Briefly, the process of preserving meat in air-tight packages con- 

 sists in packing it, after the removal of the bones and subdivision 

 into bits of proper size, as tightly as possible into the packages which 

 have been prepared for it, which are usually made of tin. These 

 packages are securely sealed, with the exception of a small opening, 

 and in this condition are subjected to a temperature of about 220 

 until the contents of the packages are thoroughly sterilized ; in other 

 words, until the organisms capable of effecting decay have been 

 destroyed. It is customary in the case of meat to pour into the can, 

 after packing with the meat, some gelatin or animal fat, which fills 

 all the interstices not occupied by the pieces of meat, so that no gas of 

 any kind is left within the can, except the vapor of water produced 

 by the heat of sterilization. While the can is still hot the open- 

 ing which has been left is securely sealed. On cooling, the vapor of 

 water which the can contained is condensed and the contents are left 

 out of contact with the air and in a thoroughly sterilized state. In 

 this condition the contents of the package keep indefinitely. If by 

 any means the sterilization be not complete, or if the package be inse- 

 curely sealed ' so that organisms can be introduced from the air, the 

 process of decay will begin after a time, gases will be generated, 

 and the can when opened will show the effect of the stress of the gas 

 within by the escape thereof through the aperture which is first 

 made. The contents of such a package will be found more or less 

 decayed and unfit for use. 



In the case of certain meats, such as roast beef and corned beef, 

 it is the custom to cook them before they are chopped and put into 

 the can. The process of cooking, as is well known, does not impair 

 the digestibility of the food. If meat be boiled in water previous to 

 preserving in sealed packages, a portion of the fat may- be removed 

 and also some of the soluble nitrogenous compounds which all meats 

 contain. The most important nitrogenous compounds which may 

 be removed by the boiling of the meat are glutin, carnin, kreatin, 

 kreatinin, and sarkin. All these are bodies which are very rich in 

 nitrogen ; they are not true proteid bodies, but are known as ' ' flesh 

 bases." These are the bodies which exist chiefly in meat extracts. 

 These bodies are not so nutritious as the insoluble nitrogenous bodies 

 of meat and their abstraction therefrom does not tend to diminish 

 but rather to increase the food value of the meat. 



Animal fats when removed from other animal tissues are not 

 easily decomposed, and preserve their freshness without the addi- 

 tion of any preserving agent, or without being placed in air-tight 

 packages, for a greater or less length of time. In the preserving of 

 meats, therefore, some of the fatty tissues are removed and only 

 small portions of animal fat, comparatively, are found in the pack- 

 ages. Preserved meat then consists chiefly of the insoluble, nitro- 



