490 



PROCEEDINGS OF THE CHEMICAL DEPARTMENT. 



will be afterwards explained, the composition of the cakes which 

 these samples wonld yield. 



It is sufficiently obvious that this mode of proceeding is very 

 laborious for to arrive at perfectly fair averages of the composition 

 of all the different varieties of linseed, some hundred analyses 

 would be required ; and as this would have necessarily occupied 

 a very long time, it became necessary to limit the inquiry, and I 

 therefore restricted myself, in the first instance, to twelve samples 

 of linseed, selected so as to show both the differences of locality 

 and of quality. 



The first point to be ascertained was the amount of impurity 

 in each sample, which was most easily effected by spreading it 

 •out on a sheet of paper, and with a fine camel's-hair pencil 

 brushing the grains of linseed to one side of the sheet and the 

 impurities to the other. The impurities consisted generally of 

 small seeds, such as wild mustard, various species of the genus 

 Polygonum, among which buckwheat (Polygonum Fagopyrwm)wa& 

 ■occasionally observed, and a great variety of small seeds, which it 

 would be impossible to recognise without growing them, which I 

 had no means of doing. In the Indian samples, the seed called 

 Indian rape was recognised. 



The following table gives the percentages of impurities in the 

 different samples, and their prices, so far as they are known to 

 me. 



The inspection of this table shows very distinctly that no 

 i-elation exists between the purity and price of any sample of 

 linseed ; for we see that the Irish linseed, which is practically 

 pure, containing only 1*6 per cent, of foreign matter, brings only 

 50s. per quarter, while ordinary Calcutta seed, with 30 percent, 

 of impurity, sells at 58s. ; and of two samples of Calcutta seed, 

 sold at the same price, one contains 5 and the other 19 per cent, 

 of impurity. It is difficult to understand how this should occur. 

 It certainly cannot be due to ignorance, for though the eye cannot 

 estimate with accuracy the amount of impurity in any sample, 

 even the most careless observer cannot fail to distinguish the great 

 difference between 5 and 19 per cent, of foreign seeds. 



