The Chemical History of a Candle · Platinum, part 2 · Part 7: The extra Lecture on Platinum (optional)
20. Platinum ore, Russian coins, and Deville's plan optional
Goal: Your child can read Faraday's table of platinum ore, explain why Russia's platinum coins failed, and name the three points of Deville's method.
You'll need
- A few coins of different metals
- Science notebook
What's in the book
The make-up of platinum ore from the Urals; Russian platinum coins; Deville's three points (intense heat, the blowpipe, and driving off metals as vapor); platinum melted by the battery; and how lead and platinum combine.
The lesson, step by step
Hook question
SayIf you dug up a nugget of platinum ore, would it be all platinum?
Read together
Read pages 200 to 209, stopping at "His first object is to get rid of the lead."
Look closely at the table of ore on page 200.
Read the table
Faraday's Ural ore: platinum 76.4, iridium 4.3, rhodium 0.3, palladium 1.4, gold 0.4, copper 4.1, iron 11.7, osmide of iridium 0.5, sand 1.4. The printed total is 100.5.
Ask: Which is the biggest part after platinum? (Iron.) Add up the numbers to check the total.
Platinum coins
Russia made coins of platinum. A twelve-rouble coin was worth thirty-six shillings, since a rouble was worth three shillings. But it caused trouble:
but when you have three precious metals (for you may call platinum a precious metal) worked into coin, they will be sure to run counter to one another.
People found it worth while to buy platinum abroad, make coins of it, and bring them into Russia, so the government stopped issuing them. Look at your coins: what are they made of?
Deville's three points
Deville's method depends on intense heat, blowpipe action, and the fact that some metals (like gold and palladium) can be boiled off as vapor, leaving platinum behind.
Watch only: don't try this at home. Faraday melted platinum wire and then a piece of platinum with his huge battery, wearing spectacles:
and it is neither policy nor bravery to subject any organ to unnecessary danger
He also showed that a little lead melts a hole right through platinum foil, and that rolled-up platinum, tin and lead foils flash and explode under the blowpipe. Hot metals and strong electricity are not for home.
Say it back and check
Narration prompts: What is in platinum ore besides platinum? Why did the platinum coins fail? Why did Faraday wear spectacles?
Check questions:
1. What are Deville's three points?
2. What happens when lead is heated on platinum foil?
3. Why is iron a nuisance in the ore?
Safety lesson
Faraday's spectacles remark is worth keeping. Ask: When should a scientist (or a cook, or a woodworker) protect their eyes? Make a short list together.
Afterwards
Notice it this week: safety glasses or goggles wherever you see them: workshops, labs, sports, a dentist's office.
Tip
You can skim the details of the lead process. The two stories, the coins and the spectacles, are the parts children remember.
Answers to the book's problems
1. Intense heat, the action of the blowpipe, and the volatility (boiling off) of certain metals. 2. The lead and platinum combine and melt together at once, making a hole in the foil. 3. It does not boil off as vapor, and while it sticks to the platinum, the platinum will not flow easily. Arithmetic: the ore table adds to 100.5, as printed; 12 roubles × 3 shillings = 36 shillings.
Worked out for this site from the scan. If a number in your copy differs, trust the book.