These are wonderful. Let me add one of my own to the collection. This is a true story from that same era, maybe a couple of years later when I got kicked out of my third grade class for being a troublemaker and had to go to a special ed class called Mrs. Spencer's Workshop.
199. Make your own printed circuit board
You will need: a common kitchen cutting board, a sheet of copper, a roll of electrical tape, a fish tank, and a supply of nitric acid. And whatever electrical components you need to complete your circuit.
All of these supplies are readily available to a third grader, except for the nitric acid which you will have to ask your teacher to source.
First, design your circuit and test it in your mind. Then tape it out - literally - with the electrical tape on one side of the copper sheet and matching tape on the other side.
Pour the nitric acid into the fish tank.
Dip the copper sheet into the nitric acid. Watch it with your teacher as the acid dissolves the copper, except where you have taped out your circuit.
When all that remains are the taped out traces, remove the copper circuit from the acid and rinse it with water.
Peel off the electrical tape and fasten the copper traces onto the cutting board. This is what makes it a circuit board.
Connect the rest of the components and test your circuit.
Go to the science fair, demonstrate the printed circuit, and explain to the visitors how you made it.
Thanks for your story! I am wondering why your teacher would use nitric acid. Wouldn't iron(III) chloride have been much safer in a workshop with children?
As I recall, it was because I had read up in my chemistry book about what would dissolve copper, and it mentioned nitric acid. So that's what I asked for.
Mrs. Spencer's Workshop was a class where you could pick out your own projects. She would get you the materials you needed, let you do your project, and help you if you got stuck.
You could say that she was my lab assistant here rather than my teacher.
The other safety question for me is why didn't either of us use eye protection!
Diluted enough, the nitric could easily be made weaker than your stomach acid but will still eventually dissolve the copper. Its a sort of linear-ish relationship of concentration vs time so you can trade safety for time (as with most industrial processes, LOL)
I would think dilute iron chloride would not taste good, but you could probably chug enough to get sick.
I believe there would be a similar relationship WRT staining skin and clothes, dilute enough HNO3 would not be TOO much more dangerous than letting kids handle a can of Mt Dew unsupervised, but FeCl in any dilution will stain and damage clothes and skin.
If I had to work with maximal concentration solutions of both, I'd agree and definitely prefer the conc FeCl vs fuming nitric.
This is just priceless. I admire the breezy dismissal of potential harm/injury, and the confident reliance on exercising "reasonable care". Favourite (so far, that is):
26. A flour bomb as a noisy finale to our air experiments
... If you tried to set fire to a small heap of flour you would not succeed. But finely divided flour in a cloud—that can make a completely harmless bomb!
... With a great BANG! off flies the lid of the tin. The finely divided flour has exploded.
It is best to do this experiment out of doors. Not that the explosion is dangerous, but the lid might go through a window or do some damage in the room. It is also important to take care that the lid does not hit you in the face. Given reasonable care this flour bomb explosion is perfectly harmless.
One of the transcriber said:
Another class of projects illustrate the caviler attitude toward environment and health in 1913. These projects involve items such as asbestos, gunpowder, acetylene, hydrogen, lead, mercury, sulfuric acid, nitric acid, cadmium, potassium sulfate, potassium cyanide, potassium ferrocyanide, copper sulfate, and hydrochloric acid. Many references to these have been highlighted in red.
Projects requiring extra skill and care that involve high voltage, melting metals, or other hazards, have the title highlighted.
Wow. Just sublime. Insanely ambitious projects mixed with the insightfully practical and leavened with, er, just so many ways to die. Have downloaded both and will relish reading them thoroughly. Many thanks.
Years back had a teacher who would use this demo to liven up the first class of the year. She would go on at length about how important studying science was, wait til everyone looked half asleep, then bang.
I was reminded of this attitude last week, when I met a TV presenter from my childhood. He was known for doing daring things, the first of which was cleaning the Big Ben clockface. The Daleks were not the only scary thing on 80s BBC TV:
https://www.bbc.co.uk/archive/blue-peter--big-ben-is-cleaned...
I'm surprised by the writer completely ignoring the possibility of blast injury to the lungs...? Blowing into a hose connected to a space in which an explosion takes place would worry me much more than what the lid might do.
My naive assumption is that there’s a combination of two factors going on: 1) the blast force will be proportional to the area through which it’s transmitted, and a narrow hose will have a lot less area than the lid of a can, and 2) if the hose is fairly flexible rubber, there will be significant reduction of the force over the length of the tube.
All of these things are possible, but personally I'd just never risk it by assuming that the pressure wave will escape "somewhere". Call me a coward, but still...
Yes, a small flour puff can make a fancy show and is fairly safe, Mr. Wizard did it on his show decades ago.
Then again, anything, when suspended in air in significant amounts and the right ratios, will explode. Sugar and flour explode just fine. Sawdust, metal particles, and don't drop that cup of flour next to an open flame if you like your eyebrows.
