telling bronze from brass

Is there any reliable way to tell if an article (such as a bell) is made of brass or bronze, without the use of specialised lab facilities? The issue
is important for the many thousands of collectables and antiquities on the market, since bronze is much more expensive.
As I understand it, the brasses and bronzes in common use fall into quite separate groups (high-zinc vs high-tin), apart from a few misnamed alloys. One would think it would be easy to distinguish them, but to do it without lab test equipment and without damaging a collectable item is harder.
Colour: Useless. Certain bronzes have the same colour as brass, and the colour of the patina on ageing is not reliable.
Hardness: Bronzes, espec. high-tin bronzes, are much harder than brass, but it is not easy to estimate hardness informally.
Sound: High-tin bronzes make bells with a much better sound than brass, but it requires a bell expert to be sure, & it doesn't apply to other items.
Chemistry: Is there a test which is simple enough to use as "kitchen chemistry" and sensitive enough to use when one can't cut or file off a sample?
Any other ideas? Thanks
ross -----------
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of
Not without taking a sample and dissolving it in nitric acid, then following the traditional group analysis methods.
--
Terry Harper
http://www.terry.harper.btinternet.co.uk /
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"Spot tests" by F. Feigl (Elsevier, 1954) gives several simple reactions for Zn and Sn. Not "very" destructive, since they demand in general some acid etching on the artifact with a drop of acid, aspiration of the reacted drop with a filter paper tip, and a coloured reaction on the paper.
Some reactions could also be performed on the trace left by the artifact slightly rubbed on a white tile, similarly to some tests used in mineralogy, or by goldsmiths with a touchstone (which is black, for that matter).
There are handbooks dealing with chemical examination of museum holdings (cf. www.google.com--->"museum artifact analysis").
J.J.
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Ross:
Another publication on chemical spot tests is Chapter 4 of the Defense Scrap Yard Handbook (DoD 4160.21H) which can be downloaded unofficially at http://recyclebiz.com/DoD%20Metal%20Testing%20Manual.pdf See page IV-22 and on.
Another possible route is x-ray fluorescence analysis. There are portable units made by companies like Niton and Metorex. Do a google search on the topic "positive materials identification", often acronymed as PMI. You may be able to find a testing lab or inspection company that can look at your artifacts. Whether this makes financial sense or not will depend on how big and valuable your bells are.
Pittsburgh Pete
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