125 



OILS AND FATS. 



BLEACHING AND CONCENTRATION OP VEGETABLE OILS. 



Hitherto the bleaching of oils has been obtained by the " natural method," 

 the oils being exposed in large metallic receivers for a certain lapse of time, 

 usually several Aveeks, to the action of the open air and the light of the 

 sun, or else by combining, for the purpose of accelerating the process, in special 

 apparatus, the action of the air <>n the oil causing the heated oil to fall in 

 drops in the form of rain in a dry or heated counter-current of air, the air 

 being admitted into the heated oil in the lower part of receivers by means of 

 steam, and then shaking the oil. However, in these two arrangements the 

 bleaching of the oil is insufficient as compared with the time required. The 

 apparatus also does not alloAV of obtaining high degrees of concentration with- 

 out the addition of drying substances, like those employed for varnishes, in the 

 preparation of printing and lithographic ink, or for the production of linoleum 

 and other similar articles. M. Lewyak has established an apparatus capable of 

 concentrating the oil to any degree of density desired without the addition of 

 drying substances. This result is obtained in a double walled boiler capable of being 

 closed hermetically ; the oil is heated by means of steam, while the air is heated in 

 the apparatus and introduced through the oil from the bottom to the top in bubbles 

 or thin jets ; the oil is kept in movement by means of an agitator constructed 

 principally for securing an intimate mixture. 



The kettle which serves for boiling the oil is mounted on a cast-iron frame, 

 but may be established on a different foundation. The kettle is closed hermetically 

 by a cover which is furnished eccentrically with au air tube and concentrically with 

 an opening for the shaft of the agitator. The kettle is furnished with a bottom of 

 special construction. This is provided centrally with a passage for the air tube, 

 which is rendered tight by a collar ; on its periphery is a discharge tube, for cases 

 where the oil remains liquid after treatment. The kettle has two walls ; in the 

 space formed by these walls the return steam which heats the kettle is made to 

 enter. The hollow space is furnished with a steel index tube and a discharge tube for 

 the condensing water. The air tube, which penetrates into the space mentioned 

 above and which surrounds the kettle several times in the form of a worm, comes 

 out below and afterwards penetrates into the kettle only at the bottom. It is 

 evident that all the tubular connections on the inside of the said space must be 

 strong, because the space is heated by steam at about 100 deg. C, and they must 

 support an inside pressure of air of from 2 to i atmospheres. On the bottom of the 

 kettle the central support is arranged. This rests on several strips of metal arrayed 

 in a half circle, crossing each other and connected together at the upper part. In a 

 socket turns the extremity of the shaft, worked by a bevel wheel, arranged on a 

 motor shaft. On the shaft are fixed three groups of paddles furnished with holes. 

 Each group is composed of four paddles, arranged crosswise at right angles to each 

 other and worked toward the light. A bevel toothed Avheel is connected also with a 

 second bevel toothed wheel, which slides on a tube, so that this turns in the direction 

 opposite the shaft worked by another toothed wheel. 



On the tube four arms are fixed at right angles to each other. The extre- 

 mities of these arms are furnished with a flat piece of iron. These irons extend along 

 the walls of the kettle to the bottom, and on these walls are arranged paddles, which 

 are similar to those of the motive shaft and also perforated ; these paddles occupy 

 the place, between the other paddies and the bottom. The paddles arranged, some 

 opposite to the others, are connected in the middle in snch a way that these coanec- 



