TEMPERATURE CHANGES IN CANNING FRUITS AND VEGETABLES. 



at the upper end to form a funnel-shaped depression to allow suit- 

 able packing, and the cap screws down to hold this tightly about the 

 thermometer and make the seal perfect. In practice, this fitting is 

 rarely removed from the retort cover, the can being unscrewed from 

 beneath and the thermometer removed by unscrewing the cap. 



It will be seen that this apparatus is as well suited for use with 

 thermocouples as with thermometers. 



A modification of A is shown at B, differing from it in that the 

 fitting may be soldered directly to an ordinary hole-and-cap can. 



For work with glass jars, those of the Mason screw-top type were 

 used. These were attached to the fitting A (fig. 2) by removing the 



(Vtrfiul Section) 



(Vttticil 

 Sect ion) 



Fig. 2.— Details of the special fitting to which the can is attached for the test : A, The 

 original form ; B, a modification of A, differing from it in that the fitting may be 

 soldered directly to an ordinary hole-and-cap can. 



porcelain in the top, cutting a hole in the metal large enough to re- 

 ceive the portion of the fitting below the shoulder, and securing it 

 firmly to the fitting by means of a suitable gasket and nut. The jar 

 could then be placed in position for the test by simply screwing it 

 into the top. 



This apparatus as described may be constructed in any well- 

 equipped machine shop at small expense. It is easy to operate, re- 

 quires no special training for carrying out the tests beyond that pos- 

 sessed by anyone familiar with canning operations, and is sufficiently 

 accurate for all practical needs. Tests made by its use have been 

 carefully checked with thermocouples, and the differences observed in 

 the results have been too small to be of practical significance. Any- 

 44900°— 21 2 



