E. D. Clark and L. H. Almy 495 
A fundamental relation, which is indicated not only by these 
results but likewise by the results obtained by Atwater (1), is 
that as the fat content increases the water content decreases, the 
protein remaining practically the same. This is strikingly shown 
in Table VIII in four species of fish whose fat content varies from 
0.15 per cent to 14.48 per cent. The fat-free solids, which con- 
sist of nitrogenous and mineral constituents, vary but slightly 
from the mean value of about 21 per cent, showing that the gain 
or loss in fat is compensated for by a corresponding gain or loss 
in water rather than protein. 
TABLE VIII. 
Relation between the Amounts of Fat, Water, and Nitrogen in the Fiesh of 
Fish, 
Kind of fish. | Water. Solids. Fat. ae . 
per cent per cent per cent per cent 
Ped STS el) A pal pen ee ie age aa 79.10 20.90 0.15 20, 75 
SPST ICs 2) UN ae el 70.96 29.04 8.10 20.94 
Spans Mackerel... ie Kae ees. 66.99 33.01 12.59 20.42 
eliketel cts 2 SRA Uae ae te ROS De ee 64.68 35.32 14.43 20.89 
A study of the values obtained for the fat constants of the fish 
oils shows that they are fairly uniform for the different species 
analyzed. These constants will average, as a rule, approximately 
as follows: 
; : 25 
Specific gravity at 5 BREA aloe oye ty 5 Cd cahn fa asad st Sagi Se 0.9220 
eee Ee T EL SAGELOIE PU aot cand 0S deseors wi che ode, Biaxcinvane sche “ered t 1.4750 
PARODY Ol ot Pe ced ee ee, EN oA aN encl ec kn Soap h onde SG 110-130 
Pee RORTE CHU LOTION Cle OO ethereal eta te Feats alt Win si spn) cig tons 180-190 
They are characteristic of fish oils commonly classed with dry- 
ing oils. | 
A study of the figures obtained for the acid value of the oils 
(Table VI) shows that, in general, when fish are low in percent- 
age of fat, the acid value will be high, and when the fat con- 
tent is high the acid value will be low. This seems to point to 
‘the presence in the tissues of fish, in a more or less constant pro- 
portion, regardless of the fat content, of an acid substance sol- 
