MEATS, PRESERVED 223 



kin, Hall, and Gamble wore able to overcome the primary difficulties of this invention, 

 and produce provisions successfully preserved in tin-plate vessels. 



The process of Appert certainly does not depend upon the exclusion of oxygen 

 from the provisions he preserved, nor is this principle included in the improved process 

 still practised by the firm of Gamble. Appert seems to have had a doubt as to the 

 sufficiency of the oxygen theory, for he tells us that, ' fire has a peculiar property, not 

 only of changing the combination of the constituent parts of vegetable and animal pro- 

 ductions, but also of retarding, for many years at least, if not of destroying altogether, 

 the natural tendency of these same products to decomposition.' And this opinion is con- 

 firmed from many startling facts, which cannot be reconciled to the supposition that 

 oxygen is the sole or even principal agent of decomposition. Thus milk, which has been 

 merely scalded, will keep much longer from the effects of this process, even though freely 

 exposed to, or purposely impregnated with, oxygen gas. Now the method of Appert, as 

 improved by Gamble, is to render the albumen of the meat or the vegetable insoluble, 

 and therefore scarcely if at all, susceptible of the action of atmospheric oxygen. By 

 this means the total exclusion of air from the tin cases is rendered unnecessary, for 

 even if a small quantity of air remain in the case, it will exert no more influence 

 than happens to a piece of coagulated albumen, or hard boiled white-of-egg, which, 

 as is well known, may be exposed to the air for years without sensible alteration, 

 though in its uncoagulated state it immediately putrefies. It appears, therefore, 

 that the essential characteristics of Gamble's process may be referred not to the 

 exclusion of air, but to the thorough coagulation of the albumen. The heat employed 

 also destroys all organic germs that may be present, and thus prevents their develop- 

 ment. In this process, the meat, more or less cooked, is placed, with a quantity of 

 gravy, in a tin vessel, capable of being hermetically sealed with solder ; it is then 

 heated, for some time, in a bath of muriate of lime, and the aperture neatly soldered 

 up. After this it is again exposed to the action of the heated bath for a period, which 

 varies with the size and nature of the contents of the vessels ; and to prove that this 

 latter operation is really the most important of the whole, it sometimes happens that 

 cases which have begun to decompose are opened, resoldered, and again submitted to the 

 muriate-of-lime bath, with the most perfect success, as regards the ultimate result. 



Although by no means free from occasional failures and certainly requiring im- 

 provement, the system of Gamble has in practice worked well ; and provisions have 

 been kept in this way, for a long period of years, without the slightest alteration 

 in their particular qualities. 



Mr. Goldner, some few years ago, adopted the idea originally conceived by Sir 

 Humphry Davy, of enclosing cooked provisions in a complete vacuum. For this 

 purpose the provisions, slightly cooked on the surface, were enclosed in canisters, 

 similar to those of Gamble, but stronger, and provided with a small opening in the 

 cover. At this moment a slight condensation was effected by the application of a 

 cold and damp rag or sponge, and simultaneously with this the small opening was 

 soldered up. In theory, nothing could seem better adapted to insure success ; but, 

 the practical working of the invention afforded any thing but a satisfactory result. Nor 

 is there much difficulty in conceiving how this may arise, as in the first place the ap- 

 plication of a sudden heat to non-conducting materials, is almost certain to give rise 

 to that peculiar condition by which the interior of the meat will be as thoroughly 

 protected from the effect of heat as if no heat were applied. Hence, even though 

 steam in abundance may issue from the small opening in the cover, this is no proof 

 that the meat in the centre of the vessel is even warmed ; and still less does it 

 warrent the supposition that the soluble albumen is thoroughly coagulated; and 

 without which, as we have stated, preservation is scarcely possible. 



Redwootfs Process. This process, invented by Professor Eedwood, consists in 

 the immersion of fresh meat in melted paraffin, at a temperature of 240 Fahr. 

 (115 Centigrade), for a sufficient time to -effect a concentration of the juices of the 

 meat and the complete expulsion of air ; after which the meat, in its condensed state, 

 is covered with an external coating of paraffin, by which air is excluded and de- 

 composition prevented. 



The concentration of the juices may thus be carried to any required extent. If 

 the meat is to be kept in hot climates its weight should be reduced by evaporation to 

 about one-half, in which state it will contain all the nutriment of twice its weight of 

 fresh meat, the portion driven off by evaporation consisting only of water. Thus 

 prepared it will be fully cooked (by the heat applied in the process), and it may be 

 eaten withoxit further preparation, but it will also be applicable for the preparation 

 of a variety of made-dishes, including stews, hashes, soups, gravies, etc. For cold 

 climates a less amount of heating and concentration will suffice, so that the meat 

 may retain its original juicy condition, and, when further cooked, present tho 

 appearance, and possess all the characters, of fresh unpreserved meat. 



