22 THE CANNING OF FOODS. 



WASHING AND FILLING THE CANS. 



The cans should be washed just prior to being used. In the ship- 

 ping and storing, more or less dirt and dust find lodgment on the 

 inside, and washing is the only method of removing it. The quantity 

 of dirt which can be obtained from a thousand cans is usually a matter 

 of surprise. The work is done very effectively at the present time by 

 machines. The filling may be done by hand or by machine. There 

 are many products, especially fruits, which can not be successfully 

 filled by machine because of crushing or otherwise injuring them. 

 When filled by hand the contents should be regulated by weight 

 rather than by volume, so that the finished product will be uniform. 

 If the filling be done by machine, care should be taken to get the best 

 results possible. It is illogical to use care in peeling a 3-inch tomato 

 and then have it squeezed through a 2-inch opening in front of a 

 crude plunger; or that great care should be exercised in washing and 

 blanching peas, which are to be run through a filler that will cut or 

 crush enough to make a muddy liquor. Machines should be designed 

 to fill with reference to the nature of the product and not to be merely 

 " can stuffers." Vast improvements have been made in filling ma- 

 chines in the past few years, so that most of the work can be done 

 with nicety and precision. All filling machines operate upon the 

 principle of delivering a certain volume rather than a given weight, 

 and for most products this method is very satisfactory. In all cases, 

 whether the can be filled by weight or volume, the amount of ma- 

 terial used should be all that can be put in the can in first-class con- 

 dition. Brining and siruping have also been improved, the old- 

 fashioned unsanitary dip box giving way to a sanitary filler. 



EXHAUSTING. 



After the can is filled the next step is exhausting. This is best 

 for all articles packed cold, but is unnecessary for corn, peas, or prod- 

 ucts which enter the can hot or are covered with a hot sirup. Ex- 

 hausting consists in passing the filled can through a steam box and 

 heating the contents to 160 F. or above, the preference being for 

 180. The time required for exhausting will vary from one to three 

 minutes. 



CAPPING AND TESTING FOB LEAKS. 



Open-top cans are sealed by a special machine known as a double 

 seamer. The lid is pressed into place and steel rollers crimp it on 

 without acid or solder. This action is automatic, a single can at a 

 time, but at the rate of 30 per minute, or 1,800 per hour. Cans with 

 solder tops are sealed by automatic machinery, 12 at a time, 85 per 

 minute, or 5,000 per hour. The top is wiped, the cap placed on, acid 

 applied, the hot soldering irons drop into place, and the vent is after- 



