Chemistry Blog

Jan 24

23 Million Times Slower than Molasses

I have the pleasure of teaching general chemistry II for the first time ever this semester. It is fun to go back and revisit concepts that I have not spent time with since taking general chemistry ~13 years ago. Our first few classes will focus on intermolecular forces (dipole-dipole, London Dispersion, etc.) and some of their macroscopic manifestations. Some examples covered in the book include surface tension, capillary action and viscosity. Searching these topics online led me to my new favorite experiment: the Pitch Drop Experiment.
Pitch Drop

In 1927, Professor Thomas Parnell started the Pitch Drop experiment in which he sought to measure the viscosity of pitch. Pitch is a general term used to describe a highly viscous solid polymer, but this material is often a complex mixture of phenols, aromatic and long chain hydrocarbons. Unfortunately, I could not find the exact composition of the pitch used in this specific experiment, but needless to say this sample does meet the description of a highly viscous material.

The experiment was initiated when Prof. Parnell heated up a sample of pitch and poured it into a conical piece of glass. The pitch was then left to sit for three years, presumably the length of time it needed to cool and completely settle into the cone shape. Immediately after the bottom of the funnel was cut open the pitch came rushing out. Just kidding. The pitch ever so slowly began dripping out of the funnel. How slowly? At a rate of approximately one drop every 10 years. In fact, the most recent drop—the 9th drop ever– fell on April 17th 2014.

The first report on this experiment was published in the European Journal of Physics in 1984. In that manuscript they calculated the pitch (2.3 x 108 Pa s) to be 230 billion times more viscous than water (1.0 x 10-3 Pa s). That means it’s more than 23 million times slower than molasses (5-10 Pa s). The longevity and creativity of this experiment won Thomas Parnell and John Mainstone (the caretaker of the experiment for more than 50 years) an Ig Nobel Prize in 2005. The experiment has also been officially included in the Guinness World Records as the world’s longest continuously running laboratory experiment.

Despite this experiment’s epicness, or maybe because of it, no one has ever been in the room to watch one of the pitch drops fall. The closest anyone has come is a time-lapse video below.

The video is unfortunately anticlimactic. It shows the 9th drop making contact with the 8th drop in the beaker. It isn’t the spectacle of a full ‘drop’ event, but don’t worry. The next occurrence is right around the corner: about 14 years away. In anticipation of this event the University of Queensland has set up three webcams and a continuously streaming live feed on a website called The Tenth Watch. Regardless of where you find yourself, you can keep a constant eye on the experiment as it progresses. And even if you miss the 10th drop, don’t worry, it’s estimated that there is enough pitch in the funnel to produce several more drops over the next 100 years.

Jan 19

New manufacturer of NMR instruments to enter the market

With the exit of Agilent from the NMR instrument market there’s a gap that is in desperate need of filling. Now it looks like a rather unusual group is considering plugging the hole. The company, usual associated with construction but also happens to be the largest manufacture of tyres in the world, is conducting a poll to see whether NMR is a viable option for them.

If you think the chemistry community needs a new NMR instrument manufacturer then please pop over to their website and let your thoughts be known.





The lego NMR instrument now comes with mini figures!



Nov 10

How LCDs work

A little video I put together to explain how liquid crystal displays work, using pasta, stair gates, wool, a hair dryer and some polarizing filters.

Nov 03

How the infamous Yellow Rain investigation has foresaw a drug delivery innovation

By Mark Lorch, University of Hull

The history of science is full of episodes when a seemingly ludicrous theory is ridiculed, but then slowly gathers evidence and support to move from the fringes to the heart of the scientific consensus. Examples include Darwin’s theory of evolution by natural selection, the theory of plate tectonics that control the movement of Earth’s crust and, most recently, the Big Bang theory of the birth of our universe.

All these theories, even though initially mocked, came from respectable academics. It is rare for someone from outside the relevant scientific circles to make a wild stab in the dark and hit upon something that just happens to have a thread of truth to it. But one of these occasions involved a US intelligence officer.

