Hawke's Bay Times. THURSDAY, FEBRUARY 20, 1868. MEAT-PRESERVING FOR EXPORTATION.

Hawke's Bay Times, Volume XIII, Issue 553, 20 February 1868, Page 2

Hawke's Bay Times.

THURSDAY, FEBRUARY 20, 1868. MEAT-PRESERVING FOR EXPORTATION.

Nulliu) addictus jurare in verba magisfri.

UNQUES'nois’AJiLY cue of the greatest problems of the present age is that of so treating the surplus stock of the Colonies that whole carcasses and joints may be presented to the British comsumer in a state as nearly approaching that of the fresh home-killed I beast us possible. It is a problem, j too, which no one at all conversant i with the resources of chemistry would pronounce beyond the range of possibility, or even economical probability, and we hesitate not to say that if the rewards offered by several Governments for the discovery of gold-fields bad been offered for the discovery of such a process, the problem would have long since been satisfactorily solved.

For many years past a process of preserving cooked meats in air-tight tins has been practised with a great amount of success—in fact, amongst the treasures rescued from the wreck of the Royal George iu 1834, were some tins of this description, the contents of which, though subjected to submersion during - a whole generation, were yet sweet and good—the preservation in such cases depending on the complete exclusion of atmospheric air, without the presence of which fermentation cannot take place. The preserving of food by this process has become an important branch of manufacturing industry, and it produces an | excellent article of diet fur long sea-- | vo many other circtnnslanj cos, but it has not become, nor wiii st over become, a staple article of food with the “ Britisher.” It makes beyond question a good mess, but this is exactly what Julia Bull does not want day by Jay. He must have his joint of meat, and this he will not ■-xchange for any number of tins of

the preserved article. 'lhe well-established conditions of fermentation or decay (for the terms are convertible) are, first, fermentable milter; second, some active ferment; tain!, the atmospheric air ; fourth, bture ; and, fifth, a sufficient term nerature, Any one of these being absent the fermentation is stayed, in the case under consideration the ilesh is the fermentable matter, and it contains within itself an active ferment. There then remains the othor three conditions, either of which, being abstracted, solves the problem. First, atmospheric air. The potted moats to which allusion has been made above are preserved in this way. The flesh, being cut in small pieces* is placed in tin canisters, which are soldered down, a small hole only being left in the top for the escape of steam. Those are then subjected to a high degree of heat for a period more or less prolonged, which causes a great production of steam. This, rushing out of the small aperture, carries out with it all the atmospheric air, its place being supplied with aqueous vapor. When this is judged to be accomplished a drop of solder is melted over the hole and suddenly cooled, the entrance of the air being effectually stopped, and so the process of fermentation is stayed. Next, the presence of moisture has been said to be a condition. The ap« plication of this principle of counteracting tiiis condition is soon xu the case of dried provisions of various kinds, which has a somewhat extensive and useful application, especially when used together with an antiseptic ; but it does not seem calculated to answer

jthe desired end of superseding the ijoint of butcher’s meat. Lastly, the temperature. It has long been known that no fermentation takes place at or below the tempera tore of the freezing point of water, and this knowledge has been turned to account in the packing of nrovisions in ice for transmission to distant parts, the only points to be attended to being the freshness of the article when! packed, and the prevention of a rise of temperature. So certainly successful is this principle that no limit whatever seems to he assignable to its application. It is known, in fact, that the carcasses of a pre-Adamic era have been effectually preserved in ice by nature down to our own day—such carcasses being occasionally brought down by glaciers from high northern latitudes, and being useable and used as food by dogs and men, after having been dead fur thousands of years, being preserved from decay all during that period of time by the exceedingly low temperature of the polar regions. What was wanted, then, for the solution of the great problem was the discovery of a method by which the freshly-killed sheep and oxen of the Australian Colonies could be at once frozen and kept in that stale daring their transmission to the home market, this transmission implying of course a voyage through the tropical regions, and extending over a period of three or four months.

