. Cyclopedia of farm crops. Farm produce; Agriculture. THE COMMERCIAL CANNING INDUSTRY 169 temperature of 100° Centigrade (212° F.) being thereby obtained. (2) The chemical bath. This consists of a strong solutionof some salt, gen- erally calcium chlorid, because of its great sol- ubility. The boiling point of the solution being much higher than that of water, higher temper- atures may be reached by its use than with the ordinary water bath, and consequently a shorter time is required to bring about sterilization. This method was first em- ployed in this country about 1863, but was not a succe
. Cyclopedia of farm crops. Farm produce; Agriculture. THE COMMERCIAL CANNING INDUSTRY 169 temperature of 100° Centigrade (212° F.) being thereby obtained. (2) The chemical bath. This consists of a strong solutionof some salt, gen- erally calcium chlorid, because of its great sol- ubility. The boiling point of the solution being much higher than that of water, higher temper- atures may be reached by its use than with the ordinary water bath, and consequently a shorter time is required to bring about sterilization. This method was first em- ployed in this country about 1863, but was not a success because the cans of that time were not strong enough to withstand the pressure generated within. The method of use is the same as with the water are boiled for a certain. Fig. 248. A commercial com cooker. bath, i. e., the filled cans definite period. (3) Steam under pressure. This method of steril- ization was introduced about 1870. The tempera- ture in this case may be varied by control of steam pressure. The steam being confined in the retorts, of course the pressure is equal within and without the cans ; thus, unless the outside pres- sure is removed suddenly, the strain on the cans is not great and loss from bursting is small. Most of the modern cans, however, are sutticiently strong to withstand sudden changes without injury. There are two modifications of the retort, known as the "wet retort" and the "dry ; In the former, the kettle is filled with water and steam under pressure blown in, so that the boiling-point of the water is much raised owing to the increased pressure. These kettles are generally cylindrical and are placed in a vertical position, with a heavy lid on the upper end. When in use, this lid is fast- ened down by means of heavy bolts. The kettles are generally provided with three valves,— an intake valve for steam at the bottom, an outlet for water at the bottom and an exhaust valve for steam in the lid. Although spoken of
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