SEA-FISHERIES LABORATORY. 9] 
than fats are thus extracted was not investigated. Lecithin, 
for instance, may be thus dissolved out from the flesh, but it 
is not certain that the quantity extracted is significant—in a 
dietetic mvestigation. Nor was the difference, if any, in solvent 
power, of ether and carbon tetrachloride studied—probably it 
does not matter. Strictly speaking we ought to speak of 
* extract’ rather than of“ oil ” or“ fat,” but the latter terms 
may be used. 
The dried flesh of the herring is very friable and easily 
crumbles to an impalpable powder. It was so friable that it 
was unnecessary to powder the dried substance before extraction 
(though this was done in some cases). Far different is the 
dried flesh of some other fishes, the plaice, for instance. 
The water-free, fat-free residue. 
After extraction the plugged thimble was replaced in its 
own weighing bottle and dried in the steam oven. The 
weight of the residue was found by difference and the total, 
water + oil + residue (three weighings), was used as a check. 
As a very general rule it did not differ by more than 0-5% from 
100. Very often the error was in excess, and was regarded as 
the gain in weight due to oxidation of the oil (though this is a 
matter requiring further study). If there were wider deviations 
the analyses were repeated. 
As a rule two samples were taken. The contents of the 
thimbles were taken out, powdered in an agate mortar, re-dried 
and stored. Usually there was enough to enable both proteid 
and ash estimations to be made. If not, the reserve of dried 
material (when this had been prepared) was used for these 
purposes. 
The proteid estimations. 
Proteid was estimated by the Kjeldahl process. None of 
the 1914 samples were examined in this way, but all the 1916 
dry, fat-free residues were kept with the object of estimating 
