322 THE FLAX CROP. 



small black seeds, which are hard, and have not been 

 broken in the mill. These are often considered by the 

 farmers to be injurious to the cattle; but it does not 

 appear that this opinion is well founded, for they belong 

 to various species of Polygoniim, a genus which is not 

 poisonous. They are objectionable, no doubt, because 

 they are not digestible ; and as they are so small that no 

 difficulty would exist in separating them from the linseed, 

 they are an indication of dirty seed ; and where they are 

 abundant it is not uncommon to find that the proportion 

 of sand also is large. Grass seeds, fragments of flax 

 straw, and of the capsule in which the seed was con- 

 tained, may all occasionally be observed, and when they 

 are abundant, should be noticed. 



As far as possible some judgment should be formed 

 as to the proportion in which these substances are pre- 

 sent; and as grass seeds resist to a considerable extent 

 the crushing process, they may with a little patience 

 be picked out in considerable quantity. Some of the 

 cake should then be reduced to powder, and mixed with 

 cold water, when it ought to form a thick and firm paste ; 

 and if they be used in the proportion of 100 grains of 

 cake to 1 oz. of water, the paste should be so stiff as to 

 retain the form into which it is made. This character 

 is of great importance, because almost every other seed 

 which can be used as an adulterating substance diminishes 

 the stiffness of the paste ; and the only other substances 

 which possess a sufficiently mucilaginous character are oily 

 seeds, which cannot well be mixed with it. The general 

 appearance of the paste, its peculiar odour and colour, are 

 also characteristic. 



Of more strictly chemical tests there are few to be 

 relied upon. One of the best is to mix a small quantity 

 of the paste with a dilute solution of caustic potash. If 

 the fluid acquires a yellow or a green colour something is 



