536 United States Fruit-canning Industry. 



imposed thereon, pay an internal revenue tax on each package, 

 represented by coupon stamps, the packages being marked as 

 in the case of mixed flour made or packed in the States. 

 Mixed flour may be removed from the place of manufacture or 

 from the place where packed for export without payment of 

 any tax or affixing stamps or labels thereto ; but every such 

 package must be branded or marked with the same particulars 

 as are required in cases where the product is intended for home 

 consumption. 



[(7. S. Department of Agriculture, Bureau of Chemistry, Bulletin No. 69, Part /.] 



United States Fruit-canning Industry. 



The process of preserving food by the application of heat and 

 its isolation from contact with the air was first discovered in 

 I 79S by Nicholas Appert, a Frenchman. His method was to 

 enclose fruit in a glass jar, which was then corked and subjected 

 to the action of boiling water for a time, varying according to 

 the nature of the article treated. The glass jars were, however, 

 gradually abandoned in favour of tinned cans. By the Appert 

 process, the receptacles containing the food were heated in open 

 kettles, the highest temperature obtainable by this method being 

 212 degrees Fahrenheit, or the temperature of boiling water. 

 Improvements were subsequently made in the methods, and a 

 higher degree of temperature was obtained by the addition of 

 common salt to the water. This innovation was followed by the 

 use of chloride of calcium, which made possible a temperature 

 of 240 degrees Fahrenheit. In 1874 an American invented a 

 closed-process kettle to cook the goods by superheating water 

 with steam. About the same time another American invented 

 a patent-process kettle which secured the same results by the 

 use of dry steam. By these methods, which are used at the 

 present time, any desired temperature can be obtained and the 

 heat regulated to meet requirements. 



Although the canning industry was established in three great 

 commercial centres in the United States as early as 1825, it did 

 not become of much importance until within the past quarter of 



