40 



FRUITS AND FEUIT PRODUCTS. 



TABLE 8. Percentage of heavy metals in fruit products Continued. 



Tin was found in all cases except the one sample of apple jelly, and 

 here the consistency of the product was not such as to favor an attack 

 of the metal. Thirteen samples, or more than 50 per cent, contained 

 zinc. While in most cases the amount is small and could not be con- 

 sidered harmful, Nos. 19394 and 20134 have an excessive amount of 

 this harmful metal. Neither lead nor copper was found in any of the 

 samples. The former is not commonly found in appreciable amounts 

 in tinned goods, and the latter is seldom present in more than traces 

 except where it has been added as a coloring agent. 



There is no direct relation between the acidity of the product and 

 the content of tin. Such a relation is not to be expected, since the 

 time of heating for the purpose of sterilizing varies materially with 

 different products, and the quality of tin used is not always the same. 

 Hilgard and Colby showed in their work that the acid-finish tin plate 

 was much more susceptible to attack than the oil-finish plate. 



Sample No. 20168, which contained 1,259 mg per kilogram of tin 

 or 0.126 per cent, was put up in an ordinary tin pail with cover. In 

 this case the poorer grade of tin plate was undoubtedly used, which 

 accounts for the excessive amount dissolved. 



Sample No. 20228, which contained 40.9 mg. of tin per kilogram, 

 was put up in glass and only the tin cover came in contact with the 

 contents of the receptacle. 