Chemistry is at no loss for means tor the production of changes of temperature ; scarcely any operation can be performed without a disturbance ot that description—evaporations and solutions in general being usually attended with a reduction of temperature, while condensation and crystaliiz ition, are as usually attended by the evolution of heat. A thermometer, for instance, taken from witer c-i any temperature, alu-ays descends at first from the evaporation of moisture from its surface, and, as a familiar instance, a person's hand, being dipped in water and being afterwards moved rapidly through the air, will experience a decided sensation of cold. Water, too, may be easily frozen in a bottle by keeping the exterior surfacemoistened with sulphuric ether—the heat necessary for its evaporation being obtained from the water, speedily reduces it to the state of ice.

The following parlor experiment, being at once easy, interesting, and instructive, may be performed b} r any person desiring to have a practical il lustration of the remarkable facility with which ice may be procured at any time, and it will well repay the trouble attending its performance. Take two vessels of any convenient kind, one being smaller and capable of standing inside the other, leading| a space between—say, two cylinders i of tin, one of 3iu. and the other of| l|in. in diameter, and as high as convenient; nearly fill the smaller one with water, and stand it in the larger during the solution of a mixture of equal parts of carbonate of soda and nitrate of ammonia, covering the whole with a woollen cloth during the operation. Four ounces of each of the above salts will freeze XOoz. of water during their solution, in two or three hours, and the cylinder of ice may be turned out solid on the table. The

outer vessel should be well protected from the warmth of the room by a coating of flannel or wool. One of the most beautiful experiments in the whole range of chemistry is the freezing of carbonic acid gas. This gas is not permanently elastic, but can by pressure on itself be com- | pressed to the liquid state, and its

freezing may be accomplished as follows—By means of a powerful condensing syringe force a large quantify of carbonic acid gas into a strong glass vessel provided with a stopcock at its upper part ; as it is condensed in this vessel it will be seen to collect at the bottom like oil. If the stop cock be then opened to give it vent it will resume its gaseous form, rushing out with violence, absorbing even its own sensible heat, and producing cold so intense that itself freezes and falls in the form of a beautiful snow. A phenomenon of a similar character may be produced with ammonia. In its dry state it exists as a gas, and like the above it may be by pressure forced to assume the liquid state, absorbing a vast amount of heat on resuming its gaseous condition, and this properly it is that renders it available for the production of artificial cold, as is exemplified in the process of the “ ice company” of a neighboring colony. Tiiis process, as we understand it from description in the Sydney papers, we shall endeavor to explain to the general reader in a very few words— The apparatus consists of a “ meatreceiver,” analogous in its use to the smaller of the two vessels used in our parlor experineut, a “ liquid gas receiver,” corresponding to the strong glass vessel in which we liquified the carbonic acid gas, and a “re-absorber.” the meat receiver is a capacious cava surrounded by an air-tight chamber, which communicates with the liquified gas and also with the re-absorber by means of stop-cocks. A small quantity cf the liquified gas being passed into the air-l'ght chamber and the stopcock closed, it is in its highly com-

pressed state in contact with the exterior of the meat receiver, and really fur active service. Ou communication being opened with the re absorber the gas expaniiug rushes violently into it, carrying off with it the heat from the contents of the meat receiver. Tiie reibsorber contains water which rapidly absorbs the gas, and becomes a sedation of ammonia wffich it is ready to give off for condensation as before.

The above is sufficient to give an idea af the means used for producing the exceedingly low' temperature of the meat receiver, but the beautiful arrangement by means of which the above circulation is effected, and the volatilised atumouia is deprived of its watery vapor (desiccated) and rendered fit for compression, and the water condensed from it carried by a second circulatory system, back from the desiccator to the re-absorber, to be again charged with the gas it has just before been parted from, involves details which require the aid of illustrative diagram's to explain. It is sufficient to say that as in the grand operations of nature, there is a continued circula-

tion <•{ the same elements, which are combined and d-composed, volatilised and condensed, the motive power being heat first applied to volatilise the ammonia in the separator. From what has been said above it will he seen that the principle of the invention—the compression of an elastic fluid artificially, in order that in its re-espaasiou it may absorb heat from contiguous bodies—is not by any means new, nor of limited application, that a similar result can be effected by tho use of ether, carbonic acid gas, or any of a numerous class of bodies that fulfil the requisite conditions. In the present case ammonia was chosen on account of its affinity for water, which doubtless gives it an advantage ; still we regard it but as the first of a series of applications of a well established principle, in the successjrf tohich we have everv confidence, "y r a