96 U. 8S. BUREAU OF FISHERIES 
dried. Accurate account was kept of the weight of fish before and 
after frying. Individual lots of fish were cooked 8 minutes in oil 
having a temperature close to 230° and were allowed to drain over 
the bath 8 minutes before being removed and weighed. 
Enough water was added to each bath, so that it came almost to 
the bottom of the steam coil. At the beginning of the experiment an 
excess of oil was used; later, however, just enough oil was floated 
on the water to a little more than cover the basket of fish immersed 
in it. 
In order to identify the two lots of oil, the baths are referred to as 
bath [ and bath II. The oil in bath I was not treated, except that it 
was separated from the water and ‘‘foots” * after a day of frying. 
Most of the oil in the “foots”? was recovered by placing them in a 
100 
90 
80 
70 
60 
PER CENT FISH OIL 
mn 
to] 

HOURS 
Fic. 21.—Increase in fish-oil content of oil used for frying fat fish. Data obtained from 
Table 20, p. 166 
bottle and heating for an hour or so in boiling water. The clear oil 
hat formed was then floated off and added to the other oil. 
In bath II the oil was separated similarly, then returned to the 
bath with enough clean water to cover the steam coil. In this manner 
the water was boiled by the steam, and this caused the oil and water to 
form an emulsion. In order to break the emulsion, water was run 
out until the steam coil was in the emulsion. Steam was then turned 
on and this caused the emulsion to ‘‘break.’’ Further heating drove 
the remaining water out of the oil. 
Fifty cubic-centimeter samples of oil were taken from each bath 
after a batch of fish had been fried. From bath II an extra sample 
frequently was taken after the oil had been cleansed. These samples 
were placed in corked bottles and later examined and analyzed. 
Equal quantities of the same batch of cottonseed oil were placed in 

27 'The layer of oil and water emulsion that forms between the oil and water, 
OEE IDE! bt Ge es Pa. 
