Sulphuric acid

An interestinng use of Hydroflouric acid is the etching of the glass graticules in optical systems.

Again, good old beeswax is used to coat the glass and engraved through to the glass and then placed over the open top of the acid container. By trial and error they leave it for a certain time, then the wax is removed and the resultant etching is filled with black paint so it stands out in the focal plane.

Not many makers use this method now as they have perfected a system of coating Chromium onto the glass which makes the graticules finer and more accurate.

Clive

Hi, when I first started working for my last employer back in 1970 they used HF acid in industrial sand production. I never knew what part it played in the process, as I was just a young-en then, just got told not to go near that bit of kit. Luckily they discontinued it's use shortly after I started there, so never had much to do with it. However I knew then that it could not be put in glass bottles as it would just eat it's way through. They still used it in the lab in small quantities though, and about 25 years ago I asked if I could have a small amount for etching a bit of glass. They let me have some, but only on condition that I sign a well documented disclaimer that the company would not be held responsible for it's use or disposal and I had to accept and sign for some special burn cream. Apparently you can't feel it burning through your skin.

Regards Nick.

Raymond,

'Things I will not work with' is wonderful! This guy can write like P G Wodehouse! My wife heard me gurgling with delight as I read it and asked after the fun. So I told her about my academic interest in explosives (Take note, Special Branch!) and my very interesting books on them, called 'The Big Bang', the 'Terrorist Explosive Sourcebook' and 'Explosives, Propellants and Pyrotechnics'.

Organic chemistry is something I never studied, but I find other people's tales of such experiences fascinating and the reasons why the Battle of Jutland was unsuccesfull is a tale in itself. (Clue: look up Picric Acid)

So Dr Crippen was innocent- he just had aname that sounds guilty.

Nitrogen tri-iodide was one of the favourites when I was in school.

Student teacher makes some, filters it, and nothing happens, throws filter paper in bin as failure.

Later...

Mr Gwynne sets us all up for a 'prac' and goes into the prep room to make his own chemical brew (AKA tea).

Throws tea bag in bin.

We all here almighty bang.

Somewhat shaken Mr Gwynne comes in and , after interviewing us (and we all deny all knowledge of NI3) warns us of the dangers of Nitrogen Tri-Iodide, especially the danger that it only partly decomposes, and many people have lost fingers because they hadn't realised there could still be some left after an explosion.

Mr Gwynne leaves us to get on with our work.

Another, somewhat more modest, bang.

Mr Gwynne returns, this time with brown fingers.

Moral - if you are clever enough to identify a substance through the 'exploding teabag test', you should have the brains not to try fishing the leftovers out of the bin with your bare hands.

Neil

Neil

Did you verify that Mr Gwynne's fingers were brown from the residue of an explosion or was it he lost control as a result the second explosion .

Martin

NI3 was great fun when I was young, Neil. I recall going to Boots the Chemist for some iodine crystals. The pharmacist must have known why, because he asked if I needed any household ammonia to go with it.

But you could buy saltpetre and sulphur at Boots back then, and grind up some charcoal to make gunpowder as per the recipe in "Teach Yourself Chemistry". Much better than NI3 for blowing things up!

However did we survive?

Andy

PS The chemistry teacher's demonstration of the thermite reaction, having gathered us all close to his desk to observe the molten iron running out, is something else which is probably lost to today's youth.

Andy,

You don't mention the chemists' suspicion when you ask for glycerine for icing and potassium permanganate for the fish at the same time

Neil

p.s. just noticed the SCAYT uses an American dictionary - no 'e' on glycerine!

Mentioning Glycerine brought back something that happened when I lived in Milton Keynes, the garden was overun at night with big black and brown slugs.

At that time I had to hand over my Firearms because of the Dunblane fiasco like everybody else who owned pistols.

This left me with some re-loading powder that I disposed of by sprinkling on the lawn and garden borders, next morning I had killed hundreds of these ugly slugs ! I can only think that the Nitro Glycerine in the powder had done them in. As the powder is just cellulose with an addition of Nitro Glycerine and coated with Graphite to inhibit the burning rate.

Unless anyone else has a better idea? It probably gave them a heart attack.

Clive

Edited By Clive Hartland on 27/08/2012 22:16:41

Clive,

AIUI, the propellant is mostly nitro-cellulose (guncotton), though some recipes may nitroglycerine and other additives such as nitroguanidine. (Actually, for the terminally geeky, "nitroglycerine" isn't actually nitroglycerine either, it's glyceryl trinitrate - nitro compounds have a C-NO2 structure, whereas nitrate esters have a C-O-NO2 structure). However, it is probably toxic in the same way; IIRC most organic nitrates are powerful vasodilators.

