Metallurgy and The Conversion to "Base" Metal Shillings, 1920

[VickySilver]

I recently tested a pattern 1920 shilling, and the metal content came to:

Silver - 51.67%

Copper - 39.57%

Nickel - 7.36%

Manganese 0.28%

Arsenic (!) 0.015%

The George V standard was in 1920 evidently"

Silver - 50%

Copper - 45%

Manganese 5%

By 1924, this was at:

Silver - 50%

Copper - 50%

Any comments or interest???

[Rob]

Was that run against a standard?

Davies noted that any scrap from the war machine was fed into the mix initially, hence the highly irregular compositions. I might have expected a contribution from brass.

[Peckris]

I do know they had great problems with the new alloy, especially from 1920-22. And that there was experimentation with nickel just after that. The 50% silver 50% copper comes as a slight surprise - I thought they had one or two other things in there in small quantities, e.g. tin?

[VickySilver]

I must admit to not having the equipment, and that it was also a surface spectroscopy (XRF), thankfully non-destructive. I have a couple others (denominations) that I will try the next time I get a chance. I seem to recall the BM having a couple of different specimens of differing metal alloys of same period.

I will also see if I can manage either the 1923 or 4 "nickel" pieces, the latter date evidently struck to 5.0 and 5.7 gm. standards but the alloy of which I have not seen published.

[Rob]

I can't help with the nickel analysis as I forgot to do mine when I did all the Weyl patterns.

[VickySilver]

The local University charges outrageous sums for any investigations, so have left them alone. Alas, my alma mater is too far away to use them as I have a few specimens I would like checked.

[Rob]

Find a microscopist with an interest in coins

I have got my customers interested in something because it was old and after a short time they have offered to do it when they had a spare 5 mins.

[Mr T]

Just curious, where's the best place to read about the history of these patterns?

[Coppers]

I recently tested a pattern 1920 shilling, and the metal content came to:

Silver - 51.67%

Copper - 39.57%

Nickel - 7.36%

Manganese 0.28%

Arsenic (!) 0.015%

The George V standard was in 1920 evidently"

Silver - 50%

Copper - 45%

Manganese 5%

By 1924, this was at:

Silver - 50%

Copper - 50%

Any comments or interest???

Arsenic in the coins we collect?

http://books.google.com/books?id=o-5AAQAAMAAJ&pg=PA290&lpg=PA290&dq=copper+coins+arsenic&source=bl&ots=Q3qbFU4TmX&sig=DcVJX6j3jArFiNiCobCuXdWTBso&hl=en&sa=X&ei=AIjcU_DGIoGVyASu7oGoAQ&ved=0CDcQ6AEwAw#v=onepage&q=copper%20coins%20arsenic&f=false

[DaveG38]

I recently tested a pattern 1920 shilling, and the metal content came to:

Silver - 51.67%

Copper - 39.57%

Nickel - 7.36%

Manganese 0.28%

Arsenic (!) 0.015%

The George V standard was in 1920 evidently"

Silver - 50%

Copper - 45%

Manganese 5%

By 1924, this was at:

Silver - 50%

Copper - 50%

Any comments or interest???

Arsenic in the coins we collect?

http://books.google.com/books?id=o-5AAQAAMAAJ&pg=PA290&lpg=PA290&dq=copper+coins+arsenic&source=bl&ots=Q3qbFU4TmX&sig=DcVJX6j3jArFiNiCobCuXdWTBso&hl=en&sa=X&ei=AIjcU_DGIoGVyASu7oGoAQ&ved=0CDcQ6AEwAw#v=onepage&q=copper%20coins%20arsenic&f=false

Not a major problem as the elemental metal isn't poisonous - its the oxide which is deadly. Plus, of course, the concentrations are very low, so nothing to worry about.

[VickySilver]

I guess technically that at least this pattern is not base metal - %52 silver!!! I may drop off a couple of patterns for analysis come November if I can not sooner.

[ozjohn]

What was this pattern 1920 shilling?

[Mr T]

Just curious, where's the best place to read about the history of these patterns?

For anyone wondering, Peter Davies in British Silver Coins covers a bit of the history, though not a lot.

[Rob]

I recently tested a pattern 1920 shilling, and the metal content came to:

Silver - 51.67%

Copper - 39.57%

Nickel - 7.36%

Manganese 0.28%

Arsenic (!) 0.015%

The George V standard was in 1920 evidently"

Silver - 50%

Copper - 45%

Manganese 5%

By 1924, this was at:

Silver - 50%

Copper - 50%

Any comments or interest???

Arsenic in the coins we collect?

http://books.google.com/books?id=o-5AAQAAMAAJ&pg=PA290&lpg=PA290&dq=copper+coins+arsenic&source=bl&ots=Q3qbFU4TmX&sig=DcVJX6j3jArFiNiCobCuXdWTBso&hl=en&sa=X&ei=AIjcU_DGIoGVyASu7oGoAQ&ved=0CDcQ6AEwAw#v=onepage&q=copper%20coins%20arsenic&f=false

Not a major problem as the elemental metal isn't poisonous - its the oxide which is deadly. Plus, of course, the concentrations are very low, so nothing to worry about.

Arsenic has been used for centuries to impart a 'mint freshness' look to debased coins. If you compare say the modern Cu-Ni proofs and a silver proof of the same type, it is striking that the silver proof is 'whiter'. This is the look that the addition of arsenic tries to emulate.