Danger, Will Robinson, Danger
I have a small collection of home science books from the 20s and 30s when the notion of "Health and Safety" was still decades away. Many of the experiments are hair-raising. I think my favourite is:

"Amaze your friends by lighting a cigarette on a piece of ice. Simply push a pin-head sized piece of potassium in the end of the cigarette beforehand."
(ubergeekian, Thu 9 Aug 2012, 18:39, 6 replies)

I have -
read a few of these. They are amazing, take this piece of iridium, and watch how it (wish I knew what it would do other than make babies with several heads.

I got bought a chemistry set when I was about 9 and it was rooobish!
(feedingtimeatthezoo day 1 of his bikini diet started, Thu 9 Aug 2012, 20:11, closed)

This sounds like
a Viz top tip from days of yore.
( K2k6 has a proper job these days, Thu 9 Aug 2012, 22:01, closed)

My grandfather had one of these
I think the particular highlight has to be "build your own X-ray tube" (an actual, genuine X-ray producer). What do you do with this highly dangerous device when you've made it? Why, use it to see the bones in your hand, or small pets.
( le brian, Fri 10 Aug 2012, 8:26, closed)

Aha!
We've discovered the cause of the Great Small Pet Cancer epidemic of 1932
( shinyshinyscalp less a man, more a way of life, Fri 10 Aug 2012, 14:58, closed)

I had a Ladybird book of magic tricks
One of them was how to make your fingers give off smoke when you rubbed them together, and as I recall you had to soak the striker off some "safety" matches in water, collect some substance that resulted, let it dry and then add it to your fingers before you wanted to do the trick. To be fair it did note that the resulting substance is highly toxic, but it still told children how to manufacture it at home :/
( emvee cruor deo cruoris, Fri 10 Aug 2012, 8:29, closed)

The Handy Boys book
Has all this and more. Wonderfully, terrifying stuff
(Sir Tainley Barking Ezekiel 23:20, Sat 11 Aug 2012, 21:44, closed)