I had an older professor of physics at the university (I was studying physics) - he was a theoretician. Once a year he felt the need to make an experiment "for completeness".
As good as he was as a theoretical physicist, he was a walking disaster with experiments.
In mechanics there is an experiment where you sit on a chair, with weights in your hands, someone makes you spin and then you extend the arms and the movement is slowed down (conservation of momentum if someone is interested).
He wanted to show this, sat on a chair, extended his arms and asked a student to spin him fast. And then retracted his arms next to the torso. He flew two or three meters away from the chair and fell down, with us jumping to help him (he was something like 70 at that time).
After getting back to his senses he continued with an experiment where you hold a bicycle wheel in your hands by the axis, it spins quickly and you cannot flip it right or left. So he did.
And then he was left with a spinning wheel in his hands, wondered a moment what to do with it and simply dropped it on the floor. It is amazing he managed to squarely hit the audio system of the amphitheatre which did BOOM and we did not have sound anymore.
That was the end of the experiments for that year.
You will need: bowl of water, pair of scissors, piece of glass.
It is possible to cut glass with ordinary scissors in any shape you
wish, provided that while cutting you hold the glass and the scissors
as well as your hands completely under water. The water deadens
the vibrations which make the glass crack. Yes, under water, glass
can be cut almost as easily as cardboard.
It's not mentioned, but I'd assume that the glass thickness would be something like a pane from a greenhouse. Might just have to try this one ...
V informative, thanks. Nice to have a better explanation of what's happening (ie the water molecule interaction with glass and the propagation speed of cracks) than the original 1958 document's claim that it was due to water absorbing vibrations.
if you set up any work area for glass, over time, there will be glass dust and shards.. this is brutally dangerous to the eyes, nostrils and other .. cleaning the glass shreds is possible with a strong vacuum, but really a sealed work box works best or extraordinary shop habits. Glass is rewarding when its done, but you know.. you have been warned.
It is called "Toys from trash". From time to time we go there with my younger daughter and we randomly pick an activity. Compared to the book there is little text, explanations being mostly visual. That makes it accessible to non English speaking children.
There were lots of books like this in the 1950s, some of which survived to my own childhood in the 70s. I was thinking for various reasons they probably don't exist now and that's a shame.
But then I realized this is just a Book Of Potential TikTok Videos and felt better about it.
> You will need: group of cigarette smokers, piece of ice, knife.
OK. Curious where this is going.
> Where there is a group of people most of whom have a burning cigarette in their hand or mouth, you can play a smart little trick which shows how unreliable our senses are. Without letting anyone see, make a point on a piece of ice with a knife. Dry it well, then press it firmly against the neck of one of your friends. He will be startled and perhaps angry because you, according to him, have held the burning end of a cigarette against his neck.
Yikes! Legitimately so I would think. On the other hand, while finding a gaggle of smokers is harder than it used to be, the subset of adolescent and post adolescent boys who find it amusing to injure, inflict pain and confuse their friends still seems limitless.
> Then it is your turn to be surprised and show him the piece of ice.
Some good stuff, but also stuff like this, from the Cartesian Diver":
> Air is easily compressible, water is not.
Not significantly compressible, in the sense of reducing volume, but it is pressurisable (think of pressure at the bottom of the ocean), which is what this experiment depends on.
> The water is not compressed by your called ions) and the chlorine atoms (chlorine ions) of which the salt in solution consists.
Wot?
Thinking about my own experiments as a child, my favourite tools were a 12-volt car battery charger, and fire. Sometimes I wonder that I'm still here :-)
I think playing with fire is a basic part of being human. Humans, fire. The fire primate, why we don't have hair or fat for body heat, we have fire and clothes. Like how else are you going to learn but seeing what happens if you eg play with the gauge on a lighter (for education, playing is mostly about learning), more flame, less flame, look at it, marvel at it. Doesn't mean getting burned though for sure there will be burns.
And it's becoming a lost art, like everything's electric, less and less fire in the house for fewer and fewer reasons, fewer smokers smoking less, vaping instead (which I consider good, harm reduction all the way), fewer ways to make fire, offices rarely have incinerators any more, well paper too, fire and paper, another combo. Less metallurgy due to less manufacturing in the States. SF Fire Department actually now do more like...helping the evicteds, because the codes to eliminate fires have worked very well in the regard of preventing fires.
My own worst experience with fire was with a Primus stove (https://en.wikipedia.org/wiki/Primus_stove) when I was about 14. I'd squirted the priming meths alcohol from a squeezy bottle on to the stove and lit it. But then (because alcohol burns with a near-invisible flame I thought it had gone out, so I squirted more on, then ... boom! Squeezy blew open, sending burning meths everywhere.
Luckily alcohol doesn't burn at a high temperature, so only all the skin on my hands peeled off. And this is no criticism of the Primus, just wittlessness on behalf of 14-year-old me.
