500 PROCEEDINGS OF THE CHEMICAL DEPARTMENT. 



amount of fibre, which varies from 47 to 10-0 per cent. It is fair 

 to say, however, that in these determinations I have experienced 

 unusual difficulties. The process usually employed for deter- 

 mining fibre in vegetable bodies, and which for most of them, 

 and especially for oil-cake, gives extremely concordant results, 

 fails to some extent with linseed itself; and notwithstanding the 

 most careful work, it was found that in some cases determina- 

 tions made in precisely the same manner varied to the extent of 

 as much as 2 per cent., while in other cases no such difference 

 occurred. I am inclined to think that this difficulty is connected 

 in some way with the large quantity of oil contained in the 

 seeds. The error, however, is not very material, and does not 

 exceed 1 per cent. The mucilage, gum, &c, vary also to a large 

 extent, and are of course largest in those cases in which the other 

 constituents are low ; but there does not seem to be any connec- 

 tion between their proportion and the locality from which the 

 seed has come. 



The composition of the cake obtained from linseed depends of 

 course on two circumstances — first, on the mode of manufacture, 

 and secondly, on the composition of the seed. Under the first 

 head, the variations depend on the quantity of water used for 

 moistening the seed, and the amount of pressure to which it 

 is subjected, in respect to both of which some difference exists. 

 In this country the quantity of water used is such that 

 the cake usually contains from 10 to 14, on the average 

 12 per cent, of moisture, and the occurrence of samples con- 

 taining more or less than this is rare. In America, however, 

 a smaller quantity is generally used, because experience has 

 shown that moist oil-cakes are apt to heat during the voyage 

 across the Atlantic, and to be deteriorated by the change. Hence, 

 when cakes are made in that country for the British market, 

 it is customary either to omit moistening the seed, or to do so to 

 a much smaller extent, so that American oilcakes are often met 

 with containing not more than 7 or 8 per cent, of water, with of 

 course a proportionate increase of all the other constituents. 

 Perfection of the machinery, and the length of time the cake is 

 allowed to remain in the press, have a very important influence 

 on the quantity of the oil remaining in the cake. At present, in 

 this country there is but little difference in the kind of presses 

 used in different oil-mills, the construction of such machinery 

 being in the hands of a comparatively small number of manu- 

 facturers, and the mode of conducting the pressing being similar 

 in most respects. In general, the cake is kept in the press for 

 ten minutes. The flow of oil, at first rapid, has at the end of that 

 time become so slow that it is not generally remunerative to 

 continue it longer. On the other hand, when the demand for 

 oil and cake is large, and the prices high, the manufacturer is 



