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 Hanus method for the determination of iodine number of linseed oil as well as other oils, although the Hanus 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 Hübl 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 accumulated, when the sample is softened, mixed and handled as under (1). In case the contents of the tank car have assumed 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.