104 PROCEEDINGS OF THE CHEMICAL DEPARTMENT. 



alone, that is no reason why he should pay for the mixture the 

 price of linseed (which he is pretty sure to do) when he can buy 

 them separately for less. Whenever a mixture is made, the 

 farmer may rest assured that this cannot be done without en- 

 tailing some cost which he is called upon to pay in addition to 

 the market value of the materials mixed. That extra cost may 

 be greater or less according to circumstances, but it must 

 always exist. 



In order that the farmer may have some guide to direct 

 him in the purchase of cakes, I shall conclude with a few rules 

 which he will do well to observe ; and I find this the more 

 necessary, because the character and composition of good oil 

 cakes are sometimes but imperfectly understood, and I infer this 

 because I have recently been shown the analysis of a cake con- 

 taining 20 per cent, of albuminous compounds, of which I am 

 informed a large quantity was sold last season, though this fact 

 is in itself in the highest degree suspicious — so much so, that I 

 do not hesitate to say the cake must have been adulterated, 

 though I have never seen samples of it. 



1. In buying a cake, examine it carefully. It should be hard 

 and difficult to break, and its colour should not be too pale. If 

 it is soft and splits easily, it is almost certain to be adulterated, 

 and if its colour is pale, even though it may be hard, it is sus- 

 picions. 



2. Examine the analysis. A genuine oil cake of the best 

 quality should contain 11 to 13 per cent, of oil, and from 26 to 

 28 per cent, of albuminous compounds. If made from inferior 

 linseed, the proportion of the latter ingredient may be as low as 

 24 per cent, but if it falls below 23 it is suspicious, and if much 

 below this quantity, the chances are that it is adulterated. 



3. Eemember that even if it contain the full amount of 

 those substances, the cake may be made up of inferior matters 

 mixed with some substani.es rich in albuminous compounds, 

 and take care to observe whether the analysis, in addition to the 

 mere numerical results, states whether the cake is made entirely 

 from linseed. 



4. A low-priced cake is probably, though not necessarily, 

 adulterated. As a rule, the market price of a good oil cake is 

 well known, and there is no great room for variations in price ; 

 so that if a cake is offered at a rate much below the average, it is 

 scarcely necessary to say that it must be considered doubtful. 



5. Obtain from the seller a guarantee that the article is made 

 entirely from linseed without mixture, and ascertain that it is up 

 to the mark. For this purpose a full analysis is not required, a 

 careful examination being enough to detect adulteration, though 

 it will not decide as to the relative qualities of different samples 

 which are genuine. 