Strange weather

In September 1981 Alexander Haig, the then US secretary of state, made a stunning allegation. He claimed to have evidence that Soviet-backed forces in Vietnam and Laos had been waging chemical warfare on villagers in those countries. A dossier, released shortly after, documented eye-witness accounts – dating back to 1977 – of aircraft spraying areas with a substance that left vegetation littered with small yellow spots. Far worse were reports of horrific symptoms in the exposed populations: people who suffered stomach cramps and vomiting, before dying. This, according to a lab the US government employed, was due to deadly trichothecene toxins present in the yellow material that rained down on the villagers.

The seriousness of the allegations – with the US accusing the Soviets of breaching the Geneva Protocol on the use of chemical weapons – warranted the corroboration of evidence. So samples of the yellow substance were re-tested in labs throughout the world. First military scientists at UK’s Porton Down – and then others – found something surprising: the “yellow rain” contained, primarily, pollen.

Stranger still, the pollen was not complete. It had been stripped of its proteins and contents, leaving a largely empty shell.

Faced with this unexpected finding, Sharon Watson, a US intelligence agent, proposed an explanation for the role of pollen in the mix: that it had been added to aid the dispersal and delivery of the toxins.

As Watson told a Washington press briefing in 1982: the agent initially came down wet, where it was first exposed to the skin. As the toxins were dissolved in a solvent, they were absorbed by the skin very quickly. But as the agent dried, Watson said, “a second aerosol effect” was created from kicking up the particle-sized pollen-like dust, which then lodged in the bronchii of the lung.

Watson told the briefing:

We’ve shown in studies with animals that the internasal LD-50 [the dose lethal to 50% of an exposed population] for the trichothecenes is much lower than we would have expected, and that the trichothecenes, if they come in contact with the mucous membrane, were very rapidly absorbed and are very toxic by this route.

So if you could bring the compound into contact with the mucous membranes of the bronchii, then it’s a very effective way of getting it across. So there are two different ways that the compound is absorbed. It’s [a] very clever, clever mixture.

In short, the intelligence service thought using pollen made the poison a lot more effective.

Local produce

But where did it come from? The cause of the yellow rain turned out to be something much more mundane – honey bee faeces.

Closer inspection showed that the pollen matched that from the flora in the area it was collected and was indistinguishable from local bee poo. The hollowing out of the pollen and lack of proteins was due to the bees having digested the pollen, before it was defecated and left on the leaves. The heavy yellow rain was explained by bees emerging from hives en masse, as they are inclined to do after inclement weather, and defecating (they never do this in their hives).

Meanwhile, the same labs that identified the pollen also failed to find any trace of trichothecence mixed with the pollen, which left the US theory that the yellow rain was a diabolical means of delivering chemical weapons in tatters. Whatever trichothecene was detected may have been naturally occurring, because the fungi that produce it were common in South-East Asia. Some eye witnesses still insist that chemical attacks did occur, but evidence doesn’t seem to support the use of pollen-based warfare as means of delivering those chemicals. Despite this, however, the US government hasn’t retracted its allegations, stating that the issue hasn’t been fully resolved.

The grain of truth

I always found this story with its scientific and political twists quite appealing. Little did I know that I would find myself working on Watson’s crazy idea about delivering chemicals using pollens. It turns out there was a grain of truth in it.

My colleagues and I have been stripping pollen spores down to leave the indigestible shell – to bees and man alike – called an exine. These exines are incredibly tough. They have even been found intact, along with fossils, in sedimentary rock.

We have loaded these empty pollen shells with a variety of compounds including drugs, edible oils and medical imaging agents to see if they can provide a new way of delivering these chemicals to places of interest in the human body.

