376 Tin* 
Of tinning Iron* — Of \ plating and gilding Copper . 
Iron is tinned in a different manner from copper. In 
some foreign countries, particularly in France , Bohemia , 
and Sweden , the iron plates, which are to be tinned, are 
put under a heavy hammer which gives, in some works, 
76 strokes in a minute : they can in one week, with one 
hammer, fabricate 4320 plates ; the iron is heated in a 
furnace eight times, and put eight times under the ham- 
mer during the operation, and it loses near an eighth part 
of its weight. Iron and copper are both of them very 
apt to be scaled by being heated, and they thereby lose 
greatly of their weight. Twenty-four hundred weight of 
pure plate copper, will not, when manufactured into tea- 
kettles, pans, See. give above twenty-three hundred 
weight. Twenty-on^ hundred weight of bar iron will 
give a ton, when split into rods, but taking into conside- 
ration all iron and steel wares, from a needle to an anchor, 
it is estimated that thirty hundred of bar iron will, at an 
average, yield a ton of wares.* Thirty hundred weight 
of cast iron is reduced to twenty, when it is to be made 
intor vire ; and twenty-six to twenty -two, when it is to 
be made into bar iron. Steel suffers a much less loss of 
weight in being hammered, than iron does. Cast steel 
does not lose above two parts, and bar steel not above 
four in one hundred, w 7 hen drawn into the shape of ra- 
zors, files, &c. The iron plates in England, are not ham 
mered, but rolled to proper dimensions by being put be- 
tween two cylinders of cast iron cased with steel. This 
method of rolling iron is practised in Norway , when they 
form the plates with which they cover their houses ; but 
whether it was invented by the English, or borrowed 
from some other country, (as many of our inventions in 
* See an instructive pamphlet, intitled, A Reply to Sir L. O’Bri- 
en, by W. Gibbons, 1785. 
