Brazing . 143 
a chemical laboratory in that neighbourhood, in which 
many articles necessary to the arts and manufactures of 
this kingdom are prepared on a very large scale, has 
communicated to us a new fact well worthy of the atten- 
tion of chemists. 
“ Contrary to the common tables of affinities, he finds 
that copper may be precipitated from its solution in the 
sulphuric acid by tin. All that is necessary to the suc- 
cess of the experiment is, that the solution be nearly at 
the boiling point, or actually boiling, when the tin is put 
into it. The tin made use of ought to be in filings or in 
leaf, or reduced to thin fragments by pouring it, when in 
fusion, into cold water. 
“ To the enlightened chemist we need not point out the 
experiments suggested by this new and curious fact, and 
the important results to which it may ultimately lead, 
If copper and tin, by a mere difference in the temperature 
of the solution, may be made mutually to precipitate each 
other, it is not impossible that the order of affinities with 
respect to other metals for the different acids may also be 
inverted by circumstances connected with temperature. 
Should any such results be obtained, they will be produc- 
tive of incalculable advantages in many intricate cases of 
analysis. The different results obtained in apparently 
similar experiments, by equally accurate chemists, may 
perhaps have been owing in some cases to the existence 
©f such a law as we now allude to. 55 
24 Philos . Mag . 284. 
Brazing . The soldering or joining two pieces of iron 
together by melting brass between the pieces to be join- 
ed. Clean well the edges of the iron. Take what cal- 
led spelter solder : or finely granulated brass, or brass 
dust, mix it up with pulverised glass of borax into a con- 
sistence by means of water. Smear with it the place, to 
be brazed, and hold if over the flame of a charcoal fire, 
