Does old meths burn less hot?

[Nick Clarke 3Participant @nickclarke3]

Many years ago when you went to the doctors the metal implements were often sterilised in the flame of a spirit lamp and syringes etc (non-disposable in those days) were kept in a rectangular glass dish of spirit with a chromed top.

Father as a GP bought 'mixed spirit' from the chemists for this and my brother and I used to beg some from him for a Mamod engine. I remember asking him if it would be ok for the steam engine because it was not meths and the reply was yes it is a mixture of meths and surgical spirit.

Why it was better for sterilising or a wicked spirit lamp I do not know, but that was what he used.

[Grindstone CowboyParticipant @grindstonecowboy]

Further drifting…. I got some special Loctite "Super Glue for Plastics" a while ago – comes with an activator pen and worked well on the job I got it for. Subsequently came to use it for the next job a few weeks later and the end of the plastic nozzle was blocked with hardened glue, so I cut the end of it off to get some out. The next time (wait for it), I couldn't remove the plastic cap from the plastic nozzle…

Unscrewed the nozzle from the tube to get some out. Came the next time, I couldn't get the nozzle off the tube, so ended up puncturing the tube to get a few more drops out.

I doubt I'll ever be able to use the 50% or so of the contents that were left, and the activator is probably good for a few hundred more jobs.

Rob

[not done it yetParticipant @notdoneityet]

If the OP (and others) wish to improve their aged (evaporated and diluted with the remaining water) mixture they could burn some magnesium and toss the ‘ash’ in the bottle and give it a shake. Alternatively, gypsum plaster (or plaster of Paris) could be heated to convert the hydrated form to anhydrous calcium sulphate and used. Upon filtering the mixture, the ethanol content should be enhanced in the filtrate.

Taking an accurate specific gravity or density measurement would provide the percentage of each component in the mixture. I generally use a hydrometer but I know that refractometers are available – because I have one – with a range up to only 80% alcohol (I think) but could be read a bit ‘off scale’.

Each gram of heated gypsum plaster (after dehydration) will remove about 250mg of water (given sufficient time, I suspect).

Personally, I would distill it if a sufficient volume needed concentrating – but that is illegal in the UK. One would need a reflux still, to achieve consistent results near to the maximum 95% possible. My water still would only achieve about 85% and would drop off in efficiency quite sharply.😀

Edited By not done it yet on 13/03/2021 12:45:15

[Dr. MC BlackParticipant @dr-mcblack73214]

Posted by Mike Woods 1 on 13/03/2021 11:58:54:

Some interesting points points raised in this thread. I have one of those Swedish "Trangia" camping stoves which is designed to run on methylated spirit. The user instructions say to add 10 to15% water to the fuel to avoid sooting. It still boils water very quickly for that outdoor cuppa and other culinary adventures, so thats fine by me. Unfortunately it still soots (more like a hard varnish really) the underside of the pans.

I find that Meths clogs up the jet holes in my Trangia stoves so I use Alcool à Bruler – obtainable in 5 litre bottles in French supermarkets.

It's colourless and I don't have the same problem with clogging.

I have never diluted Trangia Fuel with water.

MC

[HopperParticipant @hopper]

Posted by not done it yet on 13/03/2021 08:29:12:

Automotive brake systems always have a vent to atmosphere. Use silicone brake fluid – more expensive, but non-hygroscopic.

No. There is a rubber diaphragm on the top of the master cylinder reservoir that seals the hydraulic system shut to atmosphere. The vent hole in the master cylinder cap is above the diaphragm, on the outside of the sealed system. No direct contact between atmospheric moisture and the brake fluid.

Just as an aside, you should not use silicone (DOT5) brake fluid in systems designed for DOT 3 and 4 (hygroscopic) unless you flush the system with meths first and then dry it out, in other words disassemble it, because the two brake fluids are not compatible and can form sludge when they mix. And you can't use DOT5 silicone in ABS systems because its viscosity is all wrong. But it is the solution I use on most of my 1970s-90s motorbikes here in the tropics. Dismantle, clean them out and convert to DOT 5 silicone and forget about annual fluid changes of that horrible hygroscopic stuff. Surprisingly Harleys have come standard with DOT 5 silicone since the 1970s, then just recently changed to DOT4. Cheaper I guess. US military uses DOT 5 silicone, so it must be good!

