In this connection may be quoted the interesting work of Zelinsky (_Russ. Phys. Chem. Ges. Zeits. Angew. Chem._, 1903, 37). He obtained substances, by acting with carbon dioxide upon magnesia compounds of chlorinated fractions of petroleum, which when decomposed by dilute sulphuric acid, yielded various organic acids. One of these acids on heating with glycerine formed tri-octin, which had the properties of a fat. Dr. Engler, in confirmation of the theory of the animal origin of some petroleums, obtained what might be described as petroleum (for it contained almost all the hydrocarbons present in the natural mineral oil) by distilling animal fats and oils under pressure. _Electrical Production of Soap._--Attempts have been made to produce soap electrically by Messrs. Nodon, Brettonneau and Shee (Eng. Pat. 22,129, 1897), and also by Messrs. Merry and Noble (Eng. Pat. 2,372, 1900). In the former patent, a mixture of soda-lye and fat is agitated by electricity at a temperature of 194 deg.-212 deg. F. (90 deg.-100 deg. C.), while in the latter caustic alkali is electrolytically produced from brine, and deposited on wire-netting in the presence of fat, which is thereby saponified. CHAPTER VI. TREATMENT OF SETTLED SOAP. _Cleansing--Crutching--Liquoring of Soaps--Filling--Neutralising, Colouring and Perfuming--Disinfectant Soaps--Framing--Slabbing--Barring--Open and Close Piling--Drying--Stamping--Cooling._ _Cleansing._--After completion of saponification, and allowing the contents of the pan to settle into the various layers, as described in the preceding chapter, the actual soap, forming the second layer, is now transferred to the frames, this being generally termed "cleansing" the soap. The thin crust or layer at the top of the pan is gently removed, and the soap may be either ladled out and conveyed to the frames, or withdrawn by the aid of a pump from above the nigre through a skimmer (Fig. 1), and pipe, attached by means of a swivel joint (Fig. 2) (which allows the skimmer pipe to be raised or lowered at will by means of a winch, Fig. 3), to a pipe fitted in the side of the pan as fully shown in Fig. 4, or the removal may be performed by gravitation through some mechanical device from the side of the copper. [Illustration: FIG. 1.--Skimmer, with flange for attachment to skimmer-pipe.] Every precaution is taken to avoid the presence of nigre in the soap being cleansed. [Illustration: FIG. 2.--Swivel-joint.]