Andrew Crosse, an English country gentleman, in 1837 made the following experiment, which excited much publicity: he mixed two ounces of powdered flint with six ounces carbonate of potassa, fused them with heat, reduced the compound to powder and dissolved it in boiling water, obtaining silicate of potassa. This he diluted in boiling water, slowly saturating with hydrochloric acid. This he then subjected to "a long-continued electric action, through the intervention of a porous stone" (?) in an effort to form crystals of silica. This did not happen, but on the fourteenth day of the experiment, he observed a few minute whitish lumps on the middle of the electrified stone. By the eighteenth day, these had grown and stuck out seven or eight filaments. On the twenty-sixth day, they had become perfect insects, standing erect on a few bristles, which were their tails. On the twenty-eighth day they moved their legs, detached themselves from the stone, and began to move about. Perhaps a hundred insects were thus generated, the smaller having six legs and the larger eight; they were pronounced as belonging to the genus Acarus. Mr Crosse repeated his experiment many times with the same result, as did others, creating countless acari which came unerringly to life, fed, multiplied, and died only (but that without exception) upon exposure to frost. The insects were called Acarus Crossii.