Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 3, 1802).djvu/163

143&#93; MAG ■neration of such vermin. — In hot camates, where the flesh of ani- mals undergoes putrefaction within a tew hours, it will be advisable to cover tJie meat with the leaves of the Swallow-wort (Stapelia va- rie^aia and Jiirs'ita), natives of Africa ; or with those of the Fetid Goose-foot or Orache (Chmopn- diuin olidumj, cither of which pos- sess a very fetid smell, that at- trafts the ovijiarous flies to deposit their eggs on these leaves, mistak- ing thtm for putrid flesh ; but, as the. young brood cannot subsist on vegetable food, they speedily pe- rish. — FuNKE remarks, tiiat a cou- ple of flies, according to a proba- ble computation, may produce in one year, two millions of descen- dants. MAGISTERY, a name given to almost every precipitate obtained by solution, as opposed to calx, which is procured wholly by calci- nation : it is chiefly employed to denote such precipitates as are used in medicine ; for instance, the magistery of bismuth, coral, crabs- eyes, &c. Magistery of Bismuth is a fine powder, prepared by dissolving bismuth in nitrous acid, and pour- ing on It a large (]uantity of pure water, which precipitates the ma- gistery to the bottom of the vessel. Jt is chiefly emploved as a cosme- tic by vthe gay and giddy, on ac- count of the superior beauty and dazzling whiteness which it im- parts ; but it is very pernicious to health, and eventually injures the skin. — See Biswi'Th. AJagisleri/ of' Coral, crabs-eyes, pearl, shells, chalk, and other ab- sorbent matters, is prepared by dissolving any of these substances in the nitrous acid ; when they must be precipitated by li.ed al' MAG [145 kali, and repeatedly v/ash?d in pure water, till the latter is per- fectly tasteless. Alagisf'jiy of Lead is the calx of that metal, dissolved in Aqua-f jrtis, and precipitated witl) filtred salt- water, by which means the powder acuires a beautiful white colour. It is softened by repeated ablu- tions, and then mixed with poma- tums for improving the skin and complexion of the face. — Like all other preparations of lead, this ma- gistery is a slow poison, and will tl'.erefore never be used by thcxse who have the least regard for their health. IMAGNESIA, or Magnesia al- ia, a kind of absorbent earth, flrst discovered in the commencement of the ISth century. Vv'hen pure, it is extremely white, loose, and light, being intusible,asit resists the heat of the most powerful burning lens. This earth, hovvever, easily melts with borax ; and is divested of its flxed air by calcination : in this state, it is less soluble than be- fore, and does not efiervesce with acids, but it may be safely taken intemally. Native magnesia is not found in quantities sufficiently large and pure for general use. It is therefore pre- pared by dissolving separately equal portions of Epsom salt and pearl- ashes, in double their quantity of warm water, when the sediment is to be strained : the two liquids are now to bemixedi adding eight times their proportion of warm water. The whole is suffered to boil a tow minutes, being carefully stirred with a wooden spatula, to prevent the powder from adhering to the bottom of the vessel. Now the li- quid is to stand at rest, till the heat be somewhat diminished, when it should be filtered through a cloth.