. Bulletin of the Department of Agriculture. Agriculture; Agriculture. s BULLETIN 1022, U. S. DEPARTMENT OE AGRICULTURE. conductivity of copper at about , of brass at about , and of glass at , the chances of error from heat conduction are hun- dreds of times greater with this thermocouple than with the ther- mometer. It must be borne in mind that in experimental work with canned foods small inaccuracies are of minor importance. Because of the differences in the con- sistency of the material, of difficulty in prepar- ing uniform packs, of difficulty in adjusting closely the ret
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. s BULLETIN 1022, U. S. DEPARTMENT OE AGRICULTURE. conductivity of copper at about , of brass at about , and of glass at , the chances of error from heat conduction are hun- dreds of times greater with this thermocouple than with the ther- mometer. It must be borne in mind that in experimental work with canned foods small inaccuracies are of minor importance. Because of the differences in the con- sistency of the material, of difficulty in prepar- ing uniform packs, of difficulty in adjusting closely the retort tem- peratures throughout the entire process, and of other factors, it is practically impossible to check time-tempera- ture curves closer than ° C, and it is doubt- ful whether a difference of ° C, or perhaps even more with mate- rials of this kind, is of any practical signifi- cance. PRACTICAL VACUUM TESTS. In an attempt to de- termine the optimum temperature for sealing, cans of various mate- rials were prepared in lots which were sealed at the temperatures of 20°, 50°, 60°, 70°, 80°, 90°, and 100° C, respec- tively. In some cases, instead of this proce- Fig. 2,-Apparatus used in the concussion tests. ^^ the C|mg ^^ ex_ hausted for two, four, or six minutes and then sealed. In each case the lots were divided and one half were tested for vacuum with a common Young's vacuum gauge, and the remainder were subjected to concussion tests to learn to what extent the vacuum affects the denting and collapsing of cans in ordinary Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States. Dept. of Agriculture. [Washington, D. C. ?] : The Dept. : Supt. of Docs. , G. P. O.
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