COMMENTARY. As Dr. Coray’s account of the _Nitrum_, _Aphronitrum_, and _Spuma nitri_ of the ancients is of high authority, we are induced to give it in his own language literally translated. “The nitrum of the ancients was not that substance which modern chemists call by the name (nitre or nitrate of potass), being a composition of nitric acid and a vegetable alkali, but that which is called natron, being a native combination of carbonic acid and an alkali (natron or native carbonate of soda.) And they called the harder and more stony lumps nitrum or litrum, and the more spongy and softer aphronitrum or aphrolitrum; and spuma nitri or litri, the superficial efflorescence of the nitrum and floury part, which was easily scraped off.” (Ad Xenoc. et Galen. de Al. ex Aquat.)—From this account it appears that the firmer and harder lumps of the native carbonate of soda were called nitrum; the softer and more spongy pieces aphronitrum, and those kinds which had a bright florid appearance externally and readily crumbled down into a powder, the spuma nitri. Dioscorides gives a more lengthy account of its medicinal properties than either Galen or our author, not only recommending it externally as a stimulant and discutient application to various cutaneous diseases and the bites of mad dogs, but also internally as an antidote to poisonous mushrooms, buprestis, bull’s blood, &c. (v, 129.) Serapion has a very interesting chapter on nitrum and aphronitrum, but it is in a great measure made up from Dioscorides and Galen (c. 411.) For a further account of the ancient nitrum, see under _Litrum_ in this section. We may just mention in this place that the aphronitrum would appear to have been merely _Afrum nitrum_, that is to say, a variety of the nitrum or natron found in Africa. Ἀχρὰς, Pyrum silvestre, _the Wild Pear_; its properties are like those of the common pear, but more intense. It therefore agglutinates large wounds. * * * * * COMMENTARY. Dioscorides mentions that it is a species of wild pear. He recommends it as an antidote to mushrooms. (i, 168.) Serapion and Mesue give it the same character. Ἀψίνθιον, Absinthium, _Wormwood_; it is heating in the first degree, but drying in the third, being possessed at the same time of astringent, bitter, and acrid qualities. It therefore evacuates bilious humours in the stomach by the bowels and by urine. But in collections of phlegm it is of no service, owing to its astringency. The juice of it is much hotter than the herb itself. * * * * *