The subject of the following communication is a phenomenon unexpected and peculiar; it presents analogies to the phenomena of magnetism and electricity, in so much as it is an exhibition of repulsion; but it is distinguished from these by the absence of attraction, or what is called polarity. So far as I am aware, it is the only known example of repulsion exhibited independently of magnetic or electric excitement, and seems to open up an entirely new field for physical research. On these accounts I was exceedingly desirous to have it brought without delay to the notice of scientific men, and I have to thank our Secretary for-giving me the present opportunity, although at the inconvenience to him of it having to accompany a long and interesting paper on another subject.