200 THE COMPLETE GRAZIER. BOOK i. 



The adulteration of seed oil-cakes is unfortunately carried out to such 

 an extent as to render the following remarks of the late Dr. Voelcker, 

 on the testing of them, peculiarly valuable : 



" Let ine point out how you may examine cake, so as to be able to 

 form some opinion as to its qualities. An excellent way of examining 

 all descriptions of cake is to reduce them to powder. I should recom- 

 mend for the purpose a common kitchen grater. You should grate it 

 till you have about half an ounce of powder. It is better to powder it 

 in the way I have mentioned than to reduce it in a mortar to a fine 

 powder, for in that case you would be likely to destroy the character of 

 the seeds of weeds, and reduce the bran, if there is any present, into 

 a condition too fine for examination. The powder should be mixed 

 with about five ounces of water. With good American cake the mixture 

 is transparent, light- coloured; it produces a stiff jelly, which is very 

 agreeable to the smell and the taste. The cake is so nice that one 

 might almost eat it with pleasure. If, however, you examine foreign J 

 cakes, which in nine cases out of ten contain other descriptions of oily 

 seeds besides linseed, you will find the jelly to have a very disagreeable 

 smell, often very much like a canary-bird cage ; it smells like the refuse 

 of canarj'-bird seed. This peculiar smell arises chiefty from the came- 

 lina seed in such cakes. Then I would also observe that the colour is 

 quite different in good, clean, or bad cake. The latter has a dirty grey 

 colour, and if you examine it with a pocket microscope you discover 

 readily the particles that are not linseed. By diluting the thick paste 

 with water and stirring it up, you can recognise the sand, which then 

 subsides better. Then above the sand generally floats the bran, which 

 can be recognised by its structure. Indeed, by the simplest solution, 

 or rather suspension in water, you can recognise a great many foreign 

 matters in cake, and to some extent likewise recognise its condition. 



" Then in addition to this examination, I would observe that in the 

 case of rape- cake you ought to take half an ounce of the powder and 

 mix it with six ounces of cold water, keeping the mixture in a stoppered 

 bottle, and then examine it after the lapse of twenty-four hours not 

 before. It is a singular fact that rape-cake, even when containing a 

 very large proportion of mustard, has no smell whatever, nor is the 

 smell developed immediately on mixing with water. The fact that the 

 smell of mustard does not appear within an hour, or even two or three 

 hours, does not prove the absence of mustard. But if you place the 

 bottle in a tolerably warm room, or even in a common sitting-room, 

 and do not find a strong smell after the lapse of twenty-four hours, 

 you may safely conclude that there is not an injurious quantity of 

 mustard present. If the smell is very strong, more particularly if the 

 taste is strong, mustard is present in injurious quantities. I lay par- 

 ticular stress upon the last remark, if the taste is strong, because all 

 rape- seed is to a certain extent pungent ; indeed all the seeds belonging 

 to the Brassica species develop a strong smell, but you do not get 

 anything like that pungent taste in the specimens I have sent round. 

 It bites you on the tongue, and rape-seed never does that. Of course 



1 This is much less the case now (1892) than twenty years ago. 



