MAINE SARDINE INDUSTRY. 85 



On standing, a small amount of a white sediment containing 0.4 to 

 0.9 mg of tin settled out from the solutions when the contents of the 

 cans were transferred to digestion flasks. This was undoubtedly an 

 oxid of tin. 



Of the cans opened directly after processing, those containing dis- 

 tilled water were not attacked. The cans containing ammonia ap- 

 peared to be attacked the most. Next, in order of the apparent 

 degree of corrosion, was the can containing equal parts of ammonia 

 and trimethylamine, followed in order by those containing trimethyl- 

 amine, monomethylamine, and dimethylamine. The apparent ex- 

 tent of corrosion in this series does not conform to the actual amount 

 of tin removed. The can containing monomethylamine lost the most 

 tin, while the least went into solution in the mixture of ammonia 

 and trimethylamine. 



In the lot which stood for three months, the cans containing 

 dimethylamine showed the greatest effect, as well as the removal of 

 the largest amount of tin. The fact that these cans were only partly 

 filled may account for the greater corrosive action. Next in amount 

 of corrosion came the cans containing ammonia and trimethylamine, 

 with monomethylamine third. In this group the apparent extent of 

 corrosion agrees fairly well with the actual amounts of tin deter- 

 mined. 



Of the cans which stood for eight months, those containing ammo- 

 nia and equal parts of ammonia and trimethylamine were attacked 

 the most. Dimethylamine followed in order of severity, while the 

 ones containing trimethylamine appeared to be the least attacked. 

 The amount of tin in solution agreed with the observations made on 

 this lot. Unfortunately no monomethylamine was available for com- 

 parison at this period. 



The variation in the amount of tin found in these solutions at dif- 

 ferent periods may be due to variations in the quality of the tin plate 

 of the cans. No attempt was made to obtain cans composed of the 

 same plate, the cans used being taken from a miscellaneous lot. 



These results, although limited in the number of cans tested, show 

 that weak solutions of ammonia and amines exert a detinning action 

 on the interior of the cans, and that this action increases on standing 

 up to a period of at least three months. 



Conclusions. 



Ammonia and amines are formed in sardines stored for any length 

 of time, the amount depending upon the period and temperature of 

 storage. Sardines held at room temperature contain a higher per- 

 centage of ammonia and amines than when they are held just above 

 freezing. Ammonia and amines in solution are believed to be re- 

 sponsible for a great part at least of the detinning which occurs in 

 sardine cans. 