And yes, I also had to hand in my pistol - only in ~1998, as I only had a .22 Hammerli. Still miss it, though I was never a very good pistol shot, preferred the rifle.

David

Edited By David Littlewood on 27/08/2012 23:31:23

Neil,

SCAYT?

I think glycerin is the German spelling. Everyone knows that people in the USA can't spell for toffee anyway.

Potassium permanganate is readily available on eBay and elsewhere; it is frequently used for staining wood. It used to be used for treatment of athlete's foot, may still be for all I know.

David

We were after impressive bangs, rather than fires, Neil. We didn't get further than weedkiller and icing sugar, and that was getting a bit tricky because (if I remember rightly) it can ignite spontaneously. One of the gang was known as Copperknob, after a bit of shrapnel from the device he made of gunpowder packed into a length of plumbing pipe (known as a pipe bomb nowadays, I think) was surgically removed from his member. Happily, he went on to father several children in later life.

David, I too had to surrender my .22 pistol, an S&W Model 41. Not too big a wrench, though, because I couldn't hit the town I lived in with it, and like you I am more of a rifle shooter. Also, it cost me £80 secondhand, and the £800 I received six years later softened the blow somewhat.

Andy

Andy,

I think it was a WW2 general who said most soldiers he had known couldn't hit the sea from an open boat with a handgun. I recall another said that, in all his long military career, he had only known of 2 people hit by shots from handguns, and they were both on the same side as the shooter.

David

I remember reading once that the gunfights of the old Wild West as shown in films were mostly myth, since the handguns were so inaccurate the duellists had to be virtually nose to nose if they were to hit each other. Wyatt Earp's Buntline special had a very long barrel for that very reason.

I had a .22 hammerli like David and a further collection of guns, a Smith and Wesson K38 Masterpiece and then a Ruger Redhawk.44 Magnum.

Also had a Ruger Mini14 .223 and a Ruger .308 M77.

I reloaded for all the guns except .22rimfire.

All gone now sadly. It was my main hobby apart from the bees then. Maybe why I am so deaf ! I too got a good return on the guns when handed in.

Anyway, nitro powder kills slugs and snails dead !

Clive

Edited By Clive Hartland on 28/08/2012 08:04:28

Iff you read any biographies of the old west outlaws most were nasty killers and all used shotguns.

Oops! The Buntline Special was fictional, I now discover, although there were long-barrelled handguns about at the time. That will teach me to do my research first!

The tales of hand gun inaccuracy are quite reassuring!!

One of the PsITA of my 35 years in the RAF was the annual requirement for range practice. We were issued with S&W or Colts and on one notable occasion myself and 'oppo' were on the range for 10 metre 'double tap'. Once completed the scores were announced .. Me - zilch, 'oppo' - 7 out of 6!!! I always claimed that I would be more lethal throwing the thing!

Rgds

bill

My late Father joined the RAF just prior to WW2 and used to recount his experience of side arm training. A veteran Sergent addressed the assembled office cadets along the following lines:

"Gentlemen, this is a Webley revolver. If you are ever confronted by the enemy I suggest you throw it at them, because it is the only way you are likely to hit them"

It seems to be in line with Cornish Jack's experience!

Chris

There is a lot of controversy about handgun accuracy, I had a Ruger Blackhawk in the 60's that would shoot a 2" group at 25 yards, in fact I shot myself with it. It was a wet afternoon and the sand backstop had grooves cut by bullets and there was water in them and as I fired, the .44magnum bullet richocheted off the water and up to the brick backstop and flew back at me and I saw it coming all the way and it hit me on my left shoulder and just luckily left a bruise 2" in dia.

With the Ruger Redhawk I often fired it at a 100yards and was able to get 3" groups of five shots.

The load was a 240gn bullet and 7grains of Unique powder. When I was in Kenya my friend who was a gunsmith would shoot game to eat and would shoot gazelle in the head at 50yards with a Ruger Blackhawk, the reason being if he hit in the body the hydrostatic shock turned the meat into red jelly.

The Smith and Wesson K38 Special would shoot 2" groups with Wadcutters all the time with reduced loads.

Regarding the service revolvers, they fired the .380 S&W which is a FMJ bullet and is low powered and they would often stick in the barrel. In fact there is a photo of an x-ray showing 5 bullets lodged in the barrel of a service revolver.

Going back to the .44 magnum, I have fired full factory loads (Norma FMJ bullets) the recoil is some 12ft lb and I find it manageable but by preference I down load to a cast lead gas check bullet of 240gn.Much more accurate and manageable.

Clive