PRESERVATION OF FRUIT. 379 



sugar should be used for light-colored fruits, and light brown 

 sugar for dark-colored, and that the syrup must be perfectly clear, 

 and, hence, very carefully skimmed in boiling. In most factories 

 the syrup used consists of 1 Ib. of sugar dissolved in 1 pint of 

 water. The filling of the cans with the fruit and syrup, the latter 

 being generally kept warm, is effected with the assistance of a 

 scale, so that each can has exactly the weight upon which the 

 selling price is based. The caps previously provided with a hole 

 the size of a small pea are then soldered upon the cans. The hole 

 in the cap serves for the escape of the air during the succeeding 

 process. 



Different kinds of apparatus are used for the expulsion of the 

 air by heating the cans. In large factories a steam retort is used 

 which resembles in shape a ship's steam boiler. It is provided 

 with a door closing air-tight, and is divided in the centre so that 

 it can be filled either half or entirely with steam, as may be 

 required. The cans to the number of from 400 to 600 are placed 

 upon trucks which run upon rails leading into the retort. Eight 

 such trucks can be introduced at one time, so that it is possible to 

 steam from 30,000 to 40,000 cans per day. The retort being filled 

 the door is closed and the pipe communicating with the steam 

 boiler opened. The cans remain in the retort from 15 to 30 

 minutes, according to the variety of the fruit : berries 1 5 minutes, 

 stone-fruits 20, apples and pears 25, quinces and tomatoes 30. 

 The door is then opened, and after the steam has some what dispersed 

 the trucks are quickly pushed to the tin-shop, where the cap-holes 

 are soldered up. To cleanse the cans and make them shiny they 

 are next put in a bath of soda water and then rinsed off with 

 cold fresh water. They are then transferred to the store room, 

 where they remain standing quietly for one week, when they are 

 tested by striking the cap of each a short sharp blow with a 

 wooden hammer. If everything is in order, the cap sinks slowly 

 down, but if it is elastic and jumps back the can is what is called 

 a " swellhead," and is returned to the tin-shop for repairs and is 

 then again steamed. The perfect cans are labelled and packed 

 and are now ready for market. 



Another apparatus which can be highly recommended for small 

 factories consists of a round iron plate resting upon a brick basis 



