Annual Report for 1892 of the Consulting Chemist. 785 
Attention has also been especially called to the frequent occur- 
rence of cotton-wool both in undecorticatecl and in decorticated 
cotton-cakes. This has proved objectionable and dangerous in 
feeding, an^ I am quite sure that its occurrence in cakes ought 
to be particularly guarded against. 
In addition to the samples which have been examined on 
behalf of Members of the Society, the Laboratory has been made 
use of during the year in connection with the Woburn experiments, 
as also for analyses referring to experiments of Local Agricultural 
Societies, and for several matters of agricultural investigation. 
Linseed Cakes. 
Purity of Cakes . — I have recently had considerable correspondence 
with agricultural bodies and cake manufacturers in foreign coun- 
tries, more especially in Holland and Denmark, with regard to the 
possibility of stating the exact percentage of impurity which may 
occur in linseed and other cakes. I have had to reply that there 
exists at present no means of directly estimating the quantity of 
impurity, and I would now point out that the most that can be safely 
done is to say whether a particular cake contains more or less 
impurity than one should have which has been made from good 
seed subsequently well screened. I have previously had occasion 
to insist that any statement as to “ 95 per cent, purity ” is mis- 
leading, and that I could not accept it, inasmuch as it is impossible 
to determine the exact percentage of impurity, and because it leaves 
entirely out of account what the nature of the remaining 5 per 
cent, may be. This latter may be composed of materials directly of 
an injurious character, the cake, nevertheless, still remaining “ 95 per 
cent, pure.” 
I can, therefore, only admit the term “ pure,” thereby meaning 
the state of purity which an honest manufacturer can readily, and, 
as a matter of fact, does, obtain by using good seed and carefully 
screening it. 
Percentage of Oil . — Anotlier question which has often been brought 
before me is that of the guarantee of the percentage of oil in linseed- 
cakes. It is a habit of some manufacturers to guarantee a definite 
percentage of oil, hoping thereby to increase the sale of cakes of their 
particular make. To this I have no objection, more especially since 
a cake rich in oil means, as a rule, one which is soft and in good 
mechanical condition, as well as high in quality. But, as any one 
with experience knows, it is impossible to avoid vai-iatioms, not merely 
in a whole delivery of cake, but even, within certain limits, in difierent 
portions of any one individual cake. Hence, whilst I am by no 
means in favour of compelling the makers to guarantee the per- 
centage of oil in their cakes, yet, if they will do so, they must be 
careful not to bind themselves within too close limits, for if a 
certain percentage is guaranteed, the vendors must be prepared to 
