FOOD 257 



If water be added to a paste formed of the grated cake, it 

 is possible to detect the bran and sand, the former floats, 

 the latter sinks. It is stated that the determination of the 

 amount of sand is valuable, as a definite figure may be 

 assigned to it ; in pure cakes it should not exceed 2 per 

 cent., or even less, if the seed has been properly screened. 



There is no starch in linseed cake, but when rice, oats, 

 and other cereals are added, the starch may be extracted 

 by the above process, and readily tested for with iodine. 



The examination of rape cake is principally made for 

 mustard, but this should also be looked for in linseed cake. 

 Voelcker recommends half an ounce of the grated cake 

 being mixed with six ounces of water, placed in a stoppered 

 bottle kept in a warm room, and examined after twenty- 

 four hours ; even when rape cake contains a considerable 

 amount of mustard, no smell of the same is developed for 

 some time. The explanation of this is that mustard seed 

 does not contain mustard as we recognise it, but possesses 

 two substances, which produce mustard, one is a ferment 

 known as ' myron,' which acts upon the second body 

 ' myronic acid ' under the influence of moisture, and pro- 

 duces oil of mustard. 



If mustard seeds be treated with boiling water the 

 ferment is destroyed, and no mustard oil formed. So 

 marked is this that even pure mustard cake may be 

 rendered harmless in this way. 



The practical application of this fact is evident, rape 

 cake can be safely employed when steamed or treated with 

 boiling water after being reduced to a coarse powder, and 

 under this process not only loses its acrid qualities, but 

 acquires a smell and taste which induce cattle to eat it 

 readily. As rape is half the price of linseed cake the value 

 of this method is evident. 



Voelcker* urges that a linseed cake guarantee should 



make no reference to the usual 95 per cent, pure seed, as it 



leaves out of account the remaining 5 per cent, which may 



be poisonous. Further he says the cake must be sold as 



* Journal Boyal Agricultural Society, vol. Ixiii., 1892. 



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