the temperature at different points on the shelf. In a vacuum oven where the heating is done almost entirely by radiation it is difficult to maintain uniform temperatures at all points, but the F. A. C. oven accomplishes this rather better than most vacuum ovens. Larger ovens containing more than one shelf have been tried by the Committee, but have been found to be lacking in temperature uniformity and means of control. The entire oven is supported by means of a 4-in. standard pipe which screws into the base of the oven and which in turn is supported by being screwed into a blind f.l.a.n.g.e of suitable diameter which rests on the floor or work table.

_Moisture Dish_--A shallow, gla.s.s dish, lipped, beaker form, approximately 6 to 7 cm. diameter and 4 cm. deep, shall be standard.

DETERMINATION--Weigh out 5 grams (= 0.2 g. of the prepared sample) into a moisture dish. Dry to constant weight in _vacuo_ at a uniform temperature, not less than 15 C. nor more than 20 C. above the boiling point of water at the working pressure, which must not exceed 100 mm. of mercury.[25] Constant weight is attained when successive dryings for 1-hr. periods show an additional loss of not more that 0.05 per cent.

Report loss in weight as MOISTURE AND VOLATILE MATTER.[26]

[Ill.u.s.tration: STANDARD VACUUM OVEN]

The vacuum-oven method cannot be considered accurate in the case of fats of the coconut oil group containing free acid and the Committee recommends that it be used only for oils of this group when they contain less than 1 per cent free acid. In the case of oils of this group containing more than 1 per cent free acid, recourse should be had temporarily to the routine control method for moisture and volatile matter[27] until the Committee develops a more satisfactory method.

The air-oven method cannot be considered even approximately accurate in the case of the drying and semi-drying oils and those of the coconut oil group. Therefore, in the case of such oils as cottonseed oil, maize oil (corn oil), soy bean oil, linseed oil, coconut oil, palm kernel oil, etc., the vacuum-oven method should always be used, except in the case of fats of the coconut group containing more than 1 per cent free acid, as noted above.

INSOLUBLE IMPURITIES.

Dissolve the residue from the moisture and volatile matter determination by heating it on a steam bath with 50 cc. of kerosene. Filter the solution through a Gooch crucible properly prepared with asbestos,[28]

wash the insoluble matter five times with 10-cc. portions of hot kerosene, and finally wash the residual kerosene out thoroughly with petroleum ether. Dry the crucible and contents to constant weight, as in the determination of moisture and volatile matter and report results as INSOLUBLE IMPURITIES.

SOLUBLE MINERAL MATTER.