Out of curiosity, does this reset/modify the timestamps of the old posts? I was confused at reading comments from "hours ago" I thought for sure I'd read days ago.
Sorry for the confusion—I know it's weird but the alternative turns out to be even more confusing and we've never figured out how to square that circle!
For lower concentrations (< 50%) HF burns aren't always immediately visible (and often not immediately painful), which can delay treatment as people may assume it's not serious.
Other "sources" (using the word loosely as their provenance is unclear)
> "based on the information available, this was a localized issue with only one student directly exposed. Their reported use of dimethyl mercury was unauthorized. MIT does not allow the purchase or synthesis of dimethyl mercury." [1]
Karen Wetterhahn's exposure and death [3] is a cautionary tale of the extreme toxicity of dimethyl mercury, and was instrumental in new safety recommendations, including strongly discouraging the use of dimethyl mercury for any purpose.
Yes, dimethyl mercury is terrifying stuff - it killed Karen Wetterhahn from a few drops that went _through_ the gloves she had on:
> The case proved that the standard precautions at the time, all of which Wetterhahn had carefully followed, were inadequate for "super-toxic" chemicals like dimethylmercury
Sufficiently pure dichloromethane is also fun stuff. It just eats through most any gloves, plastics, whatever. Even PET, and only polyethylene is somewhat resistant.
LD50 about 2mg/kg oral. By oral it's meant that well.. if you soak your hands in it it will be worse.
Still it's the goto thinner for f/ex gluing ABS. I have a couple liters sitting on the shelf right beside me.
You may also be thinking of phosgene, which actually contains no phosphorous at all. But it is extremely toxic see the LC50: https://en.wikipedia.org/wiki/Phosgene
This is not true, and choosing the LD50 of Melathion to represent organophosphates as a whole seems odd. He was probably thinking of nerve agents or perhaps pesticides. Take a look at the LD50's of the former. These are among the nastiest, most lethal substances known to man.
Yes. See for example any number of nerve agents such as VX. https://en.wikipedia.org/wiki/VX_(nerve_agent). Yes, you can quibble over whether they count as "phosphates" given they often have fluoryl or other substituents, but the class is generally referred to as organophosphates, and they certainly have phosphorous in them. Malathion, is also an organophosphate which acts via the same pathway, but only in insects.
There was a time not so long ago when it was common for chemistry teachers to show off pools of mercury in their bare hands.
By the time I first took chemistry classes, though, that practice had stopped, less out of concern of exposure to liquid mercury and more for accidental exposure to gaseous forms due to spills.
When I was in highschool in the 1960s mercury in the chemistry lab was commonplace.
One way to familiarize students with mercury was to have several liters of it in a wide open-top jar and have them force their fist through the mercury pool to the bottom of the jar.
In fact, forcing one's hand through mercury between six to eight inches deep is not easy, some kids found it too difficult to do.
I'd describe my hand as feeling very squeezed and it being forced upwards to the surface with considerable force. The experience was certainly unforgettable.
There were some safety protocols: good ventilation (to minimize Hg vapor) and afterwards hands had to be thoroughly scrubbed with soap and water.
In the UK, purchases made with a credit card are much more protected than a debit card.
If the supplier goes out of business / fails to deliver, the bank/credit card company is equally liable. A Section 75 claim is allowed for purchases between £100 and £30,000.
The Wired article is a little on the sensational side.
The proposal from the energy regulator Ofgem is to require a sufficiently-sized deposit to demonstrate serious intent to build.
It's not an additional fee: if you go ahead and build, it's cost-neutral. It's only an additional fee for speculative proposals, most of which wouldn't go ahead.
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