CHAPTER II.* 

 HEAT IN THE PRESERVATION OF FOOD PRODUCTS. 



HISTORICAL RESUME. 



The principle involved in the preservation of food by heat may be 

 said to have had its origin in the experiments of Spallanzani, who in 1765 

 boiled meat extract in hermetically sealed flasks for an hour, after which 

 treatment no change occurred in the material. An application of this 

 principle was suggested as early as 1782 by the Swedish chemist, Scheele, 

 who advised the exposure of vinegar in bottles to the temperature of boil- 

 ing water in order to effect its preservation. Some years later the principle 

 was applied to the conservation of food by a French confectioner, Nicholas 

 Appert, who in 1811 published an exhaustive treatise on "The Art of 

 Preserving Animal and Vegetable Substances." His method was to 

 enclose the food in a glass jar which was then corked tightly, and placed 

 in boiling water, the length of time of heating varying with the article 

 treated. 



In 1810 Peter Durand secured a patent from the English government 

 for the preservation of fruits, vegetables and fish in hermetically sealed 

 tin and glass cans. He did not claim to be the discoverer of the process, 

 but said it had been communicated to him by a "foreigner residing abroad." 

 Although the secret of the process was jealously guarded, the employees 

 of different establishments became familiar with its essentials, and in 

 this manner the industry found its way to America. One of the first 

 to introduce the process was Ezra Daggett, who, with his son-in-law 

 Thomas Kensett, in 1819 engaged in the manufacture of hermetically 

 sealed goods, the principal foods packed being salmon, lobsters, and 

 oysters. In 1820, William Underwood and Charles Mitchell, emigrant 

 employees from a canning factory in England, opened a factory in Boston 

 where they canned plums, quinces, cranberries and currants. 



In the earliest days of canning, glass jars were used exclusively, but 

 were gradually abandoned as it was found that they could not readily 



* Prepared by S. F. Edwards. 



