340 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



in the manufaGture of soda ash, and this acid being remarkably cheap is 

 extensively used in the preparation of bleaching powders, and in many 

 manufactories; and thus one discovery ramifies in every direction and tends 

 to the civilization of people in remote countries. In this respect, the manu- 

 facture of soap is a measure of the prosperity of a people. 



I shall leave the practical operations of soap making to gentlemen who 

 are familiar with the subject. 



It is known that when a great number of bodies are buried in trenches 

 under certain conditions, a peculiar change takes place. The olein and 

 glycerine are often removed, and pure acids (stearic and palmitic with 

 ammonia) remain behind. The body retains its natural shape. 



During the removal of the bodies of the victims of the cholera buried in 

 potter's field on Forty-ninth street, numerous examples of this decomposition 

 were observed, and a body is no\v preserved in the museum of the College 

 of Physcians and Surgeons on Twenty-third street. This fat is called adi- 

 pocere, from adeps, fat, and cera, wax. It has been thoroughly investigated 

 by Dr. Wetherill, of Philadelphia. The specimens on the table are from the 

 potter's field, and the soap and candles were prepared from the adipocere 

 in the course of some scientific experiments. 



The Chairman concluded by giving a detailed account of soda ash, illus- 

 trated by diagrams and by specimens taken from each step in the process. 



He then called upon a German chemist, Mr. Engelhard, of St. Xavier Col- 

 lege, to take up another branch of the subject. 



Mr. Engelhard. — Mr. President: The fats and fixed oils, used in the manu- 

 facture of soap, of different qualities and properties, are taken both from 

 the animal and vegetable kingdoms. Chemically pure fats have neither 

 taste, smell nor color, and leave a grease spot on paper. They are lighter 

 than water, having generally a specific gva\yty of .91 to .94. All of them 

 are soluble in ether; a few in alcohol, and none in water. Heated by them- 

 selves they will resist a temperature of 500° Fah., but above that decom- 

 pose; hence their name, fixed oils, in contradistinction to volatile oils, which 

 may be distilled without alteration. 



When oils in vats are heated with the hydrated alkalies, such as lime, 

 potash, soda, a process called saponification takes place*. 



To count up all the different constituents of the known fats and fixed oils 

 would require too much time, and therefore I shall speak of those only 

 which constitute lard, suet, palm oil and olive oil. All fats are mixtures 

 of two, three or four closel}' allied substances, namely, stearine, palmatine, 

 margarine — solid at ordinary temperatures — and one liquid, olein. The 

 more olein a fat contains in proportion to the other constituents, the less 

 solid is it. [The speaker then described in detail the four substances 

 named. They are all composed of carbon, hydrogen and oxygen, in the 

 following proportions: 



Stearine Ciu H,io O^ 



Palmatine Cma H gg O12 



Margarine G^m, ^wi O12 



Olein C„4 Hio4 Oj„J 



If a fat or fixed oil is heated with a caustic hydrated alkali, the following 

 decomposition takes place: 



