210 VEGETABLE SUBSTANCES. 



rakes, by which the paste is gathered together and 

 pushed forwards to troughs placed to receive it. In 

 the bottom of these troughs are perforations through 

 which the oil drips, and is conveyed to a division of 

 the cistern set apart for the first produce ; this is con- 

 sidered the best, as having been obtained without 

 pressure, and by the mere breaking of the parts con- 

 taining it. After draining, the paste in the troughs 

 is put into hair bags and subjected to pressure in 

 another part of the mill. The oil thus yielded is 

 considered scarcely inferior to the first, but another 

 separate portion of the cistern is allotted to this 

 second product. After the oil has been pressed out, 

 what is left in the bags is one caky mass, this is 

 taken out, broken, and put into mortars ; the pestles 

 working in these are part of the machinery of the 

 mill, and moved by the same power which actuates 

 the whole. A simple contrivance puts them in or 

 out of action, as occasion may require. The paste is 

 now reduced to a fine meal, and in consequence the 

 oil is freely disengaged from every vesicle. When 

 sufficiently pounded it is conveyed to the chaiiffer- 

 pan, or boiler, where it is heated to a certain tempe- 

 rature. This is not, however, ascertained by a 

 thermometer; recourse is had to a less scientific, 

 though perhaps equally efficient test the heat re- 

 quired to melt bee's-wax is found from experience to 

 be the most beneficial temperature, and this is made 

 the criterion by which the operation is regulated and 

 concluded. The contents of the boiler are constantly 

 stirred with a wooden spatula, to which motion is 

 given by some connection with the moving power of 

 the machinery. 



From the boilers the stuff under process is again 

 put into hair bags, and twice more subjected to 

 pressure ; the oil which comes from the first of these 

 pressings is considered the best of the second quality, 



