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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$pig diu-ing the summer, and Irill it and salt it for tlio winter, llama and tonguos are treated in like manner ; and so are fish when they are plentiful among the in- habitants of our coasts. As far back as 1800 a patent was granted to Mr. Benjamin Batley for cxu'iug and pre- serving herrings and sprats by salting them; and it would seem that his process was very successful, for in the following year ho obtained a patent for the like treatment of other fish. The dainty caviare of the Eussian is nothing hut the salted roe of the sturgeon. Even vegetables may he preserved in salt and water, as in the case of olives. Other saline substances, saltpetre, acetate of ammonia, sulphite of potash, or soda, muriate of ammonia, &c., are also good preservative agents, and are the subjects of several patents. Here is a specimen of moat pre- served by wetting it with the solution of one part of acetate of ammonia and nine of water; and here another, which has heen similarly treated with a weak solution of sulphite of soda. It is only necessary to hrush the solution over the surface of the fresh meat, and when dry it will leave the meat in such a state as to resist decay. Instead of covering the meat with the solution, it may be injected with it, as in the patents of Long (1834), Horsley (1847), Murdoch (1851), and others. After meat or fish is salted, it is frequently dried and smoked by exposing it in close chambers to the vapours of smouldering peat, wood, straw, &c., and in this manner it becomes impregnated with the dark-brown empyreu- matic oil of tho burning wood. The chief agent con- cerned in the preservation of food thus treated is the creosote of the empyreumatic oU, and this it is which gives the food a smoky flavour. A like effect may be produced hy dissolving the creosote of wood-tar ia vinegar, and brushing it over the salted joint. The creosote of coal-tar {carbolic acid) is also a powerful anti- septic, hut its flavour is not agreeahle, and therefore it is not used in the preservation of food ; although it is extensively employed, in the form of coal-tar, dead-oil, or creosote, in the preservation of wood, canvas, &c.; and the perfection of purity to which it is now brought by Dr. Grace Calvert and other manufacturers, encourage its use in medicine and surgery. Spirit of wine and vinegar are other preservative agents which owe their antiseptic power to their destructive action on infusorial life, and to their combining with the albuminous constituents of food. Cherry hrandy and pickles are good examples of this. Lastly, I may state that the fumes of burning sulphur {sul2)hurous acid) are very powerfully antiseptic; and many patents have been taken out for their employment in the preservatipn of food. In the spring of 1854, Laury obtained a patent for it, the gas being introduced into the vessel containing the substance to bo preserved. Later in the same year, Bellford received provisional protection for the use of sulphurous acid with about one-hundredth of its volume of hydrochloric acid—the object being to prevent the sulphurous acid combining ■with the alkaline salts of tho meat, and so giving it an unpleasant taste. The acids were to be used in solution, and the meat immersed in it for twenty-fom* hours. In the following year (1865) there wore three patents— those of Brooman, Demait, and Hands, for tho uso of the acid in a gaseous form; and in the specification of Demait it was directed that the substance should be pre- served by hanging it up in a chamber, and exposing it for a time to the action of the gas. Professor Gamgee has revived this process in a recent patent, and with certain modifications. He recommends, for example, that tho animal should be made to inhnlc carbonic oxide gas, and when it is nearly insensible, it should bo bled in the usual way. After tho carcase is dressed, it is to bo suspended in an air-tight chamber, which is to be exhausted of air, and then filled with carbonic oxide gas, to which a little sulphurous acid has been added. It is to remnin exposed to these gases for twenty-four or even forty-eight hours, and is then to be liung up in dry air, (ifter which it ia said that tho carcass will keep for many months, without perceptible change in taste or appear ance. The process has been tested by killing meat ii London, and sending it to New York ; and after tin lapse of from four to five months, the meat has been pro nounced good by a practical butcher. I am very mu( i inclined to think that the real preservative agent is th' sulphurous acid, and that the highly-poisonoua carbonii oxide gas might be advantageously excluded from th^ chamber. And now, in leaving this part of the subject, I canno refrain from saying that the history of these patents fo the preservation of food aflbrds very striking instam of the necessity for an amendment of our patent la\N - for not only is there a frequent disregard of all scientiii principles in the construction of the patents, but in man; cases there is also a total disregard, or else profound ignor ance, of what has already been done in the matter, lie petitions, therefore, occur again and again of the sami process, ncaiiy always imperfectly specified; and, oi the other hand, the most ridiculous propositions oftei assume an importance as if for no other object than tha of obstructing invention. Out of the 121 jmtents fo; the preservation of food, which I have had an opportunity of examining, there are hardly a dozen that can be re garded as either useful to the community or profitable tc the patentee. I come now to the last division of our subject—namely that which relates to the sale and use of unsound am adnlierated food ; and perhaps the most important of thi kind of food is bad meat—that is, meat which is unwhole some on account of putridity or disease. Food of thi description has always been a subject of legal prohibi tion. Among the Jews the prohibition dates from thii n time of Moses, who is supposed to have received froirv^ the Lord, during his sojourn upon Movmt Sinai, certair oral commandments respecting the slaughtering o animals for food, and the examination of their bodiei^ for disease. There is no account of these commandment in the written law, but they were evidently communi cated to the people of Israel by Moses, for he says thou shalt IdU of thy herd, and of thy flock, which th' Lord hath given thee, as I have commanded thee—(Deut.: chap, xii., v. 21). It is presumed, therefore, that thest- instructions were very specific, and they have beei practised by the Jews from that time until now. Tho Hebrew law is, that no flesh shall be eaten, except o<i animals that have been kQled and searched, or examineck by the officer {bodek) appointed for that purpose; anc the most precise rules are laid down for his guidance ii these matters. In fact, he is bound by very solemn obligations to declare of every animal that he kilWi whether the flesh is proper to bo eaten {cascr), or is unfif for food, by reason of its being diseased or torn {trcftijf This expression appears to have been derived from as ordinance of Moses, that no flesh should be eaten thatii torn in tlie field (Exodus, chap, xxii., v. 31); the wow torn {trefa or tcrcfa) being supposed, according to Hil traditions of Hebrew sages, to apply not only to animali torn in tho chase, or by wild beasts, or by thfc bungling act of tho butcher, but also to those afFecfc' with any disease that would shorten their lives ; and it is thought that such disease is always indicate* by the condition of tho lungs, the utmost care is take) by tho searcher or bodek in the examination of the? organs. His rules or instructions for this purpose ai very strict; but generally it may be said that he condemn as unlawful, or unfit for food, the llcsh of all animali in which tlie Imigs present the following appearances Certain deficiencies, excess, or displacement of the lohe? adhesions, or false membranes; tubercles, or nl containing matter or opaque water; discoloui.. wliich do not disappear when the lungs are inflatcu ulcers, holes, and abrasions letting air throu£,h then; consolidations th.at are impervious to air, and rottc nncs of tissue. Many of these are, no doubt, unim])oiian evidences of disease, and, therefore, although tlio lif s of such animals is rejected by the Jew, it is freely con sumcd by the Christian. The Jews, indeed, make a soi$