TIL that the four boxes sometimes seen on old gas cylinders are supply companies trying to cover swastikas stamped by the Nazi's

annoclancularius · 8 days

It occurs to me that the companies might just have kept going with the box stamp on new cylinders for the sake of not having to re-tool their equipment, and so that customers don't think something has changes with the product...

No evidence for this, purely conjecture...

klinonx · 16 days

yes - by about 10 elements!

g-rad-b-often · 16 days

If you haven't seen it before, check out Dylan Styles' tenderbutton blog entry 'Hexanoic acid smells like goats'. The blog is now archived, but you can get it here http://archive.tenderbutton.com/?p=108 (login=tender pw=button)

annoclancularius · 17 days

<plug> www.chemistryworld.org </plug>

Onlythefinestwilldo · 17 days

That might work with a solid stopper, but he's got a funnel gasket in there....

mz27 · 25 days

for some reason I seem to remember it only works if you have a separate numberpad - or if you turn on the laptop numberpad.

Who knows why?

merlo_ · 25 days

Click for the benzene ring but don't have it joined to the rest of the molecule in the first instance. then select the ring and rotate it by 60degrees (this is a function in the object menu). Then select the carbon on the ring you want to join to the rest of the molecule, and the carbon where you want it joined (by holding down shift and clicking the two) and select 'join' from the object menu.

alternatively, just draw a cyclohexane ring in the first instance and fill in the double bonds yourself - only takes 3 more clicks and 1 second...

woodsja2 · 28 days

Fair point - that explains a lot, including the insane hourly chargeout rate, and why the cost of washing up is so much higher than new glassware.

Khea · 28 days

Seconded, but I agree safety fist is the better option. If there's decomposed grignard you might also have pressure of ethane gas...

woodsja2 · 28 days

surely just hire a cheap school leaver and buy a lab dishwasher. Some of the glassware you're disposing of is probably worth reusing.

Does the glassware just get destroyed? Or is it donated to local schools? Those guys would be massively grateful of some extra glassware - there are groups scrimping and saving for RBFs and wep funnels!

woodsja2 · 28 days

Someone should introduce you guys to the wonders of the 3-separating-funnel technique.

Set up a stand with 3 rings/clamps and 3 sep funnels the same size (all taps closed!)

Add your quenched aqueous rxn mix and the extraction solvent to the first flask. Add more extraction solvent to the second and third flasks.

Once you've shaken and settled the first extraction, drain the aqueous into the second flask, repeat and drain into the 3rd flask. Repeat and drain off the aqueous into a beaker/conical flask.

You now have your organic extractions in 3 flasks and can tlc to check extraction efficiency. Combine the organics and you can then do washes with brine/ammonium chloride etc as required.

It's fast, efficient and allows you to follow the work-up more effectively. The only downside is it creates a bit more washing up...

Edit: typos

weltschmertz · 1 month

If you're in the UK, the best place to look is independent schools - they often don't require formal teaching qualifications and will put you through an on-the-job PGCE equivalent.

Also, while the salaries don't really compare to Chem industry, they are far from pittance. There are regular, defined increments and the pension provision is amazing - most schemes will pay around 15% employer contributions! Plus if you get to a head of year or head of department kind of role, the salaries are in the region of £40-50k plus

weltschmertz · 1 month

Have you ever tried high school teaching? My advice would be to try and get some experience somewhere first - I don't know whether this will work in the US system, but you could see if you can go part time in your job to get a taster of what teaching's really like. You may find the reality quite different from your imaginings (this works both ways - it could be even better and cement your decision or you could be put off for life!). That said, if you're really unhappy where you are, and have a strong desire to teach, that's the best reason to go into teaching. Only passionate teachers can inspire students, and your real-world chemistry experience will add perspective to your teaching as well.

Khea · 1 month

the trade-off between methanol and water is that methanol is flammable - if things start going a bit fast, then you get MeOH evaporating and a potential fire. for the large volumes it sounds like this guy has, I think ice/water or Chemjobber's suggestion of dry ice is probably best

Khea · 1 month

One more thing - to be extra safe, use iced water - it'll slow things down a lot and control any exotherms

omnicat · 2 months

Coppiced Hazel is traditional in the UK. It's not as fast growing as bamboo, but the staves are much more attractive and very sturdy http://www.allotmentforestry.com/fact/growown3.htm

christycreme · 2 months

Hi christycreme

I've grown squash with corn before, and weaving the vine in and around the corn stalks as ground cover works quite well. If you're in containers, you should be able to hang the squash fruits over the side to stop them sitting on wet soil.

I'm dubious about adding beans into the mix - i know the idea is that the corn provides support and the nitrogen fixed by the bean root nodules help both, but I think you'll just end out shading the corn out and stopping it from fertilising properly. That's another thing - if you're putting corn under a porch, make sure it's not too sheltered as it's wind fertilised - that's why you need to plant in blocks (containers should work fine) not rows.

A magazine I read called Grow It! there was a column about this system, and the guy found that, yes, they will all grow, but none will do as well as they would separately - you might be as well planting up separate containers of corn and beans with a couple of squash vines trailing out of each onto the floor.