I don't suppose kids get to do this sort of stuff these days?
I show my kids by doing the same stupid stuff i did as a teen and how "dangerous" it is. Empty bottle of isopropyl alcohol? shake it, hold an electric or regular lighter over the opening - foomf. shake, foomf. shake, foomf. Over and over. The fire doesn't burn the liquid, but the vapor created by shaking the container.
try explaining how a gas engine works to someone that doesn't understand how vapor burns but liquid doesn't.
My latest "prove something" was taking my brightest flashlight and putting it flush against the bottom of a clear container of peanut butter in a dark room. When you shut off the flashlight, the peanut butter fluoresces. It "glows in the dark" for a short time. really cool.
this whole PDF is whimsically old, but it has some good experiments nonetheless.
Which I think is a great game, or was when I played it, I bought when I had no money, it was I think $40, and was very satisfied. I wanted to play it again see what had changed but Microsoft didn't honor my purchase, they wanted me to buy it again. Obviously not in so many words but dude they have hundreds of UI UX people they A/B test everything. They fucking know. They fucking know. It may have been a mistake (there is literally a 0 probability of this), all the same, I went through the whole protocol, did the backup option, the works. Totally agree that piracy is a service problem. Self-service.
If I feel like playing Minecraft again I won't steal it, wrong word--seize it, take my own property back for myself. I own Minecraft in the specific capacity I agreed to--just a perpetual license for myself, no more than one person playing at a time, no piracy, never even looked it up on all those sites only the Russian search engines can parse.
Yeah that's what "must have happened", someone put a ж in there, it didn't compile, Минкрафт. MS database failure, that's the mistake they didn't make. Yeah that makes sense it's a Russian plant getting children to play indoors only, fake TNT fake water fake fire, play video games and become overweight in elementary, obese in sophomore year of High School. US Army complains about this, all these recruits are busted, nearsighted from screens, fat, flat-footed, everyone has a 1-in-1000000 condition that requires favoritism, never gotten burned, never scraped their knees, nothing.
When I was a kid I had some wound somewhere most of the time. Like they even made the clothing with patches in the elbows and knees not because that would be any protection but to get the clothing to last the year.
When I was about 13 years old, a retired engineer (slash wizard) who was friends with my mom gave me a 25,000 volt step-up transformer. Why any adult would do that is beyond me, but I was always very safe with it and managed to do a lot of cool experiments without killing myself. I let my friend borrow it, though, and his brain was calibrated a little bit differently as far as risk behavior, etc. He ended up shocking himself multiple times just because he'd do things like reach over and reposition the leads when the (freaking two inch) plasma arc died out.
Probably a neon sign transformer. The tube won't ionize until tens of thousands of KV but when it does light off, the resistance of the plasma drops to practically nothing compared to the excellent insulator it is when not ignited. Neon tubes are negative resistance devices, 25KV at zero current vs maybe 10 mA at 300 V after it ignites is a resistance of negative 30K or so. The point is a lot of EE work goes into the magnetic design of the transformer such that it current limits to some specified value. If you use a core material and shape that'll saturate at 10 mA but a ratio of number of turns such that it'll output 25 KV as long as the current is roughly zero, that would make a good neon sign transformer.
Much like alcohol there is no minimum safe harmless amount of current thru the heart, but if you have what by neon transformer standards is a very low current transformer, like limited to 5 mA or so, that might be a low enough current to only kill like 0.0001% of the population or whatever. A kid will probably be fine. An old person with heart problems, maybe not so much.
When I was visiting Poland, some friends told me that they had, as kids, a TV show where a man was discussing how to build stuff.
He would start with a set of wires, some wooden tablets, a few screws and a piece of paper. He would draw how "we" would build, say, a house out of this, moved the pieces around and suddenly was getting from below the table some incredibly complex construction they were supposed to easily reproduce :)
I have the original hardback of this book: yellow cover with a black stripe. Happy memories growing up and trying some of the experiments in it including the flour bomb which was shockingly loud.
199. Make your own printed circuit board
You will need: a common kitchen cutting board, a sheet of copper, a roll of electrical tape, a fish tank, and a supply of nitric acid. And whatever electrical components you need to complete your circuit.
All of these supplies are readily available to a third grader, except for the nitric acid which you will have to ask your teacher to source.
First, design your circuit and test it in your mind. Then tape it out - literally - with the electrical tape on one side of the copper sheet and matching tape on the other side.
Pour the nitric acid into the fish tank.
Dip the copper sheet into the nitric acid. Watch it with your teacher as the acid dissolves the copper, except where you have taped out your circuit.
When all that remains are the taped out traces, remove the copper circuit from the acid and rinse it with water.
Peel off the electrical tape and fasten the copper traces onto the cutting board. This is what makes it a circuit board.
Connect the rest of the components and test your circuit.
Go to the science fair, demonstrate the printed circuit, and explain to the visitors how you made it.
Thank you, Mrs. Spencer.