SEA-FISHERIES LABORATORY. 127 
Water. Fat. Proteid. Ash. Total. Nitrogen. 
=: 58°8 11°3 24:0 3°7 97°8 14-8 
eee is a= 55°3 13°6 25°6 52 997 15°4 
= eee 58°2 9°8 25°9 5°9 99°8 16-0 
ie Cee 59°9 mM: 7 24°5 3°2 99°3 16:0 
ee 58°6 78 27°4 56 99-4 15-7 
Oo Hiechly Smoked Sprats. 
Brightlingsea fish. (1) the whole fish ; (2) the “ flesh ” only. 
Water. Fat. Proteid. Ash. Total. Nitrogen. 
eee. 35°1 23°7 29°6 10:0 98-4 151 
1 ae 39°1 16:1 32°2 9°8 97:2 14:7 
In all the above analyses “ Proteid ” means “ nitrogen x 
6:25,” and “Fat” means “ Carbon-tetrachloride-extract.” 
“ Nitrogen ” is the N found by Kjeldahl analysis and calculated 
on the quantity of ash-free, fat-free, dried residue taken. 
If the “ totals,” that 1s, °4 water + °% fat + % proteid + 
% ash, be examined, it will be found that they may vary 
between about 97 and 103 as extremes, a difference of + 3 %/ 
from. that which should have been obtained on the assump- 
tions that everything present in the tissues taken can be 
estimated as water, fat, ash and N x 6:25. Where the total is 
much less than 100 % the “nitrogen ” is markedly less than 
16 %, and vice versa. It was assumed that fish proteid contains 
16 % of N though it was evident that it did not—in general. 
In fresh summer-caught herrmgs such as those examined 
here, the N %%, as defined above, was about 14°5. In fresh 
winter-caught herrings it was about 15-5. In fresh winter- 
caught sprats it was about 16-2. 
In salted, smoked and hermetically-sealed sprats: and 
herrings the N % depends, to some extent, on the season of 
capture of the fish canned, and on the methods of conservation. 
The apparent errors of analysis as indicated by the above 
tables are, therefore, to be traced to the use of the factor 6.25, 
