Originally posted by not_important
Run of the mill nails are generally made with mild steel, which is at the higher carbon content end of the low carbon steels - 0,15 to 0,3 percent
carbon. It may also contain up to a percent or so of manganese, a half percent of so of silicon, and possibly a fraction of a percent of copper.
Other metals will be in rather small fractional percentages if at all.
Bright does mean just the bare steel, no intentional coating applied. Don't be surprised to find a trace of oil on them, though.
The Sn/Cu/(Se,Te) solders generally have between 3 to 6 percent copper, centered in the 4 to 5 percent range. Selenium or tellurium is in the range
of 0,1 to 0,3 percent, below that it doesn't enhance the melting and above that the solder tends to get 'runny'. That amount of Se/Te doesn't seem
likely to give more than a film, not a distinct layer. If you're using tech grade ('hardware store') HCl I'd be inclined to blame yellow colouration
on iron in the acid.
It is possible that the solder is crystals of one metal in a matrix of another, with most of the alloying metals ending up in one phase or the other.
Treatment with acid could preferentially dissolve one phase leaving the other as a powder, which would appear grey from its fine subdivision. Wash it
free from acid, rinse with alcohol and then acetone, dry, then press between hard non-metallic surfaces (even two rounded rocks) and see if you can't
form a metallic film.
Agricultural or even horticultural grade phosphates are likely to be a mess. Some calcium, some sulphate, traces of fluoride, iron, aluminium, and
silicon; depending on how honest the manufacture trace amount of other heavy metals show up as well. If you don't make it into a paste with a little
water before adding acid, expect bubbles from trapped air and from the reaction between surface and complexed water and the concentrated H2SO4.
There's at least a half dozen simple compounds that smell "like ozone", most people's noses are not very good at telling the difference. If you don't
actually run tests to distinguish between them don't assume ozone.
The actual volume of something suspended in a liquid can often be deceptive. Isolating and weighting is the way to go to see if what you have is a
significant component or just a trace product. Even filtering and washing can help, although some precipitates can be rather bulky and hold a lot of
water.
[Edited on 27-4-2008 by not_important] |