From Alan Hickman
I was intrigued by your article on the prospects of inducing a state of hibernation by exposure to hydrogen sulphide (30 April, p 8). Many years ago I worked on a pilot plant making hydrogen sulphide. During that time I had many a lungful of the gas. I remember the symptoms well: depression, indigestion – and insomnia!
Sleaford, Lincolnshire, UK
