Proceedings of the Polytechnic Association. 875 



of tlie seed of an African palm. It has tlie consistence and something 

 of the color of butter, and is used in this country for making palm 

 oil soap. The process of making the oil differs from that of making 

 olive oil. The pulp stripped from the seed stones, has boiling water 

 poured upon it, whereupon the oil floats and is skimmed off. A sub- 

 stance called palmitic acid is derived from it, and used in 1;he manu- 

 facture of candles. Cocoa nut oil is largely made in Ceylon. The 

 kernel is ground in mills and pressed, the ground material is called 

 coppcrah. Linseed oil is made by grinding the seed and subjecting 

 it to great hydraulic pressure. It is a good drying oil, as it is easily 

 oxydized. It may be evaporated to a gummy consistence, and vul- 

 canized as a substitute for india-rubber. Castor oil is made with or 

 without heat, from the beans of the Palma Christi plant. It is used 

 in India for burning. Poppy seed oil is produced very largely in 

 France; a white poppy is grown exclusively for the purpose. It is 

 esteemed as an excellent substitute for olive oil. Almond oil is 

 expressed from the kernels of the nuts, and forms a very bland and 

 valuable oil. , One hundred weight of almond kernels are required for 

 fifty pounds of oil ; but with the bitter almonds an essential oil may 

 be expressed from the marc or residue. A very curious substance is 

 the product of the Chinese tallow tree. It is extracted from the 

 seeds by placing them in boiling water. It is white and harder than 

 common tallow. Yegetable oils when used on leather are deleterious 

 to the strength and durability of the material. 



Dr. Yanderweyde said he was much in faver of the castor bean 

 as a lubricant. Much difference exists in the nature of the various 

 vegetable oils. His experience with castor oil on leather was very 

 favoral^le, and he proposed to test the utility of this oil still furtlier 

 by using it on one boot and fish oil on the other. He would report the 



result at a future meeting. 



Adiourned. 



November 11, 1869. 



Professor S. D. Tillman in tlie chair; C. E. Emery, Esq., Secretary. 

 The following notes on science were presented by the chairman : 



A Tkst for Coloks. 

 M. Nickles has found that fluoride of potassium will discharge a 

 Prussian blue color, and not affect the indigo and aniline colors. This 



