1. Ψ*Ψ on January 9, 2007 11:33 PM writes...

Exhaust from a fume hood where a thiol reaction was being carried out once evacuated several buildings downwind.

2. Thomas McEntee on January 10, 2007 7:53 AM writes...

Back in the late 1960s in one of the U. Colorado Chemistry Dept graduate labs, I watched as a friend accidentally knocked an unopened bottle of t-butyl mercaptan--it may have been a 50 g bottle but then again, it might have been 250 g--off the shelf and onto the floor. This was one of those ancient brown sealed glass ampoule bottles with a handwritten label, dating probably from the 1930s. Clever students that we were, we sopped up much of the liquid with paper towels and threw these in the hood. Back then, the hoods were rarely used, partially because they weren't all that effective and partially because there weren't all that many. Nonetheless, within 30 minutes, residents of the Hill area of Boulder just west of the CU campus began reporting a massive natural gas leak. We heard fire sirens and there were gas company trucks all over the place. Someone in the lab had the presence of mind to call the fire department and report our incident. Once we had convinced them that the cause of their problem was our little spill, life in Boulder returned to its usual abnormal state...

3. een of andere vent on January 10, 2007 8:25 AM writes...

The odor threshold of ethanethiol is about 0.2 ppb (depending on the nose). In order let whole Manhatten Island (51.8 km^2) enjoy the smell up to 200 metres and let one mole of air be 22.4 litre; you will need about 5.3 kg. This will cost you about $500 when bought from Aldrich. Using about 50 kg will certainly be satisfactory for causing some real discomfort. Take 500 kg and the streets will be empty for quite some time.

4. Harry on January 10, 2007 9:17 AM writes...

The plant where I worked right out of college had a process that generated methyl mercaptan as a byproduct. We had a condensing system that captured most of the mercaptan, and a scrubbing system that captured the remaining mercaptan from the vents.

The condensate from the condenser was drained into a 300 gallon catch tank, and from there it was pumped into a 5,000 gallon storage tank for further processing.

One very hot summer Sunday (about 110 F) the gauge glass on the catch tank ruptured. To make a long story short, pretty much the entire contents of the catch tank emptied over about a 3 hour period. Process records indicated that we'd lost about 150-200 gallons of relatively pure methyl mercaptan.

The emergency call center was fielding calls from 25 lines away about gas leaks. Unfortunately- I was the designated spokesman for the comapany for that incident. It was a pretty well unforgettable weekend.

Luckily there were no serious injuries and oddly enough, relatively few claims for damages from the surrounding area.

5. Don B. on January 10, 2007 10:10 AM writes...

I expect it (the smell) came from a sewage treatment plant overflow rather than someone dumping 50kg of methyl mercaptan down the sink in the hood.

6. Ben Hemmens on January 10, 2007 11:22 AM writes...

oh yeah, that brings back memories. like when someone was using a few mg of the stuff in a fume hood one floor up and we could smell it in our lab...

it never really bothered me, as a protein chemist i was generally quite happy in the midst if what other people seemed to regard as an intolerable thiol stench.

7. Sleepless in SSF on January 10, 2007 11:59 AM writes...

When I was an undergrad, lo these thirty years and more ago, we had a prof who wanted to demonstrate diffusion for a freshman general chemistry class. As he entered the lecture hall, he quietly opened a small vial, set it on the bench and proceeded with his lecture. Several minutes later, noses in the first couple of rows began to wrinkle. Within ten minutes the back row was sniffing and the front row was retching. Deciding that a miscalculation had been made, he dismissed the class and exited the area post haste. On the way back to his office, he heard the sirens and saw the first firefighters and campus police arriving. Having concluded that discretion was the better part of valor he quietly entered his office, locked the door, shut the blinds and hid quietly under his desk until calm returned.

8. anon on January 10, 2007 1:31 PM writes...

The smell actually never got past midtown. Columbia is significantly further north. But who knows where are drains go!