XI, A, 4 



Heise and Clemente: Tin Plate 



193 



For rapid, practical tests, where many examinations must be 

 made to determine the quality of a large shipment of tin plate, 

 simple determinations of the amount of coating per unit area 

 will doubtless be found sufficient in addition to tests on uni- 

 formity of coating. Many of the procedures outlined are un- 

 necessarily tedious. 



In most of the foregoing methods the amount of iron alloyed 

 with the tin is not determined, although it appears obvious 

 that it is a factor having an important bearing on the quality 

 of the resulting tin plate. A method which will first remove 

 the coating, including the tin-iron alloys, from tin plate and 

 which will enable the subsequent detenninations of at least the 

 tin and iron in the coating ought to yield more valuable in- 

 formation concerning the quality of tin plate than a determina- 

 tion of the tin only or of the tin and lead in the coating. 



The work here recorded was done for the purpose of studying 

 and developing methods of removing tin from plated iron with- 

 out attack on the iron base, with special references to the 

 analysis of tin plate. 



EXPERIMENTAL PART 

 Different brands of tin plate were used in the work here 

 recorded, but none of these contained lead. A sample of tin 

 plate of uniform appearance and apparently good quality was 

 cut into squares 5 centimeters on a side, cleaned with alcohol 

 and ether, and analyzed according to the method of Aupperle,^^ 

 the final titration for tin being made with iodine solution. 

 The results with different squares were as follows: 



Table I. — Analysis of tin plate by Aupperle method {titration -with iodine 



solution) . 



No. 



Weight 



of 

 sample. > 



Weight 

 of tin. 



Weight per unit 

 area. 



Tin in tin 

 plate. 



Per 



square 

 deci- 

 meter. 



Per 



square 

 foot. 



1 .- __. 



2 



Grams. 

 4.340 

 4.340 

 4.293 

 4.330 

 4.3S4 



Grains. 

 0.064 

 0.072 

 0.068 

 0.071 

 0.064 



Grams. 

 0.256 

 0.288 

 0.272 

 0.284 

 0.256 



Ounces. 

 0.084 

 0.094 

 0.089 

 0.093 

 0.084 



Per cent. 

 1.48 

 1.66 

 1.58 

 1.64 

 1.47 



3„. 



4.. 



6 . 





Average -.. 



4.331 



0.068 



0.271 



0.089 



1.57 





" Size of plate, 5 by 5 centimeters. 



' Loc. cit. 



