MAINE SARDINE INDUSTRY. 83 



years to be covered with a white coating composed of stannic oxid, 

 phosphoric acid, and iron. He attributed the corrosion to the action 

 of phosphate and ammonia contained in the codfish and lobster. 



Determinations of the total amount of tin in packs of sardines in 

 mustard sauce and of the tin content of mustard sauce, plain and 

 fortified with acetic acid, when packed separately, showed that more 

 tin was present in the fish and the sauce than in the sauce alone. 1 

 This observation is in agreement with the conclusions drawn by 

 Goss(lO) who stated that the tin which is dissolved from the can 

 forms an insoluble compound (by adsorption) with the protein and 

 carbohydrate (starch) elements of food. The active materials, acids 

 or alkaline substances, responsible for the solution of the tin are then 

 left free to dissolve more tin. This action may go on until no more 

 tin can be taken out of solution by the food products within the can, 

 or until detinning is complete. 



It having been shown that diamine and monoamine are asso- 

 ciated with ammonia and triamine, as constituents of the total vola- 

 tile alkaline material formed in sardines (p. 75), solutions of all 

 these amines were used to determine the extent of corrosion when 

 present in sardine cans. The amine solutions, in approximately 

 twentieth normal strength, prepared from Kahlbaum's highest 

 purity 33 per cent solutions, were introduced into the ordinary quarter 

 oil cans. The interior of the cans and the lids were thoroughly 

 cleaned by washing with alcohol and ether. The lids were then 

 soldered on and the solutions introduced by means of a pipette 

 through a tap and a vent hole in the end of the cans. As soon as the 

 cans were filled, these holes were closed by a drop of solder. The 

 cans were next processed for one hour in boiling water. One set was 

 opened immediately after cooling and the others placed aside for 

 future examination. The results of the determination of tin in the 

 solutions after being removed from the cans, and the extent to which 

 the inner surfaces of the cans were corroded are given in Table 36. 



1 Unpublished results on file in the Bureau of Chemistry. 



