On food : four Cantor lectures, delivered before the Society for the Encouragement of Arts, Manufactures, and Commerce / by H. Letheby.

Henry Letheby

Date:: 1868

Credit: On food : four Cantor lectures, delivered before the Society for the Encouragement of Arts, Manufactures, and Commerce / by H. Letheby. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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$LECTURE ly.—Delivered Monday, February, 10, 1868. PRESERVATION OP FOOD—TJNAVHOLESOME AND ADULTERATED FOOD. It requires no argument to show that the preservation of food is a matter of great public importance ; for it not only enables us to provide against actual want in periods of unusual scarcity, but it also affords the means of equalising the distribution of food at all times, so that the excess of one country may be used in supplying the deficiency of another. In the pastoral districts, for example, of Canada, Australia, Tasmania, the Cape of Good Hope, Mexico, the Argentine Republic, and the BrazUs, thousands of tons of meat are always available as food, and yet they are lost to us because of the difficulties of preserving it. In South America, at least two millions of beasts are annually slaughtered for the fiit, sldn, and bones, the flesh of which could be supplied here at less than 2^d. per [pound. So also in Australia, the amount of meat available as food is practically inexhaustible. Last year Mr. PHlpott stated to the Food Committee of the Society of Arts, that he himself was in the habit of melting down from 1,000 to 1,500 sheep daily for four months together; and that in the vast districts of rich pasture-land from Victoria to Brisbane, there was an imlimited supply of the very finest meat—all of which was at present entirely wasted, because of the difficulty of disposing of the flesh; and, therefore, the carcasses of the animals were molted down for fat. A bullock in Australia, he said, costs only from £3 to £4; and legs of mutton of the veiy best quality were, when salted, sold for three shillings a-dozen. If some simple and prac- ticable means could be devised for preserving such meat, it might be supplied to our markets at less than 3d. a pound. Until recently the only process employed for this pur- pose was the rude' method of salting tho meat, but the deterioration of it was so obvious, and the distaste for it so general, that it was only practised to a limited extent, and for occasions when fresh meat could not be obtained. Tho salt junk of the navy in olden time was a good example of the wretchedly unwholesome and indigestible meat prepared, for it could hardly be called preserved, by this process. Recognizing, therefore, the necessity for a bettter means of preserving food, tho naval authorities of every coimtry appealed to science, and gave the largest encouragement to inventors. A further stimulus to invention was created by tho necessity for supplying our Arctic explorers with good and wholesome food during their long Avinter residcneo in tho frozen seas of tho north; and as that inquiiy was set on foot, not merely for the purpose of discovering a north-west passage to our possessions in America, but also with tho view of prosecuting scientific research in almost inac- cessible regions, an imusuul inducement was oflerod for the preparation of such food. The demand thus created was soon acknowledged by science, and was also met by tho practical skill of tho manufacturer, so that tho Arctic voyager went confidently on his journey, know- ing that he had other food than the unwholesome junk of the navy. The earliest preparations supplied to him mixtures of dried meat with sugar and spico were {pemmtcan), but after a time they were fumifihed with, fresh meat, preserved in air-tight cases. At first tho supply was chiefly for voyagers in cold countries, but: when the value of this method of preservation became known, the Eui'opean residents of hot climates, as i , India, eagerly sought for the fresh foods which they - were accustomed to use in their own countrj^, and thus ■ an additional stimulus was given to this process of! manufacture. At the present time it has acquired] - gigantic proportions. I have before me a list of the specifications of patents i relating to the preservation of food, from the year 1691: to the end of 1855, and I find that onlj' one wasi described in the seventeenth century, and three in the< , eighteenth, while as many as 117 were specified in thai first 55 years of the present century. Invention, how- ever, has not been prolific of new processes, for it mainly confined to an application of one or two simple j elementary principles—26 of the patents, for example, are for the preservation of food by drying; 31 byi. excluding atmospheric air; 8 by covering the food witi J an impervious substance, as fat, extract of meat, gelatine^f collodion, &c., and 7 by injectingmeat with various sidtsl; But before we proceed with the examination of thesff I processes, it will be advantageous to inquire a little inta T the circumstances which favour organic decompositions It would seem, from experiment and observation, that; three concurrent conditions are absolutely necessary- foi' .: active putrefaction—^namely, the presence of much! .. moisture, the access of atmospheric air, and a crrtaiii temperature, as from about 40° to 200° of Fahrc; any of these being absent, the organic substance i decay. AH preservative processes must, therelorr depend on an application of one or other of tin? principles; and perhaps we may add a fourth—n: the action of chemical agents. Let us review th. detail. 1st. T/ie preservation of sttbstances hy drying thar - very ancient date. In our anatomical museums wi long known that specimens of tlie animal body n preserved for an indefinite time by drj-ing their,, then varnishing them so as to exclude moisture, is a dissection prepared in that manner, which hns used for lecture illustration at tho London Ho.'jpit more than half a century, and yet it is as sound as ■ it was made. In warm climates it has been a pr for ages to preserve fish, and even meat, by drying v —the meat being cut into strips and exposed to the of warm drj- air. Chanpii or South American which you see hei-e, is an example of it. It is ob; from animals that arc grass-fed, and they are kil': pithing and then bleeding them. Du-ectly the hivic i taken ofi, tho flesh is stripped from the bones and allowed to cool. It is then placed on a table, and jerked, or cu up into thin slices, which are piled up in heaps vn\\ alternate layers of salt. After standing twelve horn - t meat is turned, and fresh salt is added where • The next day the salted strips are placed upon hurdlo&j$