When an organic substance, like the flesh of animals, is heated to the boiling-point, it loses the property of passing into a state of fermentation and decay. Fresh animal milk, as is well known, coagulates, after having been kept for two or three days, into a gelatinous mass; but it may be preserved for an indefinite period, as a perfectly sweet liquid, if it be heated daily to the boiling-point. The knowledge of this effect of an elevated temperature has given rise to a most important branch of industry,--namely, the preparation of preserved meats for the use of the navy and merchant service. At Leith, in the neighbourhood of Edinburgh, at Aberdeen, at Bordeaux, at Marseilles, and in many parts of Germany, establishments of enormous magnitude exist, in which soup, vegetables, and viands of every description are prepared, in such a manner that they retain their freshness for years. The prepared aliments are inclosed in canisters of tinned iron plate, the covers are soldered air-tight, and the canisters exposed to the temperature of boiling water for three or four hours. The aliments thus acquire a stability, which one may almost say is eternal; and when a canister is opened, after the lapse of several years, its contents are found to be unaltered in taste, colour, and smell. We are indebted to the French philosopher Gay-Lussac for this beautiful practical application of the discovery that boiling checks fermentation. An exclusive salt-meat diet is extremely injurious to the health; and, in former times, thousands of mariners lost their lives for the want of fresh aliments during long voyages. We are sorry to say that the preserved meats are sometimes carelessly prepared, and, though the statement seems incredible, sometimes adulterated. Dr. Lankester, who has done so much to expose the frauds of trade, that he ought to be regarded as a public benefactor, says that he has seen things which were utterly unfit for food, shipped as preserved meats. Surely, as he observes, there ought to be some superintendent to examine the so-called articles of food that are taken on board ship, so that the poor men who have been fighting our battles abroad may run no risk of being starved or poisoned on their way home.
Reading list for 2012!
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Believe it or not but I have been reading books in 2011. Mostly on my
Kindle, but I did forget to update this blog. However I thought it would be
good to r...
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