196 BACTERIA, YEASTS, AND MOLDS 



Hermetical sealing, which will prevent all subsequent 

 access of air, is extremely easy to accomplish and is thor- 

 oughly effective. The material must be sealed in some 

 proper receptacle while still hot from the boiling, for it is 

 at this time sterile and, if sealed at once, has no opportunity 

 of becoming inoculated with more bacteria. 



The devices for hermetical sealing are numerous. In 

 earlier days the housewife employed ordinary bottles, which 

 were filled with the material, then plugged tightly with corks, 



^ — , and sealed with rosin 



( t l ^ ^^^Tllllff T ^ ~^ ^"^ something of the 



* ^ — ~ —^ 5 ^ ^^^ invention of the 



ij[^-~ ^ s ::^^::^^^-^-^^ ' modern fruit jar with 



/ , ( - — " \. its rubber ring and con- 



■ — . J venient top has done 



Fig. 65. The top of a common fruit jar; u, away with all SUch 

 is the rubber ring upon which the success ^.^^^j^ devices. The 

 of the sealing is dependent. 



fruit jar with its vari- 

 ously devised top (Fig. 65) is a perfectly effectual means of 

 excluding air and hence for keeping out all microorganisms. 

 The significant feature of these fruit jars is the rubber ring 

 a, which is clamped tightly upon a flat ledge on the jar c 

 by means of the cover b, so made that heavy pressure can 

 be exerted upon the rubber. This pressure upon the rubber 

 effectually excludes all air and all bacteria. Fresh rubber 

 rings should be used each time the jar is filled, since the 

 efficiency of the sealing depends upon the softness and elas- 

 ticity of the rubber; if this gets hard, as it will in a few 

 months, the sealing will not be as effectual. Of course com- 

 plete sterilization of the jar must be assured. In the cold-pack 



