TIN SALTS IN CANNED FOODS OF LOW ACID CONTENT. 



looked for the present and can not be regarded as overthrowing the 

 generalization that the products given first in Table 1 contain some 

 substance other than acid that has a marked solvent action on tin. 



Table 2 gives the results obtained in the examination of a series of 

 samples of unknown origin, but whose age is known to be at least as 

 great as that stated. In general the results given therein are similar 

 to those shown in Table 1. - 



TABLE 2. Acidity and tin content of old canned good*. 



STUDY OF CANNED SHRIMPS. 



It is evident from these tables that in a study of the tin salts present 

 in canned foods there is some important factor besides their acidity. 

 It was thought that some light might be thrown upon this subject by 

 the study of canned shrimps. It is recognized by packers that 

 shrimps contain some corrosive substance which greatly interferes 

 with their handling and preservation. It attacks the workmen's 

 hands, causing the skin to peel, and also eats through the leather of 

 their shoes. Tins in which the shrimps are preserved are quickly 

 perforated. Packers have found that this substance seems to disap- 

 pear when the shrimps are preserved with ice. Ordinarily they are 

 caught at some distance from the packing houses and iced in the boats, 

 so that by the time they reach the packer their corrosive property has 

 disappeared to such an extent as to make it practicable to work with 

 them. When caught near the packing house it is now customary to 

 lay them down with ice for a day or so, during which time they lose 

 this corrosive property. 



There were recently received at this laboratory from A. W. Bit- 

 ting several cans of headless shrimps that is, shrimps from which 

 the heads have been removed but not the shells procured by him and 

 packed in his presence at Biloxi, Miss. It was found that they con- 



