Miscellaneous Papers. \:U 



SOME expp:kiments with the mason fruit jar. 



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IN the following brief discussion of the Mason fruit jar I 

 have brought together some data that have been obtained 

 not only in the Kansas food laboratory, but also in the Indiana 

 state food laboratory. 



We will take up first the question of volume. For years the 

 housewife has considered Mason fruit jars as standards of 

 \ olume. She has sent quart jars to the grocery store for vine- 

 gar, molasses and milk, thinking that in this way she was out- 

 witting the wily, short-measuring grocer and obtaining a true 

 (luart. But investigation of the volume discloses the fact that 

 the quart size is almost a half pint short measure, and the 

 larger sizes short in proportion. It is impossible to estimate 

 the total loss to the consumer that his uniform short volume of 

 -Mason jars has caused. 



The original cover of the Mason jar was a zinc cap which 

 screwed on, and which when used in connection with a rubber 

 ring gave an air-tight seal. 



It was found that this zinc cap was acted upon by the con- 

 tents of the jar, and in many cases holes were eaten through 

 the cap, the metal going into solution. We have at the Univer- 

 sity some jars covered with such zinc caps, which at one time 

 contained vinegar. The caps are badly corroded and contain 

 many holes. Analysis of the contents showed a high zinc 

 eontent. An improvement over the plain zinc cap was one 

 made with a glass or porcelain lining, and this is the type most 

 commonly found on the market to-day. In this type only a 

 small amount of metal comes in contact with the liquid. A 

 later type is so arranged that the closure is made by placing 

 the rubber ring on the edge of the glass neck in such a way 

 that the closure is made not with the edge of the cap, but by 

 the inside glass lining. This type is the White Crown. 



E.xperiments were carried on at the Indiana station to deter- 

 mine the relative merits of the old and new caps. Seven jars 

 were tilled, in duplicate, with acid solutions of the following 

 strengths: \ and 1 per cent phosphoric acid, .'. and 1 per cent 

 acetic acid. .' per cent tartaric acid, and ' and 1 per cent nitric 



