TEMPEBATUKE CHANGES, ETC., DURING CANNING OPERATIONS. 13 



Table 1. — Maximum-pressure tests with No. 3 tin cans containing 100 c. c. and 

 950 c. c. of distilled icater. 



Temperatures 

 (°C.). 



100 c. c. water. 



950 c. c. water. 



Temperatures 

 (°C). 



100 c. c. water. 



950 c. c. water. 



Sealing. 



Proc- 

 essing. 



Barom- 

 eter. 



Pres- 

 sure per 

 square 



inch. 



Barom- 

 eter. 



Pres- 

 sureper 

 square 



inch. 



Sealing. 



Proc- 

 essing. 



Barom- 

 eter. 



Pres- 

 sure per 

 square 



inch. 



Barom- 

 eter. 



Pres- 

 sure per 

 square 



inch. 



20 



50..!.... 



f 100 



109 



i 116 



I 121 



f 100 



109 



i 116 



I 121 



f 100 



109 



i 116 



{ 121 



29.92 

 29.92 

 29.92 

 29.92 



30.08 

 30.08 

 30.08 

 30.08 



30.11 

 30.11 

 30.11 

 30.11 



Lbs. 



17.06 



22.70 



28.23 



32.89 



13.87 

 19.51 

 25.10 

 29.60 



12.45 

 18.04 

 23.50 

 28.10 



30.18 

 30.18 

 30.18 

 30.18 



30.15 

 30.15 

 30.15 

 30.15 



Lbs. 



14.60 

 20.25 

 25.40 

 29.52 



10.99 

 16.36 



21.44 

 25.02 



70 



80 



90 



f 100 



109 



i 116 



I 121 



f 100 



109 



i 116 



I 121 



f 100 



109 



1 116 



I 121 



30.05 

 30.05 

 30.05 

 30.05 



29.95 

 29.95 

 29.95 

 29.95 



29.92 

 29.92 

 29.92 

 29.92 



Lbs. 



10.67 

 16.26 

 21.78 

 26.26 



7.97 

 13.37 

 18.95 

 23. 50 



4.66 

 10.12 

 15.46 

 20.06 



30.18 

 30.18 

 30.18 

 30.18 



30.16 

 30.16 

 30.16 

 30.16 



30.05 

 30.05 

 30.05 

 30. 05 



Lbs. 



9.88 

 15. 49 

 20.74 

 24.91 



7.30 

 12.70 

 17.64 

 21.66 



4.41 









9.51 









14. 36 









17.79 











Too much importance, of course, should not be attached to one set 

 of figures, as results with individual cans vary somewhat, but the 

 outstanding features shown here have been confirmed by repeated 

 experiments, and the figures presented closely approach the average. 



Leading facts disclosed. — From all these tests the following facts 

 seem clear : 



(1) With water the pressures developed are always below the 

 theoretical (that with some food materials this does not hold in all 

 cases will be shown later). 



(2) The higher the retort temperature, the greater the variation 

 from the theoretical pressures. 



(3) The higher the initial temperature, the nearer to the theoreti- 

 cal does the pressure come. 



(4) The larger cans show a somewhat greater divergence from the 

 theoretical values than the smaller. 



(5) With water, the smaller the head space the less the experi- 

 mental pressures obtained. The fact that with water the smaller the 

 head space the less the experimental pressures obtained is likewise 

 borne out by experiments with No. 2 cans, using 50 and 550 c. c. of 

 water, the tabulation of the results of which is omitted for lack of 

 space. 



Influence of head, space.-. — With cans entirely filled and sealed at 

 any temperature below 100° C. the experimental pressures have been 

 found less than where a head space was allowed. This is explained, 

 of course, by the fact that under these conditions the prime factors 

 operating are vapor pressure and expansion of the water, whereas 

 when a head space is allowed the air pressure also contributes to the 



