RAPE 



RAPE 



533 



Manufacture of oil. 



There are or have been several ways of crushing 

 the seed for oil, and many machines have been con- 

 structed for each process. The early method was 

 by use of a stamping mill in which the seed was 

 run into mortars and crushed by means of stamp- 

 ers. This was a cumbersome process and gave way 

 to the roller system, in which the seeds were run 

 between rolls set at proper distances. The early 

 system of rolling did not crush the seed fine enough 

 and it was necessary to recrush by means of mill- 

 stones or runners. This method also proved too 

 costly and cumbersome, and was replaced by a 

 machine in which were three sets of rollers. Each 

 set was a little closer than the preceding, and the 

 crushed seed passed from one to the other until, 

 after passing the third set of rolls, it was in proper 

 condition to go into the presses. 



It was found later that the extraction of the oil 

 was facilitated by heating the crushed seed before 

 putting it into the presses. Enough of the pulp 

 was placed in a shallow pan to make one cake — nine 

 to eleven pounds. These pans were exposed to heat 

 varying from 167° Pahr. to 176° Fahr., but never 

 to 212° Pahr., as this would have damaged the oil. 

 In the modern process of heating, the pulp is 

 steamed to the required temperature. 



Many styles of presses have been used, but all 

 the more modern presses are operated by hydraulic 

 power and are composed of several pans so ar- 

 ranged that pressure can be applied all at once. 

 Experience has shown that a more thorough ex- 

 pression of the oil can be made when cakes are in 

 separate pans than when several cakes are placed 

 one on another in the same press with only the 

 cloths between. The material for each cake is 

 placed in a cloth so cut that the ends when folded 

 overlap, making a perfect case. The cloths are 

 composed of linen on one side and wool on the 

 other, with ropes sewn between the two at inter- 

 vals, thus giving the scalloped appearance to the 

 cakes. The cakes are submitted to a pressure of 

 2,840 pounds to the square inch and the process of 

 oil expression requires fifteen minutes. After the 

 pressure is removed, the cakes are taken from the 

 press and the edges trimmed on the assumption that 

 the oil has been completely removed at the center 

 of the cake, but has not from the edges. The 

 material cut from the edges is mixed with a new 

 lot and repressed. 



The oil runs into a collecting reservoir from 

 which it is pumped into a 2,000- gallon tank. Prom 

 here the crude oil is pumped either into barrels for 

 crude oil use or into refining reservoirs. In refining 

 the oil it is exposed first to a heat of 86° Pahr., in 

 an open vat to which | per cent to 1 per cent of 

 sulfuric acid is added with continuous stirring. In 

 stirring, a vertical movement is preferable to a 

 horizontal or rotary motion. Prom the heating vat 

 the oil is run into a tank and washed several times 

 with hot water, and then into a vat where 5 per 

 cent of common salt is added and the oil left until, 

 with the aid of the salt, it has become completely 

 clarified. Por the purest oils, suitable for table use, 

 a filtrating process is resorted to in which the oil 



is run through successive layers of linen tow and 

 moss. 



Refined oil should be of a pale yellow color, 

 clear, free from acid and without any rancidity. It 

 should burn with a clear white light without soot 

 or odor. Such oils are used for lights and, when 

 specially treated, for table and cooking purposes. 



Lubricating oil should contain as much fat as 

 possible, be clear from acid and mucus and form no 

 sediment. Such is the crude rape-seed oil, and this 

 is its principal use. 



By-products. 



Rape-seed cake is a valuable by-product of rape- 

 oil manufacture. The cake is broken by means of 

 mills made for the purpose, where the cake passes 

 between toothed steel cylinders. After breaking it 

 may be ground into a fine meal in roller mills. This 

 meal contains 9.23 per cent of oil and 5 per cent 

 of nitrogen, which makes it a valuable feed, when 

 it does not become rancid, and a valuable fertilizer 

 at all times. It has been found that 85 per cent of 

 the protein substances, 88 per cent of the fat sub- 

 stances, and 78 per cent of the non-nitrogenous 

 substances in rape meal are digestible. While a 

 valuable feed, rape-seed meal needs to be used in 

 conjunction with other feeds, for when used exclu- 

 sively it forms flesh of a soft and flabby and wholly 

 undesirable character. 



The high percentage of nitrogen contained in the 

 meal and the amount of phosphoric acid in the ash 

 make rape-seed' meal a very valuable fertilizer. 

 Analyses have shown 6.82 per cent of the meal to 

 be ash, and of the ash 32.7 per cent is phosphoric 

 acid. Besides these two valuable soil constituents, 

 the meal leaves a residue of organic matter to im- 

 prove the mechanical and water-holding properties 

 of the soil. The 5 per cent of nitrogen contained in 

 the rape cake is almost immediately available. In 

 their experiments at Rothamsted, England, Lawes 

 and Gilbert found that 70.9 per cent of the nitro- 

 gen in the rape-seed meal was utilized by the crop 

 the season of application. In this it compared very 

 favorably with nitrate of soda, of which 78.1 per 

 cent was found to be immediately available. 



Value. 



Grisdale, of the Ottawa Experimental Parm, esti- 

 mates the cost of growing an acre of rape at 

 six dollars- and ninety-five cents. The cost will, of 

 course, vary with the locality, price of labor, and 

 other factors. "When care is taken, crops of 1,000 

 pounds of seed per acre are not uncommon. If sold 

 at five cents per pound, the seed would bring fifty 

 dollars per acre. Estimating the growing of the 

 crop to cost ten dollars per acre, the rape would 

 still give a net return of forty dollars per acre. 

 This would surpass a crop of ninety bushels of oats 

 per acre, taking into consideration the straw and 

 the heavier soil-feeding of the rape. Rape may 

 therefore prove a paying crop in some sections. 



Literature. 



Thomas Shaw, Porage Crops, Orange Judd Com- 

 pany, New York ; John Wrightson, Fallow and 



