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Cornstarch and water mixtures

Dear Reader,

Recently my daughter’s boyfriend showed me a mixture of cornstarch and water which has interesting mechanical properties. The simple mixture of the two was similar to that of boron oxide crosslinked silicone oil which is known as “silly putty”. It was fun to play with in the kitchen sink.

I was also asked by my daughter about the pharaoh’s serpent which I had to respectfully decline to do at home as I do not want to handle mercury thiocyanate in my home. When this salt burns it forms a long tail from a small volume of fuel. This experiment is likely to form a lot of  mercury vapor and the “snake” is likely to contain small droplets of mercury.

I have seen an even more crazy experiment, which is described as a “portal to hell“, I am not sure what the point of doing such an experiment in front of the students is. It appears to be a combination of ammonium dichromate and mercury thiocyanate. Looking at the experiment it looks like a rather crazy overgrown indoor firework, I just fail to see the point of doing it as it will not teach the students anything other than the fact that the chemistry academic knows how to make exciting looking effects appear in the lab.

A dramatic experiment which is known as Liebig’s blue devil or the “barking dog” is one which I would be uneasy about doing, it is a combination of carbon disulfide and nitric oxide which burns at a very high speed forming blue light and marking a barking noise as the reaction front travels through the mixture. I would strongly advise my readers not to attempt this experiment, it is interesting that Liebig was hurt when the experiment went wrong, he was hit in the torso by flying debris. His life was saved by his snuff box which prevented a shard of glass from striking his femoral artery. I would like to suggest that anyone who wants to do this experiment should first consider what can they gain from doing this experiment, and secondly how they would be able to cope with an accidental explosion. If I was to do the barking dog, I would be wearing eye protection, hearing protection, heavy gloves to protect my hands and fire retardant clothing and I might consider wearing a bullet resistant vest or jacket to protect against flying debris.


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