Quantities of Tin and Hiidrogen in "Springerfi." 163 



fruits and vegetables. He found that shrimps contain a cor- 

 rosive substance which attacks tin vigorously. The compound 

 N (CH.i) Hii isolated from this product dissolved tin slow^ly. He 

 investigated the action of several alkaline substances, amino 

 acids and purine bases, and found that many of these sub- 

 stances would dissolve tin in considerable quantities. His con- 

 clusion was that the action of nonacid foods was due to amines 

 and amino acids. 



W. Rossee and Von Morgenstern, in an article entitled "Ab- 

 normal Amounts of Tin in Canned Foods, ""^ state that canned 

 foods always contain some tin removed from the receptacle, 

 but usually only small amounts. Large amounts are dissolved 

 when the can is left open for some time. Canned spinach, 

 originally containing 18 mgs. of tin, after six days' exposure 

 contained 1,038 mgs. per kilo. Similar results were obtained 

 with other vegetables. They state that the tin forms insoluble 

 compounds with the vegetable substancv3, and is not redissolved 

 by the gastric juice. Their conclusion is that the small amounts 

 of tin usually found in canned foods are not to be considered 

 injurious. 



H. A. Baker, in his article, "The Disappearance of Oxygen 

 in Canned Food Containers,"^ states that the gases in the head 

 space of "springers" are never more than three — carbon di- 

 oxide, nitrogen and hydrogen. He defines the term "springer" 

 as "a trade name given to cans with bulging ends, which con- 

 tain perfectly sound and sterile food products." The source of 

 these gases he states as follows : 



Carbon dioxide is produced during the time of processing, 

 and may be produced in excessive amounts if the time from 

 the beginning of the preparation of the material to the period 

 of sterilization is not short. 



Nitrogen is present as a residue from unremoved air. 



Hydrogen is present as a result of the action of fruit and 

 vegetables acids on metallic containers. 



The disappearance of the oxygen originally present as a 

 constituent of the air left in the head space of the container he 

 attributes to at least three causes, as follows : 



(a) It may combine with the metals tin and iron, forming 

 oxides. 



5. Z. oflfentl. Chem. 20, 171-172, 1914. 



6. Original Communication, Cpngress of Applied Chemistry, vol. 18, 1912. 



