48 MADRAS FISHERIES BULLETIN VOL. XIII, 



viniting the top and bottom to the body which has also a vertical 

 seam or thick line of solder joining the two lapped ends of the 

 strip which forms the body. The ' half ' tin, as originally obtained 

 for the Government Cannery, was abandoned largely for this 

 reason ; being d" x 4" there are actually 40 inches (more than a 

 yard) of soldered seams in top and bottom, plus the body seam ; 

 this length of seam demands much solder even with the greatest 

 care, much more with inexperienced men or men careless of waste. 



28. The solder used in India is the ordinary stick solder made 

 of lead and tin in varying proportions, but usually one part of tin 

 to one and a half parts of lead, since a soft, easily flowing, readily 

 adherent solder is needed. Though lead is far cheaper than tin it 

 is not always economical to raise the proportion of lead since 

 such solder is less adherent. In America ' drops ' and wire 

 segments of solder are generally used, and since experience has 

 shown the due proportion of solder to a given length of seam, 

 only this much solder is issued ; hence great economy. The most 

 economical use of solder is obtained in 'capped' tins by using 

 'solder-hemmed' caps in which just the requisite amount of 

 solder is run on to the edge of the caps by the can manufacturer; 

 these ' hemmed ' caps are then placed in position and sealed in 

 the usual way. This not only effects economy in solder but saves 

 time and labour and, what is equally important, protects the edge 

 of the cap from rusting. 



29. It is sometimes economical for the canner to make his own 

 solder, but great precautions are necessary to prevent waste by 

 oxidation of the metals, etc., and to ensure a complete and homo- 

 geneous mixture, since the two metals, being of different specific 

 gravities, tend to separate in the melting pot. 



30. Can-making plant. — The plant actually necessary for the 

 small can-making installation is cheap and simple, but in large 

 factories there is usually expensive plant, power driven and largely 

 automatic ; those will not be here described since in India it is 

 usually cheaper to increase output by multiplying small plant 

 worked by hand or small power; any number of cans can be turned 

 out by increasing the number of solderers. 



31. In the Beypore Cannery the following plant — all manual— is 

 used, viz. : — 



(l) A guillotine plate cutter for squaring the sheets and 

 cutting them into the greatest possible number of the strips which 

 form the bodies ; 



