PROCEEDINGS OF THE CHEMICAL DEPARTMENT. 491 



It is clear that buyers and sellers of linseed do not attach the 

 amount of importance to the purity of the seed which might he 

 anticipated, but that they must have some other standard of value 

 by which the price is fixed. What this standard may be it is 

 difficult to say, but I am inclined to think they are guided to a 

 great extent by the appearance of the seed. In this respect, very 

 material differences are observable between the samples, the 

 seeds being in some cases much larger, plumper, and brighter 

 looking than in others. The extent to which the seeds differ in 

 weight will be seen from the following table, giving the weight 

 in grains of 1000 seeds of each of the samples examined, to which 

 I have added the number of cubic feet occupied by 1 ton. 



Cubic Feet 

 occupied by 1 ton. 



54-73 



49-97 



51-25 



49-60 



51-65 



53-07 



5041 



51-66 



51-64 



51-40 



51-77 



50-00 



Here, to a certain extent, size of seed appears to have regulated 

 price, for the Messina and fine Bombay, which are among the 

 heaviest, bear also the highest price ; and the Irish and St Peters- 

 burg, which are light, cost less than the others, but the connection 

 is not very close. It may be doubted also whether the standard 

 is a correct one, for the value of linseed to the oil-crusher must 

 mainly depend on the percentage of oil it contains ; and though 

 this varies in different samples, it does so to a very small extent, 

 compared with the differences in price of the seed. Possibly 

 there may be some difference in the quality of the oil obtained 

 from the seed grown in different localities ; but as this is a matter 

 which does not bear upon the particular point into which was 

 the object of my inquiry, it is not necessary for me to consider 

 it more minutely on the present occasion. 



As already stated at the outset, my object was to ascertain the 

 composition of the cake which would be yielded by perfectly 

 pure linseed of different kinds. To do this by freeing the linseed 

 from all impurity, and then pressing it, being manifestly impos- 

 sible, I have proceeded in this way. The seed in its ordinary 

 state, and the pure linseed obtained by picking out the impurities, 

 were separately analysed, and the composition of the cake which 

 it would yield was calculated in accordance with what occurs 

 when the seed is pressed. In performing this operation, the seed 



