368 On the Manufacture of  Tin-plate. 
sequently requires the tallow to be at a lower 
temperature. On the contrary, if a parcel 
of thin plates were to be worked in a pot of 
tallow which had been prepared for thick 
plates, such a pot would not be hot enough 
to effect the intended purpose. 
It is a common observation that in most of - 
our manufactures, and in all chemical specu- 
lations, theory and practice are generally at 
variance—but there are few manufactures 
perhaps, where there are so many minutiz 
which would escape the notice of a casual 
observer, and yet that require to be carefully 
attended to, in order to produce a good result, 
as in that which we have now been describ- 
ing—and should the perusal of this paper oc- 
casion but one individual to pause, who was 
about to enter into a new concern with which 
he was only partially acquainted, I shall have 
written to a good purpose. 
« But to return to the process. When the 
plates are sufficiently brushed, they are again 
immersed one by one in the pot of melted 
tin, as has already been remarked, and im- 
mediately from this they are put into the pot 
of tallow above mentioned. This pot has 
pins fixed within it, in such a manner as to 
prevent the plates from touching each other ; 
and this part of the process is conducted in 
the following manner. 
