A new system of chemical philosophy, Volume 2, Part 1Dalton, John
Science
A new system of chemical philosophy, Volume 2, Part 1
Dalton, John
Atomic theory; Chemistry, Inorganic
1. _Lead and zinc._ These two metals seem to have a weak affinity. They
are easily united, or rather mixed, in any proportion by fusion under a
little tallow. But however they may be mixed there is a strong tendency
to separate again, which no doubt is occasioned in part by their great
difference in specific gravity.
I have fused lead and zinc together in various proportions, from 6
parts lead to 1 of zinc, to 1 part lead to 2 of zinc. The compound
usually gives a specific gravity rather greater than the mean; but upon
being broken the fracture is often like that of zinc in one part and
not so in another; and the analysis of fragments proves that a great
difference exists in their composition. Subsequent fusion sometimes
improves the combination and at other times the contrary. Six parts
lead and 1 of tin gave a compound as nearly uniform as any. It was
11 specific gravity, harder and whiter than lead and had much the
appearance of pewter, that is, the alloy of tin and lead.
2. _Lead and bismuth._ These metals alloy well. Three parts lead and 2
of bismuth unite by fusion and form a tenacious alloy which fuses about
340°. Muschenbroek found it ten times stronger than lead. It grows dark
coloured soon by keeping. Its specific gravity by my observation is
10.85, which is rather greater than the mean. It is constituted of 1
atom of each metal, or 62 bismuth to 90 lead.
Three parts lead and 4 bismuth (1 atom lead to 2 bismuth) fuses at
250°. This is the lowest temperature at which any alloy of two metals
fuses. With a little tin it makes the triple alloy which fuses lower
than any other metallic compound, without mercury, as will be shown in
the sequel. The specific gravity of this alloy of lead and bismuth is
10.7, which is greater than the mean.
The alloy of 1 part lead and 2 bismuth (1 atom of lead and 3 bismuth),
fuses at 280°, and is of 10.1 specific gravity, or rather less than the
mean.
The alloy of three parts lead and 1 bismuth (2 atoms of lead and 1 of
bismuth) fuses at 450°. The specific gravity is 11, or rather greater
than the mean.
3. _Lead and antimony._ These two metals combine by fusion in any
proportion. The alloy is of a fine grain and is brittle or flexible
as the antimony or lead prevails. The principal use of this alloy,
I believe, is in the formation of printers’ types. The small types
require a harder alloy or one with more antimony; the large types
have a greater share of lead as being less expensive. On examination
of the different types I find 3 proportions of the alloy principally
in use. The smallest types are cast from a mixture which very nearly
corresponds with 40 parts of antimony to 90 of lead (or 1 atom to 1).
It is hard, has a fracture like steel and is of the specific gravity
9.4 or 9.5 nearly, and fuses about 480 or 500°. The proportions were
determined both by analysis and by inference from the specific gravity
of the metal.
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