FISH-SCRAP FERTILIZER INDUSTRY OF ATLANTIC COAST. 
49 
strictly between menhaden oil and other so-called fish oils, such as 
those obtained from the whale, porpoise, and seals, as those from the 
latter three sources lack those qualities possessed by menhaden oil 
to a marked degree, which would classify them as drying oils. Their 
admixture with drying oils, such as tung and boiled linseed oils, 
does not avail, for while they may appear to have dried they become 
sticky again in the presence of humid air. 
In the subjoined table are given the specific gravities and iodine 
numbers of several oils commonly classed as fish oils. The iodine 
numbers are determined by the method of Hubl. 
Table XIV. — Specific gravities and iodine numbers of fish oils. 
Kind of oil. 
Specific 
gravity 
at 20° C 
Iodine 
number. 
Kind of oil. 
Specific 
gravity 
at 20° C 
Iodine 
number. 
0.919o 
.9168 
.9187 
.9196 
.9233 
.9227 
136.1 
125.0 
142.9 
147.3 
132.3 
143.0 
Menhaden oils: 
Extra bleached winter . . . 
Bleached, refined 
Regular 
0.9237 
.9273 
.9249 
.9250 
No. 1. Filtered whale oil 
No. 2. Filtered whale oil 
Cod oil 
150.4 
161.2 
165.7 
154.5 
Seal oil, water white 
The authority quoted says further : 
The oil that gives the best and most lasting results for paint purposes is the 
menhaden oil, and the winter-bleached variety is the one .that should be rec- 
ommended. This is an oil fairly pale in color, with an iodine number of 150 
or over, and with little or no fishy odor; in fact, I might say that in the pur- 
chasing of fish oils for paint purposes it is well to beware- of a fish oil that has 
the so-called characteristic fishy odor. I have not yet satisfied myself as to the 
cause- of this odor, but, so far as I have reached in my investigation, I am 
inclined to believe it is due to phosphorous decomposition compounds. The re- 
sults which I have obtained from the proper grades of fish oil — and I am glad to 
say that there are several manufacturers sufficiently intelligent to market the 
oils that are very desirable — warrant me in saying that fish oil in the hands 
of an intelligent manufacturer, and used up to 75 per cent, produces excellent 
results for exterior purposes. For interior purposes fish oil does not seem to 
be desirable, for it gives off noxious gases for a long time. 1 
It is recommended that for exterior work three parts of fish oil be 
mixed- with one part of linseed oil. The mixture is nonhygroscopic — - 
when dry it remains dry — and the results obtained with it are de- 
scribed as excellent and lasting. The iodine number, it is main- 
tained, is an index of the suitability of fish oils for paint purposes. 
It profitably may be substituted for linseed oil in a number of appli- 
cations. It is more resistant to the action of heat than linseed oil, 
and hence is especially adaptable to use in painting ironwork such 
as boiler fronts and smokestacks. It holds up better in a moist cli- 
mate, such as that existing in proximity to the seashore. Its use is 
1 Toch, loc. cit. 
