in the Supplement.

Noxious Insects; Means of destroying them, or pre- venting their Increase. The following remedies we find collected in the Gentleman's Magazine for October 1792.—Of those substances which have been generally observed to be efficacious in driving away or in destroy- ing insects, mercury, and its various preparations, may be reckoned one of the most generally useful. Sulphur is also useful. Oils of all kinds have been often and de- servedly recommended. Tobacco is not less remarkable for its utility. Of the application of these in order.

1. Mercury is known to kill or drive away lice from the human body; and it may probably be of equal ef- ficacy in ridding other animals of their insects. For instance, sheep having a small quantity of mercurial ointment rubbed on their skins, on the sides, between the fore-legs and the body, it may kill or drive away the insect peculiar to them. Sulphur is recommended to be added to the mercurial ointment. Thus not only the insect peculiar to them, but also the scab, may be cured: See the Transactions of the Society for the Encourage- ment of Arts, London, vol. vii. viii. p. 90. In the Transactions of the same society, vol. vi. p. 59. Mr Airway directed that, in the winter, the walls, frames, &c. of his green and hot-houses should be well washed with the following mixture: Take of corrosive subli- mate mercury four ounces, and dissolve it in two gal- lons of water. These houses had been greatly infested with red spiders and ants. After having been washed with the above mixture, neither were to be seen next summer. This wash may be used on old garden-walls, and to the roots of fruit-trees infested with insects, if made weaker. It may destroy the tender leaves of plants, though not the roots. This wash will effectually destroy that disagreeable insect the bug, and all other