10 



BULLETIN 1022, TJ. S. DEPARTMENT OF AGRICULTURE. 



values as affecting canning operations is therefore important for 

 the present work; and while it is not possible to calculate by 

 formulas the actual results which will be obtained in practice, be- 

 cause of other variable factors, the theoretical pressures and vacuums 

 falling within the range of the present experiments serve as a back- 



















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ERATURE IN DEGREES CENTIGRADE 



Fig. 3. — Theoretical maximum-pressure 

 curves for a nonexpansible can con- 

 taining air and sufficient water to give 

 saturation, when sealed at different 

 uniform temperatures and processed in 

 the retort at 100°, 109°, 116°, and 

 121° C. Calculations are made on the 

 basis of mean barometric pressure. 

 Curve for can processed : A, At 100° 

 C ; B, at 109° C. ; G, at 116° C. ; D, 

 at 121° C. 





















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Fig. 4. — Experimental time-pres- 

 sure curves for No. 2 cans 

 containing 550 c. c. of dis- 

 tilled water sealed at uni- 

 form temperatures and proc- 

 essed for 1 hour. Curve for 

 can sealed: A, At 20° C. 

 and processed at 100° C. ; 

 a, at 20° C and processed at 

 116° C ; a', at 20° C. and 

 processed at 121° C. ; B, at 

 70° C. and processed at 100° 

 C. ; h, at 70° C. and proc- 

 essed at 116° C. ; &', at 70° 

 C. and processed at 121° C. ; 

 C. at 80° C. and processed 

 at 100° C. ; c, at 80° C. and 

 processed at 116° C. ; c', at 

 80° C. and processed at 121° 

 C. 



ground for the work and as a guide in the interpretation of the 

 experimental results. 



Theoretical pressure curves. — In figure 3 are shown the theo- 

 retical maximum-pressure curves for a nonexpansible can contain- 

 ing air and a sufficient quantity of water to give saturation, when 



