Quantities of Tin and Hudrogen in "Springers." 165 



toes, greens, tomatoes, peaches, apples, hominy, beets, kraut, 

 asparagus, blackberries, raspberries, strawberries and cherries. 

 The tables appended contain the results obtained. For the 

 sake of ready comparison the tin is expressed in milligrams 

 per kilogram of food and the gases as cubic centimeters per 

 kilogram. 



The term "excess gas," as used in the tables, is to be in- 

 terpreted as meaning the amount of gas given off by the can 

 during the equalization of pressure. 



The volume of gas remaining in the can was obtained from 

 measurements of the total volume of the can and the volume of 

 the food contents. 



The tin determinations were made by the iodine titration 

 method, as outlined by H. A. Baker in his article "Special 

 Adaptation of Iodine Titration Methods for the Estimation of 

 Tin, Especially in Connection with Determinations of 'Salts of 

 Tin' in Canned Foods," published in "Original Communica- 

 tions, Congress of Applied Chemistry." 



An examination of the table will show that : 



1. In the majority of cases the gases present were hydro- 

 gen, carbon dioxide, and nitrogen (the inactive residual gas 

 being considered as nitrogen). The presence of these three 

 gases alone, coupled with the fact that the condition of the 

 food in 90 percent of the samples was good, judged by the 

 taste, smell and appearance, suggests that the samples exam- 

 ined were "springers." 



2. No definite relation exists between the amounts of tin 

 and hydrogen. 



3. The hydrogen in nearly all cases is a small fraction of 

 the amount which the tin present is capable of liberating by 

 interaction with acids. 



These facts suggest that considerable tin is corroded by 

 agents other than acids. 



4. The amounts of carbon dioxide present in the majority 

 of samples are relatively large. Whether these amounts are 

 formed during processing, or subsequently as a result of fer- 

 mentation, has not been determined. 



5. There is a wide variation in the amounts of tin and gases 

 in the various kinds, and also in the same kind of foods. 



