Note 29 — PHILOSOPHICAL JOURNAL. (continued 2)

The cause of this fearful epidemic is still a mystery. The meteorological conditions of the atmosphere, although slightly abnormal, are wholly inadequate to account for its induction. It is most probably induced by some gaseous poison diffused through the atmosphere, but of a nature so subtle that the most delicate analysis fails to detect its presence. According to the experiments of Dr Dundas Thompson of Glasgow, no solid matter existed in the air, but ammonia was obtained from it in the proportion of 0·319 grain of caustic ammonia, or 0·731 grain of carbonate of ammonia, to 1000 pounds of air.