Our results show that pollen capsules can indeed be used to trap chemicals and deliver them into the body. Exines provide chemical and physical protection to their surrogate cargoes. What’s more interesting is that exine shells appear to assist in the absorption of their contents across a mucous membrane. Just as Watson had suggested they might. The result, then, is a potential drug-delivery device, which was conceived by one US intelligence agent.

The Conversation

Mark Lorch does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.

This article was originally published on The Conversation.
Read the original article.

Oct 01

Peer Reviewed Play List

It’s probably no news to most of use that puns, quotes and lyrics crop  up on a fairly regular bases in titles of research papers. But scientists making humorous and cultural references in their published work does appear to be news in some quarters. A group of Swedish scientist have caught the medias with their 17 year long quest to plant Bob Dylan’s lyrics into their papers. For example who can forget the classic Nature Medicine hit Nitric Oxide and inflammation: The answer is blowing in the wind and or the epic ballad of neuroscience told in  Blood on the Tracks: A Simple Twist of Fate? .

But to really appreciate the research surely you have to listen to the inspiring lyrics whilst reading the papers. So clearly we need a ‘Peer Reviewed Play List‘ to link the science and the music.

So starting with the Dylan tracks and the papers that his lyrics featured in, here’s the play-list and a link to the same on Spotify. Feel free to add any lyrical papers you come across in the comments and I’ll put them on the play-list. Or tweet them using #PeerReviewLyrics.


The biological role of nitrate and nitrite: The times they are a-changin’  (Time’s they are a-changin’  tops the charts with 112 publications listed in Scopus).

Blood on the Tracks: A Simple Twist of Fate?

Nitric Oxide and inflammation: The answer is blowing in the wind 

Dietary nitrate – a slow train coming

Tangled up in Blue : Molecular Cardiology in the Postmolecular era.

Finding MyoD with a little help from my Friends

Another Brick in the Wall: RNAi Screens Identify New Barriers in iPSC Reprogramming

CDK versus GSK-3 Inhibition: A Purple Haze No Longer?

Stairway to heaven: Evaluating levels of biological organization correlated with the successful ascent of natural waterfalls in the hawaiian stream goby sicyopterus stimpsoni 

Take five – Type VII secretion systems of Mycobacteria

Sep 26

The Minecraft Chemistry Challenge

Minecraft is an truly awesome game. Think of it as digital lego set in a infinitely explorable world. But its real draw is that is encourages creativity on so many level. Players can build what they like, but also the code is open source, allowing creative coders to fiddle with rules and resources in the game. The result is a multitude of modifications (or mods in Minecraft parlance).


There are mods for every taste, including those who favour a spot of virtual  chemistry, in the form of Minechem. It allows for some surprisingly sophisticated chemistry. With a range of devises and tools everything in the world can be broken down into elements, and then reacted together to yield an incredible array of compounds.

As fun as Minechem is, my favourite mod of the moment is Printcraft. This allows the player to output anything they have built to a file that can be read by a 3D printer. And given that I have just assembled one of these wonderful contraptions (or ‘plastic tat generators’ as my better half prefers to call it), combined with my son’s Minecraft addiction means that my house is now slowly being invaded by virtual buildings turned real.

So I think I need something more meaningful to do with it. And so over to you. Build me something! Build me something original that’s related to the chemical sciences, be it useful, interesting or just plain cool. And I’ll 3D print (and send the designer) the best ones.

So here are the rules:

1) Construct something related to the chemical sciences in Minecraft, using the official printcraft server (use Minecraft 1.7.8)

Alternatively you can download the sever and run it locally or use the one I’ve set up (connect to IP using Minecraft 1.6.4)

2) Upload the STL file ,that printcraft spits out, to Thingiverse and tag it with 3DMineChem.

3) Add a link to your Thingiverse file in the comments below.

Lets see what we can come up with shall we?

P.S My ulterior motive is that I’m trying to come up with an Minecraft/chemistry workshop for school children and I need some inspiration and some beta-testers of my server.

Older posts «