502 PROCEEDINGS OF THE CHEMICAL DEPARTMENT. 



remarkable, also, that the three samples of Calcutta linseed are 

 the only cakes falling below 4 per cent, of nitrogen, and that all 

 the European samples exceed that number, with the exception of 

 one from Memel of very inferior quality. I have always been 

 in the habit of assuming that an oil-cake of the highest quality 

 should contain about 4*5 per cent, of nitrogen, and that which 

 falls below 4* must be looked upon with suspicion ; while 

 at 3 - 5 it is almost certain to be adulterated, or at least, like some 

 of these samples now analysed, be mixed with considerable 

 quantities of the seeds of weeds. So far this opinion must be 

 modified, for we see that an oil-cake may be pure, and yet contain 

 only 3 '5 5 per cent, of nitrogen. But though this may be the 

 case, I must say that among the very many commercial oil-cakes 

 analysed by me, I have never met with a pure sample contain- 

 ing so small a quantity of nitrogen. I believe this to be due to 

 the fact that it is a practice of the trade to mix different kinds 

 of linseed in crushing. I have been told, indeed, that this is 

 particularly attended to with Calcutta oil-cake, which is known 

 to yield a large amount of fibre, and is always mixed with some 

 of the finer varieties, so as to diminish this peculiarity. How- 

 ever this may be, it must not be forgotten that a pure oil-cake, 

 with little more than 3 - 5 per cent, of nitrogen, is possible. It is 

 doubtless of rare occurrence, and the sample would unquestion- 

 ably be considered of inferior quality. 



On the other hand, fine samples may contain as much as 5* 

 per cent, of nitrogen. But we must guard against supposing 

 that this is in itself a proof of quality, unless we know that the 

 linseed has been free from other seeds or adulterations. If 

 merely the numerical results of the analysis are looked to, a 

 mixture of comparatively cheap articles may be made up, and 

 is made up, which imitates completely the composition of a 

 first-rate oil-cake. I have already so often adverted to this fact, 

 and pointed out that the analysis of a genuine oil-cake should 

 always state in the most distinct terms that it is made from 

 pure linseed, that I should not have mentioned it here at all, 

 had not experience taught me that it is a matter too much over- 

 looked by the farmer, and that numerous instances occur in 

 which, owing to its omission, mixtures made up of very inferior 

 matters pass muster as genuine. 



ANALYSES OF THE SOILS AND SUBSOILS ON WHICH THE 

 FIELD EXPEEIMENTS OF 1867 WERE MADE. 



In the introductory remarks which prefaced the analyses of the 

 soils of the year 1866, I went into some details regarding the kind 

 of analyses required for soils, which render any lengthened obser- 

 vations on the present occasion unnecessary. I particularly pointed 



