Q.-->What is the difference between Canadian colonials tokens in brass,
 bronze and copper. How could i see the difference.

A.-->The technical definitions of these metals are:

Copper: an element.  Since nothing is pure, a coin should only be 
required to exceed some certain percentage copper to qualify. 
I don't know a definition, but I will guess 99%.  The primarycontaminant
 in old copper is usually Arsenic.  Copper is the most difficult of 
these to process, as it is difficult to cast and
difficult to cut (easy to strike, though).

Bronze: an alloy of copper and tin, possibly including other
elements as well.  Coins usually range from 1% to 4% tin (more
tin makes it too hard to process--the metal will tend to crack
when it is rolled and the striking pressure gets too high).
Zinc is often added to bronze to make it easier to process.
There is also an alloy known as aluminum bronze that is seen
on some modern coins.  This is an alloy of copper and aluminum.
Aluminum bronze is brassy yellow in color and tarnishes slowly.
Coin bronze is difficult to distinguish from copper, although
it will appear just a bit more orange if both coins are full red
and the lighting is good.

Brass: an alloy of copper and any of a number of elements, but
NO TIN.  The distinction exists here because tin forms a special
crystal structure with copper that makes the metal very hard.
Most brass coins are copper and zinc, with about 4-5% zinc.
These coins cannot be distinguished by color from a bronze coin.
Some coins have much more zinc (up to 25%), such as the Tombac
5 cent pieces that Canada made during the war.  These alloys
have a light yellow color when new.

>From a practical point of view, the distinction is less technical.
Canadian tokens are classified as copper or brass based on color
only.  If the coin looks yellow or "brassy" it is called brass.
If the coin is red (original color) or brown (toned) it is called
copper.  For reasons that I can only guess at, brass Canadian tokens
tend to stay fairly light in color, even after they have toned.
A copper coin cleaned with an acid solution may look like a
brass coin, just to confuse the issue.  If the coin in question
is potentially very valuable, a nondamaging chemical analysis
can be done, I think for somewhere in the $50-100 range.

I suspect that many of the brass Canadian tokens are a copper-lead
alloy.  The motivation would have been that copper-lead alloys
are very easy to cast and roll (that's why your plumbing fixtures
usually have lead in them even though its a health hazard).
Has anybody ever analysed these things?

-- 
S'later, Mike & Karen Marie Locke                  karenml@rahul.net