SALMON FISHERIES OF PACIFIC COAST. 53 



to 2 inches, and are scraps from the sheet tin used in making the 

 tops of the cans. The shape is of no particular importance so long 

 as the pieces are long enough to cover the hole in the top of the can, 

 or the cap as it is called. 



CAPPING. 



The endless belt delivers the can to the capping or topping ma- 

 chine. 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 as the cans are rolled 

 through the acid trough on the endless belt. 



SOLDERING. 



For many j^ears the tops and also all other parts of a can were sol- 

 dered 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 a can 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 giv- 

 ing the cans the proper motion and preventing them from rolling 



