492 



On the Composition of Linseed Oil- Cake, 



occur in the composition of the seed adequate to account for 

 similar differences in the composition of the cake. Thus an 

 answer is afforded to the third question proposed, and indirect 

 evidence supplied in the negative to the question of adulteration,, 

 That this subject may be as complete as possible, I insert 

 here the mean of two ash analyses of linseed. 



Table 11. — Mean Composition of the Ash of Linseed : — 



Silica 



1-45 



Phosphoric Acid . , 



38*54 



Sulphuric Acid 



1.56 



Carbonic Acid 



•22 



Lime 



8-40 



Magnesia . . . 



13-11 



Peroxide of Iron . . 



•50 



Potash 



34-17 



Soda .... 



1-69 



Chloride of Potassium . 





Chloride of Sodium 



•36 





100-00 



The composition of the ash of linseed, and that of linseed- 

 cake, should exhibit no other difference than that produced by 

 the accidental introduction into the latter of a little sand and dirt, 

 as well as of some portion of the substance of the stones used in 

 grinding the seed. Accordingly we find that, making allowance 

 for this circumstance, the per-centage composition of the ash of 

 the cake approaches very nearly what would be expected.* In 

 quantity of ash, the cake of course exceeds the linseed in propor- 

 tion to the oil expressed. Where the per-centage of ash in the 

 cake is high, it is mostly due to its containing more sand, as in 

 the case of specimen 25, which is given in the table at p. 484. 

 We may conclude this subject by recapitulating the conclusions 

 to which we have been led : — 



1. That samples of cake differ considerably both in the pro- 



portion of albuminous matter and of oil contained in 

 them. 



2. That in respect to the former (the albuminous matter) 



there would appear to be no general distinction between 

 home-made f or foreign cakes. 



3. That in the proportion of oil there is reason to believe a 



general distinction does exist, more especially between 

 English and French cakes, and in favour of the former. 



* Except in the potash — some of which seems to have been lost — for whilst in the 

 ash of the seed it stands to the phosphoric acid in the relation of 34 to 38^, in the cake 

 it is as 23i to 32, which is a very different proportion. Is potash expressed from the 

 seed in the form of soap dissolved by the great excess of oil? 



f I say " home-made." This term merely implies that the seed was pressed at home 

 — there being no evidence to show that the seed in any of the English cakes described 

 was other than Foreign seed. 



