Dried and canned foods maintain the health of dwellers in the Yukon, or of arctic 

 or tropical explorers, and thus contribute to the world's progress. The lives of infants 

 and invalids may hang upon this means of securing for them suitable nutrition under 

 adverse conditions of climate, temperature, or disease. 



(Fro. 1.) 



Specimens of canned foods in 



common use. 



Figs. (1), (2), (3), (4), (5), (6), (9). and (10) are reproduced, by kind permission of Messrs. Sidgwiclt & 

 Jackson, London, from "Household Foes," by Alice Kavenhill. 



Some form of preservation is necessary for foodstuffs, such as meat, vegetables, 

 eggs, or fish, which constantly have to be transported long distances ; half across the 

 world, indeed, to meet the needs of some crowded community unable to supply its 

 enormous demands locally. The food-supply of the capital city of our great Empire, 

 with its seven million inhabitants, is drawn from all over the globe. To trace the 

 sources of the ingredients in our own Christmas pudding will be found to constitute 

 quite a fine exercise in geography ! 



AN IMPORTANT POINT IN FOOD-PRESERVATION. 



Too much insistence cannot be laid upon this point in connection with the wholesome 

 preservation of food. It must not be subjected to any treatment which may interfere 

 in the slightest degree with the process of digestion or which will disguise the fact if 

 decay has already set in. Preferably, too, the appearance of the food should not be 

 affected, though this is of minor importance. 



To discover how far these points are taken into consideration, it will be well 

 briefly to review the 



METHODS OF FOOD-PRESERVATION IN GENERAL USE. 



These might be divided into two sections : 



(1.) Commercial methods of food-preservation, carried out on a large scale, of 

 which the products are for sale : 



(2.) Domestic methods, carried on in the home, for family use only. 



But so many of the processes employed are common to factory and home, varying 

 only in the quantities of food materials handled, that it is possible to pass the methods 

 and their reasons in review without such distinction. 



Before doing so, however, it is important to have a clear idea of 



WHAT DECAY IS. 



For the whole object of the preservation of food is to postpone what we call decay. 

 Those changes in food which alter its character and often affect its appearance, which 



