Don't try this at home...
 

I couldn't resist sharing this, extracted from 'Workshop Hints and Helps' from a book by Donald De Carle.

"To clean mercury: Place a 10% solution of nitric acid in an iron ladle and pour in the mercury. Bring the acid to the boil and allow to cool. Dirt and grease will rise to the top leaving the clean mercury in the ladle bowl. Care must be taken not to boil the mercury as the fumes then given off are dangerous..."

The next hint tells you how to re-sharpen files: "Cover the files with water and slowly add sulphuric acid until a solution about 25% acid is obtained. It is essential that the acid is added slowly as considerable heat is generated which expedites the action, but it may also cause a violent eruption if the acid is poured in quickly in bulk."

There are many more like these, involving the likes of caustic soda, ammonia, hydrochloric acid, zinc chloride, oxalic acid, pure white arsenic and potassium cyanide (helpfully described as "very poisonous"). The interesting point is that this book was published in 1965, less than a decade before the Health and Safety at Work etc Act came into force. And not before time! 8-o

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I used to clean my Vespa Scooters' silencer with caustic soda and, when I was a laboratory/technician for a beer company we used a piece of equipment that contained a long column of mercury which, after a number of tests, had to be drained off and cleaned.

The mercury was then poured into a large, glazed sink and, being only 16 at the time as were the other technicians, we use to play "mercury football" with the balls of mercury, (without gloves !!!!!!!)....no wonder "I'm Daft In The Head"

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It puts gas pokers in the lounge and coal gas balloons in the shade!
David

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I have a 1920s "The Practical Mans Book of Things to Make and Do" which gives the Sulphuric Acid file sharpening tip, it also recommends that if find your car has normal glass in the windows you change it for safety glass...

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I have some interesting volumes, published in 1873 if I remember rightly, called "Workshop Receipts". 'Receipts' was obviously used to mean 'Recipes' back then.
Amongst all sorts of useful knowledge is a section on how to make nitroglycerine, with practical advice on keeping the mixture cool, and avoiding breathing the fumes to avoid severe headaches!

Andy

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DeCarle was a clock man, and wrote several excellent texts on practical clock reapir which are still in print.

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Indeed he did, and the book I am talking about is his "Watch and Clock Encyclopedia", a 1965 reprint of the 1959 revised second edition.

Back in those days, anyone with a workshop was clearly expected to be able to buy, handle and dispose of noxious chemicals without the need to consult Product Safety Data Sheets!

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The Arthur Mee set of children's encyclopaedias (Late '50's?) had a chapter on making your own fireworks by buying C, S and KNO3 over the counter from the chemist. I was utterly crestfallen when my Dad told me the latter was no longer freely available. Children of course have the uncanny knack of finding the inappropriate bit amongst a massive number of pages. This was a children's set of books, remember!

Dave

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I still have a gas poker, made it myself and it gets used.

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I love the books from that era. So much dangerous stuff it's unreal. A couple of favourites (sorry I don't have the titles) were proper stinkers. The first involved making your own point contact transistors using a variety of extremely dangerous carciogens and acids. The second was a book on economy valve circuits of which none contained any notable transformers on the mains side of things.

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Yes but..... did those methods (eg file resharpening) actually work? ( I have some dull files :) )

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A nice bit of background about DDeC: https://donalddecarle.co.uk/the-early-years

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Wouldn’t the quoted method be intended to remove softish metals that were embedded in the teeth of the file. It used to be called ‘pinning’ I believe. I can’t believe anything would actually sharpen hardened teeth.

Jim

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I've got one of those home radio repair books from the 1930's that advises you check the polarity of your DC mains by plugging a potato into the light socket and checking which prong turns it green

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I remember a book on model railways which suggests using chloroform as a solvent for chemically welding pieces of perspex together. At least it warns you will have to sign the poisons register.

It was one of many written by Cyril Freezer.

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I clean files with a wire brush and it does help to make them work better especially if they have been used with soft or greasy metal.

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It's amazing, looking back, what you could easily buy over the counter: I remember in the late-60s as a schoolboy going to the local chemist and buying a pint(!) of Carbon Tetrachloride for cleaning switches, and Trichlorethylene (colloquially called Trike) was equally easily available.

There were versions of such solvents deliberately marketed at the man/woman-in-the-street too: little glass screw-lid bottles with a cotton pad in the top called "Dabitoff", and also 'Thawpit'.

You could also buy stuff like 'Killed Spirits' from the chemist - very good as a flux for soldering copper pipe but also great for making holes in your jeans/the carpet if spilled.

My favourite one though was Potassium Hydroxide: I bought a packet of crystals of this when experimenting with 'electrolytic rectifiers'. Mix the crystals with water [it gets very hot!] then try different metals as anode/cathode to see which gives the best diode-action. it depends on the formation of metal oxides on the two electrodes, sort-of like a 'wet' version of the copper-oxide rectifiers. The electrolysis involved can produce some extremely noxious fumes - and don't leave such a beastie running unattended as they are prone to boiling-over (as I found out).


I never did make a really-successful electrolytic rectifier :(

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The consequence of all this stuff being unavailable is that the younger generation have little interest in physics and chemistry and making things, because they can't!

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You can still get all the chemicals. You just need to know where to go shopping.

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I think the intention was to erode the blunted teeth so that some sharp edges would be created - the file will then cut, if not as precisely as when new.