IGO OILS AND FATS. [VI. 



chouc to 50 pts. rape-oil, and heat until the mixture is com- 

 plete. A very unctuous oil is thus formed, which remains fluid 

 at freezing temperature, and does not clog the machines, but 

 facilitates the motion of their parts. 



Fat Oils, to distinguish them. — Heydenreich proposes 

 (Journ. de Connais. Utiles, 1849) to distinguish these oils from 

 each other by their odor when warmed, their color by contact 

 with oil of vitriol, and their specific gravities. By the first 

 process, the oil is heated in a porcelain capsule over a spirit- 

 lamp, when the peculiar volatile odor of fish, linseed, and other 

 oils may be detected, especially if compared in the same way 

 with the unadulterated oils. For the acid test, 10-15 drops 

 of the oil are dropped upon a piece of glass, underlaid by 

 white paper, and a drop of oil of vitriol is brought in contact 

 with it by a glass rod. If it be rape-oil, a greenish-blue 

 circle is formed around and at a short distance from the drop, 

 while light yellowish-brown striae form towards the centre. 

 The same takes place with oil of black mustard, but 25-30 

 drops of the oil are required. With whale oil, the color is 

 reddish, after 12-15 minutes violet on the edge, and in 2 

 hours violet throughout. Olive oil gives a pale-yellow passing 

 into greenish-yellow. Linseed oil is at first dark reddish- 

 brown and then black. 



2. Chandlery. — The more solid fat, stearin, is separated 

 from the more fluid olein by pressure, to make stearin-candles, 

 or, the fats being decomposed, the more solid stearic acid is 

 separated from buttery or fluid acids, to make stearic acid 

 lights. Under this head we may embrace spermaceti and 

 wax. There is but little novelty off"ered on any of these 

 points. 



Stearin, ^c. — To separate the solid from the more fluid fat 

 in palm oil, lard, &c., the fats are granulated and pressed cold 

 in bags by a powerful hydraulic press, the olein which flows 

 out being used for soap. The contents of the bags being 

 again granulated, and pressed between warm plates of iron, 

 the balance of the olein with some margarin and stearin is 

 removed. To remove color from the stearin thus obtained, it 



