PACIFIC SALMON FISHERIES. 125 
OAPPING. 
The endless belt delivers the can to the capping or topping machine. 
On reaching this the can passes under a cap holding a top, the latter 
being fed in through a separate aperture, and the cap immediately 
falls with just sufficient force to put the top on the can without 
injuring either. The can is then forced out from under the capper 
by the rotation of the machine, and the next capper is brought 
around to receive another can. As the cans revolve they are carried 
under a crimper, situated directly opposite the capper, which presses 
the edge firmly around the body. While one can is being topped 
another is being crimped, after which it rolls out upon a belt on its 
side, and is taken through the acid trough. Before the tops are 
sealed the edges must be treated with a solution of muriatic acid, 
which is in a glass receptacle and is applied just before the cans are 
rolled through the acid trough on the endless belt. 
SOLDERING. 
For many years the tops and also all other parts of a can were 
soldered by hand, a long, tedious, and expensive process, which even- 
tually gave way to the soldering machine. This is composed of an 
endless chain about 6 feet long, revolving around two shafts at either 
end of an iron trough. In the bottom of the trough is the solder, 
which is kept at molten heat by a row of oil blast jets underneath. 
Between the lower part of the chain and trough is just enough room 
for the cans to pass without jamming, and they are forced along the 
trough by a chain in contact with their sides. They enter the trough 
at an angle, their bottoms slightly inclined, which causes the top 
rim to be submerged in solder, thus distributing it evenly all around 
the edge. 
In passing through the trough the cans make about half a dozen 
revolutions, which cause the tops to become very hot, and it is to 
prevent them from being blown off by the pressure of the steam 
which quickly generates that the center hole in the top is made. The 
“chip” previously mentioned prevents the hole from being choked 
with salmon. 
A soldering machine having, instead of the endless chain to give 
motion to the cans, a metal spiral running the length of the machine 
and revolving on an axle through the center, is used in some can- 
neries. Each loop grasps a can and follows it to the end, thus giving 
the cans the proper motion and preventing them from rolling side 
by side and lapping the solder over the ends, as is frequently the case 
with the chain machines. 
A few canneries use a revolving cooler, which has a disk upon 
which the cans rest. This disk is filled with running water, and 
