The odours of many flowers, so delightful to our sense of smell, as well as the disgreeable scents of others, are owing to the exhalation of their essential oils. These essential oils have greater or less volatility, and are all inflammable; many of them are poisons to us, as these of Laurel and Tobacco; others possess a narcotic quality, as is evinced by the oil of cloves instantly relieving slight tooth-achs; from oil of cinnamon relieving the hiccup; and balsam of peru relieving the pain of some ulcers. They are all deleterious to certain insects, and hence their use in the vegetable economy being produced in flowers or leaves to protect them from the depredations of their voracious enemies. One of the essential oils, that of turpentine, is recommended, by M. de Thosse, for the purpose of destroying insects which infect both vegetables and animals. Having observed that the trees were attacked by multitudes of small insects of different colours (pucins ou pucerons), which injured their young branches, he destroyed them all intirely in the following manner: he put into a bowl a few handfuls of earth, on which he poured a small quantity of oil of turpentine; he then beat the whole together with a spatula, pouring on it water till it became of the consistence of soup; with this mixture he moistened the ends of the branches, and both the insects and their eggs were destroyed, and other insects kept aloof by the scent of the turpentine. He adds, that he destroyed the fleas of his puppies by once bathing them in warm water impregnated with oil of turpentine. Mem. d'Agriculture, An. 1787, Trimest. Printemp. p. 109. I sprinkled some oil of turpentine, by means of a brush, on some branches of a nectarine-tree, which was covered with the aphis; but it killed both the insect and the branches: a solution of arsenic much diluted did the same. The shops of medicine are supplied with resins, balsams, and essential oils; and the tar and pitch, for mechanical purposes, arc produced from these vegetable secretions.] 185 In sulphurous eddies round the weird dame Plays the light gas, or kindles into flame. If rests the traveller his weary head, Grim MANCINELLA haunts the mossy bed, Brews her black hebenon, and, stealing near, 190 Pours the curst venom in his tortured ear.-- Wide o'er the mad'ning throng URTICA flings Her barbed shafts, and darts her poison'd stings.