PROCEEDINGS OF THE CHEMICAL DEPARTMENT. 495 



The low percentage of nitrogen in this mixture necessarily 

 produces a marked effect on the cake in which it is contained. 

 The small proportion of oleaginous seeds contained among the 

 impurities, as indicated by the proportion of oil, is also to be 

 noticed. It may be well also for me to explain, that this does 

 not affect the quantity of oil found in the cake. The fact is, that 

 the presence of non-oleaginous seeds prevents the crusher from 

 expressing as large a proportion of the oil in the mixture as he 

 otherwise would, and hence it comes that when seeds containing 

 very different proportions of oil are pressed, about the same resi- 

 due of oil is left in the cake. 



Silesian Linseed. — An excellent sample, consisting of large, 

 plump grains, 1000 seeds weighing 11944 grains. It contained 

 584 per cent, of foreign seeds. 



In comparing these analyses, it will be noticed that there is 

 a very considerable difference in the percentages of water found 

 in the pure and impure linseed. This is due to the seed becom- 

 ing dry during the picking out of the impurities. This process 

 is a slow one, several hours being required for the purpose of 

 picking the necessary quantity, and as during the whole of this 

 time the seed remains spread out in a thin layer, the effect in hot 

 and dry weather is very marked. This is an unavoidable con- 

 sequence of the mode in which the experiments are made, so 

 that in practice the cake actually obtained in this case would 

 contain more water than is here given, and be somewhat inferior 

 to the analysis, though still of excellent quality. 



Messina Linseed. — This sample of seed was the finest to the 

 eye, and composed of the largest grains of any of those analysed, 

 each seed weighing nearly 2 \ times as much as those of the Irish 

 linseed. It was very bright and clean-looking, but nevertheless 

 contained 8 - 50 per cent, of impurity. Analysis gave — 



