Reynoso's.—The meat is subjected to the action of compressed nitrogen, carbonic oxide, &c. After being kept in this state for 40 days, the freshness has been so maintained that blood has flowed from the joints.
Riehardsen's.—Dr. Richardson made some teat experiments with meat treated with various antiseptios, under a temperature varying from 7° (45° F.) to 43° (110° F.), for a period of 75 days. The results may be summarized thus :—Methylene : preservation, good ; colour, imperfect. Methylal : faint taint of decomposition. Cyanogen : preservation, excellent; colour, perfect ; structure, firm. Sulphurous acid : some tainted; colour, dark. Sulphurous acid and lime-juice : some tainted ; colour, indifferent. Sulphurous acid and glucose : some tainted; structure, dense. Nitrate of methyl : preservation, good ; colour, yellowish ; structure, firm. Formates : entirely fresh, and excellent in colour.
Estor'e.—Thie consists in treatment with sulphurous acid and chlorine in succession.
Gamgee's.—The animals are killed by inhaling carbonic acid, &c., and the carcases are kept in an atmosphere of carbonic or sulphurous acid. This does not prevent decomposition where bruises exist.
Medlook and Bailey's.—The meat is immersed in a solution composed of equal parts of water and bisulphite of lime, of 1'05 sp. gr. It acquires no unpleasant flavour. This is one of the most successful of the antiseptic processes.
Pelletier's.—The meat is covered with a costing of gum, then immersed in acetate of alumina, then in solution of gelatine, allowing the whole to dry on the surface. The antiseptic acetate of alumina forms an insoluble compound with the gelatine.
Pagliare's.—Gum benzoin ie boiled in a solution of alum. The meat is immersed in this compound, and excess moisture is driven off by a current of hot air, leaving the antiseptic on the meat.
Jones and Trevethick's.—Tbe meat is put into tin canisters, which are hermetically closed, except two holes in the lid. These are plunged into a vessel containing water, and after the air has been exhausted by an air-pump through one hole, sulphurous acid gas is admitted through the second, and this alternation is continued till all the air is out. The sulphurous gas is then replaced by nitrogen, and the holes are closed.
Exclusion of Air.—As the presence of oxygen seems to be essential to the existence of decompo sition, many plane for the preservation of meat have been based upon tho exclusion of air from it. By far the most important are the numerous modifications of cooking in air-tight cans, called " canning," which have been conducted for years with great success. The heat of the cooking destroys any microscopic germs, if such be present, and, at the same time, expels all air from the receptacle and from the substance itself. The preservation is complete, but over-cooking is
unavoidable, and the meat is rendered soft, fibrous, and insipid.
" Canning."—There are three chief modifications of the canning process :—(1)" Aberdeen "; (2) " steam-retort" ; (3) "chloride calcium bath." The Aberdeen process probably originated with Appert, whose plan was brought into use during the Crimean war. The meat is placed in vessels nearly closed ; these are then put into a close boiler, and the heat is raised to 112° (231° F.). After about 3 hours' 000king, the vessels are hermetically sealed. McCall's improvement upon this consists in the addition of a little sulphite of soda. Jones' improvement lies in the fact that the water is first driven off at 110° (230° F.) in vacua, and the heat is then raised to, and kept at, 132° (270° F.). The special feature is the vacuum, all the oxygen being extracted by means of tubes connecting the tine with the vacuum-chamber ; this greatly reduces the time. By the steam-retort plan, the meat is canned up, leaving a pin-hole, and the cans are put into a retort under steam at 110° (230° F.), and kept there for 1i-2 hours ; they are then taken out, and the pin-holes are soldered up while steam is issuing from them. The cans are again steamed at 116° (240° F.), and cooled. The object of the chloride of calcium bath is to obtain a higher temperature. The raw meat is put into caul having a pin-hole, as before. The cans are placed for half their depth in a solution of chloride of calcium, boiling at 127°-132° (260°-270° F.). The beat is gradually raised from (180° F.) to 110° (230° F.), and the steam is allowed to blow off for 4 hours, during which time the meat is being cooked. The holes are then closed by a drop of solder, the heat is raised to 127°-132° F.) for lj hour, and the cans are withdrawn and cooled. Ritchie's deviation from this consists chiefly in desiccating the meat first in an oven at 204°-216° (400°-420° F.), and then packing it in cans, with the addition of meat jelly to create steam, before subjection to the chloride of calcium bath.
Naylor's process.—The meat is cooked, and then packed in cases, and covered with stearine (tallow).
Redwood's process.—The meat is immersed in melted paraffin at 115° (240° F.), to concentrate the juices, and expel the air. Thus condensed, the meat is covered with a coating of paraffin. Before use, it is placed in boiling water, which removes the paraffin ; it can only he used in its cold state, not hearing re-cooking.