188 PROCEEDINGS OF THE CHEMICAL DEPARTMENT. 



farmer who judges by the eye and the palate, has only to 

 deceive these organs ; while, if he deals with the more cautious 

 individual who looks at the analysis, he has to solve the some- 

 what more difficult problem of concocting a mixture which shall 

 resemble the genuine article, not only in taste and appearance, 

 but in composition also. In the former case the number of sub- 

 stances which can be used for adulteration is pretty large ; in 

 the latter it is more restricted, and, in general, it is necessary to 

 use them more cautiously, and for the most part in smaller 

 quantity. 



It is scarcely necessary to observe that the substances used 

 for adulterating oil-cake must be of vegetable origin, and those 

 are selected which can be most easily mixed with linseed, with- 

 out provoking suspicion, and are at the same time materially 

 lower in price. Bran, rice-dust, rape, and a variety of similar 

 substances are used for the purpose. In fact, the number of 

 materials which can be employed is very large, and the selection 

 is greatly influenced by local circumstances. The existence near 

 the soil crusher's premises of a work furnishing a suitable refuse 

 which can be introduced into the oil-mill without exciting sus- 

 picion will often determine its use ; and thus it happens that 

 the materials employed are constantly changing, and it is often 

 difficult, if not impossible, to identify them when they are 

 ground up in the cake, though it may be easy to say that they 

 are not linseed. 



The adulterations of oil cake are of two kinds — 1st, Those 

 which seek to imitate the real cake both in appearance and com- 

 position. 2nd, Those in which so large a quantity of inferior 

 material is added, that the composition of the cake is materially 

 altered. 



The first is necessarily by far the most dangerous kind of 

 adulteration, and that most likely to escape detection. It 

 admits of being carried out with comparative ease, in conse- 

 quence of the considerable variation in the composition of 

 genuine linseed cake, which appears to be due to differences in 

 the quality of the seed. In some instances the seed is small 

 and shrivelled, and the husk bears a large proportion to the 

 kernel, in others it is large and plump, and then the proportion 

 of husk is small ; and when the latter seed is crushed, it gives 

 a cake much richer in albuminous compounds than the former. 

 [t is not easy to say to what this difference in the quality of the 

 seed is due, but I think I have observed a decided superiority 

 in that grown in warm climates. Whatever may be the cause 

 of the difference, there is no doubt about its effect on the com- 

 position of the cake, as may be seen from the subjoined analyses 

 of two samples, both of which were ascertained by careful ami 

 minute examination to be made from pure linseed, without 

 foreign admixture — 



