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By the abstraction of moisture, as occurs during the process 
of fruit drying or of dessication of meat, one of those essentials is 
removed, fermentation or putrefaction cannot take place, and the 
articles of food is preserved against decomposition. On the other 
hand, if warmth is needed for the satisfactory evolution and work- 
ing of those micro-organisms which cause fermentation or decom- 
position, it may either be insufficient or too cold, and then they 
remain inactive or dormant, or it may be in excess or too hot, and 
in that case their life is suspended or destroyed. 
On these principles are based the keeping of meat, milk, butter, 
etc., by freezing, or of the sterilising of wine, with a view to their 
better keeping, which is effected by heating it up rapidly to 150° 
F. (65° C.), and also rapidly cooling it to the normal tempera- 
ture. This process is known as “pasteurisation” after the name 
of the scientist who first suggested it and proved its efficiency. 
By an application of the same process, we find, in canning, a 
cheap, ready, and practical way of destroying germs of decomposi- 
tion from the articles of food we seek to preserve. How to success- 
fully achieve that end without materially dsetroying the natural 
flavour and appearance of the goods to be preserved, constitute the 
art of canning. 
A little experience will in this matter bring proficiency to the 
operator, and enable one to save much fruit that would otherwise be 
lost. 
The materials used for canning are much too numerous to 
enumerate, but amongst the more commonly used are—fish, oysters, 
meat, condensed milk, cream, asparagus, green peas, sweet corn, 
tomatoes; and amongst fruit—apricots, cherries, gooseberries, 
grapes, nectarines, peaches, pears, plums, pineapples, quinces, 
guavas, and many other fruits which endure stewing without injury 
to flavour or to the form of the fruit. 
Oranges, for instances, are not suitable for canning, on account 
of the peculiar bitter flavour they develop on cooking; while, on the 
other hand, sour or cooking apples are also unsuitable, as they cook 
into a pulp, and lose both their flavour and appearance on cooking. 
Besides preservation of fruit by drying or by sterilising by 
the application of heat, there is also a third way of preventing fer- 
mentation, and that is by heavy additions of spirits or of sugar; 
but these are unsuited for the purpose we have in view, and are too 
expensive. 
All three are legitimate ways of preserving fruit almost in- 
definitely. Another way also exists which is not lawful nor 
wholesome, and consists in the use of antiseptics which are antagon- 
istic to the development of ferments and other micro-organisms, 
such as salicylic acid, ete. These substances are all noxious poisons, 