[GeorgineerParticipant @georgineer]

Posted by MC Black on 13/03/2021 00:42:35:

Sorry to disagree but Meths is mostly Ethanol with some (poisonous) Methanol, pyridine for colour and something to make it taste bitter.

MC

Actually pyridine for bitterness and (I think) methyl violet for colour. I understand that they don't use pyridine these days and have replaced it with Bitrex. It certainly doesn't taste as good as it used to!

George B.

[HopperParticipant @hopper]

Posted by Georgineer on 13/03/2021 13:30:21:

Posted by MC Black on 13/03/2021 00:42:35:

Sorry to disagree but Meths is mostly Ethanol with some (poisonous) Methanol, pyridine for colour and something to make it taste bitter.

MC

Actually pyridine for bitterness and (I think) methyl violet for colour. I understand that they don't use pyridine these days and have replaced it with Bitrex. It certainly doesn't taste as good as it used to!

George B.

You need to chill it before drinking. Patience.

Kind of sad that they put the poisonous methanol in there to stop people drinking it but that is the part that slowly kills the addicts who drink it regardless. I guess somebody in HM Revenue did the cost benefit analysis between lives lost and revenue lost and it came up that way.

[BazyleParticipant @bazyle]

This is something that has come up frequently in gauge 1 circles for decades and probably gets a mention in ME postbag back in 190x. I suggest that while the water content of the meths will need energy to evaporate it the effect on steaming will be less than ambient conditions of wind cooling and poor draught or wick length.

[Robert Atkinson 2Participant @robertatkinson2]

The commentors on my methanol commen are correct meths is indeed 95% ethanol plus about 5% methanol. Not sure why I said otherwise.

Surgical spirit is NOT the same it is mostly Methyl Salicylate which is not hydroscopic. In fact there was an old magic of a mixture of surgical spirit and water is shaken and applied to a audience members handkerchief and then set on fire. The water is absorbed into the cotton and protects it while the sprit burns. Not so common now due to lack of handkies and excessive fire precautions.

Robert G8RPI.

[Dr. MC BlackParticipant @dr-mcblack73214]

Posted by Robert Atkinson 2 on 13/03/2021 13:59:55:

The commentors on my methanol commen are correct meths is indeed 95% ethanol plus about 5% methanol. Not sure why I said otherwise.

Surgical spirit is NOT the same it is mostly Methyl Salicylate which is not hydroscopic. In fact there was an old magic of a mixture of surgical spirit and water is shaken and applied to a audience members handkerchief and then set on fire. The water is absorbed into the cotton and protects it while the sprit burns. Not so common now due to lack of handkies and excessive fire precautions.

Robert G8RPI.

British Pharmacopoeia defines Surgical Spirit as 95% methylated spirit, 2.5% castor oil, 2% diethyl phthalate, and 0.5% methyl salicylate.

I believe that the Diethyl Phthalate has a bitter taste; Castor oil is (as many readers will know) commonly used as a laxative!

MC

[michael howarth 1Participant @michaelhowarth1]

The price of meths has rocketed over the last few years and the usual reason trotted out is that it is carriage costs because of health and safety issues etc etc etc. Total baloney in my opinion but anyway, 95% denatured bio ethanol is sold in B&Q for patio heaters and currently retails at about £9+ for 2.5 litres. In my branch of B&Q they "keep it out the back" for whatever reason, so you may have to ask for it. I usually buy my meths from a little independent hardware shop in Horncastle whose proprietor has not inflated the prIce and agrees with my baloney assessment. I totally agree with Bazyle that draughting and wicking are more important in alcohol firing than the odd few percentage points of water but when you get it right, properly designed alcohol fired boilers steam beautifully and are my preference over say gas firing.

Mick

[Grindstone CowboyParticipant @grindstonecowboy]

Posted by Hopper on 13/03/2021 13:18:34:

Posted by not done it yet on 13/03/2021 08:29:12:

Automotive brake systems always have a vent to atmosphere. Use silicone brake fluid – more expensive, but non-hygroscopic.

No. There is a rubber diaphragm on the top of the master cylinder reservoir that seals the hydraulic system shut to atmosphere. The vent hole in the master cylinder cap is above the diaphragm, on the outside of the sealed system. No direct contact between atmospheric moisture and the brake fluid.

Only ever seen that system on motorcycles, mainly necessary because the master cylinder is out in the rain, and also as it's more likely to get spilled when you drop your bike. Not saying no cars have diapraghms, just not seen one.

Rob

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