30 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
making a small perforation in each. A fountain-like jet at once appears, caused by 
the steam escaping, and carrying with it some of the liquor. The vents, after blowing, 
are immediately soldered and the trays run into the second retort for final cooking. 
The reason for the two separate cooking operations is that if the cans are kept in the 
first retort a sufficient length of time to complete the booking, the steam generated 
would be so great in the cans that they would be ruined. 
At one cannery inspected, where it seemed that more attention was given to exact 
details of cooking than in some others, there was on the top of the retort a thermometer, 
connected with the interior, and a separate steam-gauge. The cans to be cooked were 
placed in the retort, the doors securely clamped, and the steam turned in. The steam 
gauge was carefully noticed until it showed 0 pounds pressure, where it was main- 
tained, by regulating the stop valve, until the thermometer registered 220° F. The 
Lacquer room. 
temperature was kept at this point for thirty minutes, when the retorts were opened 
and the cans removed. 
The second cooking at this cannery is as follows: After the cans are placed and 
the doors secured, steam is admitted until the independent gauge shows a pressure of 
12 pounds. It is then maintained at that pressure until the thermometer registers 
240°, when the temperature is regulated to 240° for 45 minutes when cooking redfish, 
or 60 minutes when cooking cohoes. The latter fish are quite large at this cannery, 
and presumably the longer period is given so that the large bones may be thoroughly 
cooked. In both cases of cooking, after the desired temperature is reached the 
pressure falls, while the temperature is held at the proper point. 
After the cans are taken from the second retort the grease and dirt on them are 
removed by a lye bath, the lye is next removed by a fresh water bath, and the cans 
