BY-PRODUCTS 371 



of crushing or injury. The fruit should be placed in cans at once 

 or it will discolor. The amount of material used for each can 

 should be all that can be put into it in first-class condition, with 

 hot water added immediately to make the can full. 



6. Sealing cans, such as open tops, by a special machine called 

 a double seamer is practical in some canneries. The lid is pressed 

 into place, and steel rollers crimp it on without acid or solder. This 

 is all done at the rate of 30 cans a minute, or 1800 per hour. 

 Cans with soldered tops are sealed by automatic machinery, 85 a 

 minute and 5000 an hour. Such machinery will wipe the top of 

 the can, place the cap on, apply the acid, solder and close the 

 vent, all in one series of operation and without the hand touching 

 any part of the can. 



7. To test for leaks the cans are submerged in a bath of 

 boiling water. A scries of air bubbles issuing from the can indi- 

 cates a defect. 



8. Apples are processed about eight minutes at 212 degrees F. 

 for No. 3 cans and about ten minutes for No. 10 cans. This 

 processing consists of placing the cans in a vat or retort, sometimes 

 submerging in boiling water, and then turning on steam for the 

 required time. 



9. After processing with water the cans should be cooled 

 quickly. Unless this is done the processing may continue too long 

 and overcook the contents. 



10. The cans are stored away and later labeled, boxed, and 

 shipped wherever required. 