WannaFly37 · 2 months

I'd take a lot of the stuff the marketing department of Monsanto says with a healthy pinch of salt. But they do have to do a heap of research and present the data to the regulators before a product gets passed. Plus, there's a lot of independent scientists with exactly the same idea checking up on their claims.

Here's a report from the Canadian Government that has a lot of primary literature references. http://www.cdpr.ca.gov/docs/emon/pubs/fatememo/glyphos.pdf

After a read through that, it looks like it takes a few days to a couple of months for the glyphosate to break down/clear from the soil. However, once it's in the soil it binds seriously strongly to the soil particles, which means the plants won't take it up from the soil - only when it's on their leaves.

In the soil, it's broken down by soil bacteria - so the healthier your soil, the faster it'll break down

WannaFly37 · 2 months

Cool - sorry if that sounded like a rant, btw. I'm a chemistry PhD and find it really irritating when people have a generic fear/hatred of 'chemicals'. Growing without using unnecessary amounts of chemicals (whether they're 'natural'/'organic' or synthetic) is definitely the way forward, and whatever you do on your plot, it is almost certainly better than commercially produced crops which will have been sprayed at regular intervals whether they needed it or not.

My point, I suppose, is why deprive yourself of the perfect tool for the job you're doing. You could spend hours pulling up all the weeds by hand and tilling them up, but if it is grass it will grow back from root fragments. Roundup kills the roots too, and as long as you don't go crazy with the concentration and don't compost the dead stuff, there's no chance of anything getting into your crops.

This is certainly not the case for other weedkillers and pesticides, and I can understand wanting to avoid those as much as possible. However, some of the alternatives touted as 'organic' are just as bad.

If you want to be really organic, then the best thing to do is probably clear the bed manually/with your tiller. Then plant a fast growing green manure crop like a caliente mustard. When you chop down the mustard and dig it in, it releases a defensive chemical called isothiocyanate that kills other weed plants and boosts friendly bacteria in the soil. The downside of this is that you won't be able to grow any crop this year, but on the upside your weed burden will be much lower in subsequent years.

You could compromise by clearing manually, making do with the weeds this year, then planting the green manure in the Fall for overwinter - keeps weeds down, stops rain washing nutrients out of your soil and gives you a green manure/biofumigant boost in the spring.

WannaFly37 · 2 months

Just out of interest, what's your motivation for not using roundup? It would be by far the best way to get your plot up and running as you'll end up regrowing any perennial weeds otherwise

Glyphosate (the active ingredient) breaks down in contact with soil, so isn't going to be a problem contaminating your crops.

Would you happily use Bordeaux mix as a fungicide (which is classified as organic)? It contains copper sulfate, which is significantly more toxic to worms and soil-based microbes that are beneficial if not vital to your growing success. Do you apply fertiliser (other than manure) to your plot?

There is a lot of misrepresentation about 'organic' growing. As long as you use chemicals sensibly and minimally, there is no reason why the food you grow should be any less 'safe' or more 'contaminated' than anything you could buy elsewhere. most food that you buy labelled as 'organic' has been treated with chemicals just like the 'non-organic' stuff. The difference is that those chemicals have very little regulatory scrutiny to make sure they're actually safe - most are justified on historical grounds and the fact that they're 'natural', which has absolutely no bearing on their safety - lots of natural things are very toxic indeed!

The key thing is not to apply chemical pesticides/weedkillers unless you absolutely have to. In this case, roundup is by far the best option if you really want to be growing this year, as it will kill the roots of the weeds as well as the tops (as long as you leave it long enough to work - 2-3 weeks should be about right)

IHTFPhD · 2 months

Basically the problem was solubility/dissolution kinetics rather than absolute activity, but the release rate has a massive effect on dosing as you can imagine. Plus the fact that once it had crystallised in the new form it kept going and took a long time to work out how to get the original form back.

Oh, and the second polymorph wasn't covered by the patents as it was unknown on filing, despite efforts of the process boys to find any.

I bet some process/manufacturing chemists had a pretty crappy day that day

ScienceParty · 2 months

MS/PhD would be a cheaper hire than a postdoc (as I'm sure ChemJobber appreciates, expert that he is!). I never understood why recruiters say people are 'overqualified' but basically it comes down to cash, plus the fact that they think if they don't pay a salary that the same person could get elsewhere they won't stay around.

Personally I think that's trash - if an 'overqualified' person wants the job and is willing to do it for the salary offered, that surely better value for the company as they'll probably do a better job! That said, it does depend on the individual involved

dashed · 2 months

From personal experience, be really careful putting the LN2 into the bottle - use a funnel or something and hold it just out of the top so there's space for evaporating N2 to get out, otherwise the bubbles of N2 coming out will disrupt your pouring of more liquid in (the cold bath will help here). You also need to work quickly to make sure the neck of the bottle doesn't freeze so you can still get a good seal with the lid.

Then, once you've got the whole thing set up and dropped in the bin, don't ever, ever go back to it - just like a lit firework.

A friend of mine nearly had her hand blown off and was deafened for a couple of hours doing this. That's not to say it can't be done safely, but thought it was worth sharing my experience.

Edit: Dry ice will probably do the same thing, but slower (put a little water in the bottle to speed it up). However, it's a whole lot easier and safer to set up

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