> A hundred years ago is well into the period of silver-on-glass. If you
can't
> find any speculum metal you can always get to blow yourselves up with silver
> fulminate...
I made my first mirror when I was twelve, using Texereau's 1st edition and ATM. Either my library did not carry Sky and Telescope, or I didn't look in the right place, as I did not find it until I moved to California. So, though ATM mentioned vacuum aluminization, as far as I knew I would have to build a vacuum tank myself if I were to use it.
So I chemically silvered my first mirror. I purchased the chemicals at the University of Idaho chem stockroom (my dad came along to vouch for me). (U of I is in Moscow, Idaho). They were OK on selling me everything - even fuming nitric acid! - except for the pure ethanol. You need non-denatured pure alcohol for this. Considering that one dilutes the alcohol anyway, I think you could actually use some quality vodka, but I wanted to follow the recipe. The stockroom clerk made us promise not to tell anyone we got it there (which I'm breaking, but it was a long time ago).
It was very difficult to do. One surprising thing (though obvious in retrospect) is that every surface in the container gets coated, the back of the mirror, the baking dish we used, everything. I must have stripped and resilvered the mirror twenty times before I had a coat I could live with, and even then I did not consider it a very good job.
Two big problems I had were getting the mirror clean enough (even with fuming nitric acid) and getting a uniform even coat.
Later on I consulted my father's chemistry books and ATM to see how actual silver fulminate is made. It does not form if you are careful about handling the chemicals - I think it arises from leaving the old silvering solution lying around. If you are _trying_ to make it, though, it is quite easy. I made a small test tube full, and left it under water in the test tube, which I corked and packed in wadded paper in my wastebasket in my bedroom. A few days later I went to retrieve it so I could take it outside and detonate it, and found shards of glass and brown residue blown all over my wastebasket! Good thing mom wasn' t home when it blew. The top of the test tube was intact, with the cork still in, but the bottom was blown to tiny bits.
Word to the wise: don't let your twelve year old kids play with fuming nitric acid. I also tried to make guncotton, but couldn't get it to detonate, just burn vigorously.
Cheers,
Mike Crawford Mike_Crawford@QuickMail.Apple.Com