Jump to content

John Cuthber

Resident Experts
  • Posts

  • Joined

  • Last visited

  • Days Won


Everything posted by John Cuthber

  1. Why this should be the question? Because the difference between a show of hands and a secret ballot is not what you vote for , but what others learn about you.
  2. It is important to recognise that they might be right. For the same reason that most people earn less than the average salary. I think the question should be "would you like others to think you are stupid?".
  3. We already thought that number was possible.
  4. I understand that I can write "two up arrow up arrow four is 65536". Which letters didn't you like? More generally. The Berry paradox is a self-referential paradox arising from an expression like "The smallest positive integer not definable in under sixty letters" (a phrase with fifty-seven letters). https://en.wikipedia.org/wiki/Berry_paradox
  5. Probably not because we can get creative about the way we express them. https://en.wikipedia.org/wiki/Knuth's_up-arrow_notation
  6. Buffer solutions and/ or a pH meter. But you will run into a problem. You can set up a calibration and draw a graph of absorbance vs pH. But it will depend on the concentration of the dye as well as on the pH. It is difficult to be sure that you always have the same concentration of dye. Most dyes are a bit unstable and a lot of them are not supplied as pure materials, but as crude products containing salt etc. So, you would have to make a fresh calibration for each set of samples. If you are going to do that- and use a pH meter to do it- you might as well just use the pH meter to determine the pH of your sample. But there's another pitfall in this analysis. pH meter probes always carry some buffer into the solution which you are trying to measure. And that changes the pH of the sample. To measure the pH of very dilute materials (like drinking water or even river water) you need specialist equipment. I suggest that you contact the people who make pH meters and ask for their advice.
  7. What were you expecting? Why would you post that in a thread where someone has actually done the experiment and told you that there is " LITERALLY NO REACTION"?
  8. Not if you apply it to people who are dead. Equally interestingly " Guinness retired the "Highest IQ" category in 1990 after concluding IQ tests were too unreliable to designate a single record holder." From https://en.wikipedia.org/wiki/Marilyn_vos_Savant Fundamentally, IQ is a measure of how well you do in IQ tests and it measures nothing else.
  9. Yes. So? Here's an interesting observation. The IQ test was designed to identify school kids who were struggling with education in order that they could get extra help. But the people you see on the internet asking about IQ are neither schoolkids, nor do they have cognitive / learning issues. They just sound like it.
  10. Yes. And he's quite honest about the fact that they are illusions; not real. And would you accept this as proof of a flying pig? or do you understand that video is quite easy to fake?
  11. "Will science ever stagnate and come to a halt?" Most Friday afternoons
  12. I'm fairly sure that sodium bicarbonate will float in methylene bromide, but calcite will sink.
  13. Yes there is. The reason is science. Sure Did you really think it was magic? Would you like to buy Tower Bridge?
  14. I think they look cute. But I still don't think any of this really counts as a wheel.
  15. The seeds are alive, and they travel on "wheels"
  16. So, aside from the issue of connecting blood supplies / nerves etc, and the fact that wheels are only useful if you have a "road" and the challenge of finding a use for half a wheel? ... tumbleweed...
  17. I'd be surprised if you can't find some metal recycling place that's prepared to take it. Nickel is quite valuable. The Mond process just isn't something that works on a "home brew" scale.
  18. The reaction does happen, but it is very slow. You can increase the rate of reaction with a suitable catalyst e.g. https://en.wikipedia.org/wiki/Urease
  19. Why does the thread title say "carbonate"?
  20. OK. So, without the protective effects of ethanol 30 g of methanol will cause harm. But a litre of ethanol would probably kill you. So, as long as the methanol content is less than about 30 grams per litre or 3% the ethanol will kill you before the methanol does any harm. 30 grams per litre 3000 grams per hectolitre or roughly 2 times higher than the highest figure in the table will be "safe" because of the antidote also being present. OK, so the table can not be anything to do with health- let's face it, the healthy option doesn't include drinking much hooch. The reason is that they don't want people adding industrial meths to the authentic product. You could, realistically get away with adding a bit of meths to something like fruit brandy and blame the methanol of pectin. You can't do that with gin. So it's a practical measure of how much methanol indicates that the product has been adulterated. A quality control issue, rather than a health issue.
  21. What do you think a reasonable "health based" limit would be?
  22. You are missing the fact that the levels are not set on grounds of health. The methanol content is an indicator of what "good practice" achieves. Because there's a lot more pectin in some of the substrates than in others, the methanol levels will be higher. The light fraction is full of acetaldehyde which makes engines knock like hell. Also, there are miscibility issues with methanol and saturated hydrocarbons.
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.