(101) 
Resins, being much like fats in their chemical nature, 
may ic substituted for a fats, resulting in what are 
known as “resin soaps.” In this case may be seen a 
series of products which illustrate the various steps in the 
soap-making process. 
Many plants, such as soap-root and soap-bark, contain a 
peculiar substance called “‘saponin,”’ which possesses the 
property of forming a lather with water, like soap. Al- 
though this is too irritating for general use upon the skin, 
it has great cleansing power and is largely employed as a 
soap substitute in the cleansing of fabrics, the removal of 
grease and for similar purposes. Many vegetable sub- 
stances containing saponin are displayed in this case. 
Volatile or Essential Oils. Cases 55-60.—These pro- 
ducts are exceedingly numerous in the vegetable kingdom, 
being responsible for the fragrance of flowers and other 
parts of the plant, as well as for some odors which are ex- 
ceedingly disagreeable to man. The volatile oils are 
stored in special cells or cavities and are extracted for 
human use in various ways, the most usual being that of 
distillation. This method consists in tightly packing the 
plant or plant part containing the oil, in a still, flooding 
with water and applying heat. A small quantity of the 
oil thus driven out of the plant-tissue is absorbed by the 
water. After the water has become saturated with the 
oil, the remainder of the latter passes off in the form of 
vapor, which is caught and condensed by cooling. In a 
few cases, as those of lemon and orange-peel oils, the oil 
is extracted by pressure. Volatile oils are usually rather 
expensive products, some of them, like attar of roses, posses- 
sing a very high money value. The following are some 
of the best known volatile oils. From roots are obtained 
the oils of lovage, elecampane, and muskroot; rootstocks or 
underground stems furnish the oils of calamus, ginger, 
orris-root, and wild ginger; herbage is the source of the 
oils of pennyroyal, tansy, spearmint, and peppermint; 
wood furnishes the material to make the oils of red-cedar 
