Looking for etched metal specimens (or possibly conc. nitric acid)

I can never remember what the oldest is supposed to be. Is it farming or prostitution? :-)

Chris

Just out of interest, what microscope do you have? I've been looking at a Watson "Standard Metallurgical".

Thanks very much for the reference and the offer. Sorry I missed the reference on Sunday. I read the posts here rather hurriedly.

Best wishes,

Chris

Thanks for all those useful safety tips. If I make any nital I'll follow them, but I might buy some pre-prepared specimens instead.

Just out of interest, what happens (or might happen) if you reuse the pippettes?

Best wishes,

Chris

Thanks. That would explain why they don't list the concentration. For some reason I assumed that "Laboratory Reagent" was pre-diluted stuff for giving to students.

Pity about the £50 minimum order charge. That's more that I want to spend. They don't state their carriage charge either. It's seems they're in Cheshire, so maybe I could pick up a bottle from them? That's if they aren't going to be unnecessarily fussy.

My dad said he bought a bottle of concentrated nitric acid from his village chemist when he was a boy.

Best wishes,

Chris

Depends.

Perhaps there is a bit of alcohol in the pipette, and it reacts with the nitric acid, producing gas, which forces the nitric acid in the bottle to splash up over you.

Perhaps there is a bit of alcohol in the pipette, and the mixture gets hot, maybe melting the pipette or igniting the alcohol when you add the nitric acid.

Worst (maybe) case, you add a bit of alcohol to the nitric acid bottle each time, and the concentration of alcohol in the nitric acid rises until it goes bang, and you die. Or if there is already enough nitric acid in the alcohol, perhaps an ignition as above causes it to explode.

There are other possibilities, including partly-reacted old nital acting as a catalyst to make the reaction in the new nital easier, or metal contaminants form used nital doing the same job.

The list goes on ..

-- Peter Fairbrother

It's fairly pure nitric acid of about 70% concentration, ie with 30% water and only a little bit of other substances. It's the right stuff to make nital with.

Chemicals usually come in 3 main grades, Technical, LR and AR. There are other grades though, eg food, ultra-pure, semiconductor and spectroscopic grades.

Technical grade is approximately "mostly the right stuff", and usually will be about 95% pure, though this will depend on the chemical involved.

LR or "laboratory reagent" is a grade of purity, sort of. Usually LR stuff will be 98-99% pure or so. Really however, LR is saying it is suitable for use as a general laboratory reagent.

AR, or "analytical reagent" is usually even purer, maybe 99.9%. Again it varies, and AR is just saying that it's suitable for analytical work.

These can vary a bit, especially AR, when the label may say that there is only a tiny bit of some otherwise common impurity, which would mess up the use of the chemical in (some) analytical situations; but there may be a fair bit of another impurity which doesn't affect the analytical use of the chemical. AR labels usually give lists of maximum levels of impurities, and an assay.

A few chemicals are slightly different, for instance nitric and hydrochloric acids, ammonia solutions etc. They still come in grades, but it assumed that they contain water, which is not counted as an impurity or a diluent - for nitric acid, it's usually about 70% acid, for hydrochloric acid it's about 35% acid, and so on.

The reasons for these differences vary, for nitric acid it's because it fumes and is dangerous to store at concentrations about 70%, for hydrochloric acid it's because only 35% of HCl will dissolve in water (HCl is a gas), and so on.

However, "nitric acid", unless it has something else tacked on, is usually assumed to be 70% in concentration when you buy the chemical. It also comes in grades as above, technical, LR and AR, but these refer to the levels of impurities in the acid, not the concentration of acid, which will always be 70% or so.

Now that's more than you wanted to know, isn't it :)

You could 'phone and ask.

-- Peter Fairbrother

It's a Metaserv C1850A (read off the plate - I have no idea if that's good or bad!). Here's a picture :

I was planning to strip it down and use the mechanism to make something more suited to my needs, but it seems a shame if someone needs it as-is. I'm sure we could come to some arrangement if you or Steve want it.

I notice there's also some sort of diamond grinder on ebay - maybe this would do for finishing ? Needs a bit of work ..

-adrian

Its a Vickers M12a - I don't remember how much I paid for it, but very happy. However I waited quite a while for a metallurgical one that was at a good price and within driving range - this was in Liverpool.

The top photomicroscopes I used were Zeiss - but you are talking money for one of those.

Best Regards Steve

It's a Metaserv C1850A (read off the plate - I have no idea if that's good or bad!). Here's a picture :

I was planning to strip it down and use the mechanism to make something more suited to my needs, but it seems a shame if someone needs it as-is. I'm sure we could come to some arrangement if you or Steve want it.

I notice there's also some sort of diamond grinder on ebay - maybe this would do for finishing ? Needs a bit of work ..

-adrian

In the end I decided to buy the Watson "Standard Metallurgical" microscope. It should be with me in a week or so. If I get any great pictures, I'll post them for everyone to see!

Best wishes,

Chris

I did. Looks like the cheapest thing for me to do is to collect a single bottle from their premises in Cheshire. They said I can do this with no minimum order charge.

Best wishes,

Chris