(76) 



Soap and Soap Substitutes 



Soap is a compound of an alkali with the acid of a fat or 

 related substance. It is produced by boiling the fat with 

 lye, which causes the fat-acid to separate from the glycerin 

 with which it is combined in the fat. This new compound 

 is soap, and the glycerin is set free. Many resins, being 

 closely related chemically to fats, may be similarly em- 

 ployed, the products being known as resin-soaps. 



Many plants contain the peculiar substance saponin, 

 which foams with water, like soapsuds, and has strong 

 cleansing powers, for which reason they are often employed 

 as soap-substitutes. It is to be noted that saponin is an 

 irritant poison, and that such substances must not be used 

 carelessly nor too freely upon the skin. 



1704. 27 Palm oil. A fixed oil expressed from the seeds of Elaeis guineensis Jacq. 

 (Palmae — Palm Family). Native of western Africa. 



1705. Cochin coconut oil. — (See No. 1620.) Produced in Cochin-China. Used in 



soap-making. 



1706. Crude cotton-seed oil. (See No. 1681.) Used in soap-making. 



1707. Caustic soda. — This is boiled with the fat for the production of the soap. 



1708. Soda ash. Boiled with oil for the production of soap. 



1709. The product of saponification. — The mixture resulting from boiling one of 



the above lyes with fat. 



1710. Graining change. — This sample shows the soap separating from the glycerin 



after the boiling process. 



1711. The finished soap after its separation from the glycerin. 



1712. Treated lye. — The residue after the removal of the soap treated with lye, or 



the recovery of the glycerin and salt. 



171 3. Crude glycerin recovered by the preceding process. 



1714. Dynamite glycerin. — A refined glycerin used in the manufacture of nitro- 



glycerin or dynamite. 



1715. Chemically pure glycerin. — Glycerin in its finally purified condition. 



1716. Common rosin. Used in the manufacture of rosin soaps. 



1717. Rosin change. The product produced by the boiling of lye with rosin. 



1718. Samples of rosin soaps made by the preceding process. 



1719. Tar or pix liquida. Used in the manufacture of tar soap. 



1720. Oil of tar. — A volatile oil distilled from tar. Also used in soap-making. 



1721. Tar soap. Samples of tar soaps. 



1722. Fruta de Jaboncilla, or soapberries. — The fruits of Sapindus divaricata 



Willd. (Sapindaceae— Soapberry Family). Native of southeastern South 

 America. The pericarp of this fruit contains a large quantity of saponin 



^The specimens in this exhibit, numbers 1704-1721, were presented by Colgate 

 & Company, of New York. 



