M. Marggraff hath also published a process for making Phosphorus, and assures us, that by means thereof we may obtain in less time, with less heat, less trouble, and less expence, a greater quantity of Phosphorus than by any other method. His operation is this: He takes two pounds of Sal Ammoniac in powder, which he mixes accurately with four pounds of Minium. This mixture he puts into a glass retort, and with a graduated fire draws off a very sharp, volatile, urinous spirit. We observed in our theoretical Elements, that some metallic substances have the property of decomposing Sal Ammoniac, and separating its volatile Alkali; concerning which phenomenon we there gave our opinion. Minium, which is a calx of lead, is one of those metallic substances. In this experiment it decomposes the Sal Ammoniac, and separates its volatile Alkali; what remains in the retort is a combination of the Minium with the Acid of the Sal Ammoniac, which is well known to be the same with the Marine Acid; and consequently the residue of this operation is a sort of _Plumbum corneum_. The quantity thereof is four pounds eight ounces. Of this he mixes three pounds with nine or ten pounds of urine, that has stood putrefying for two months, evaporated to the consistence of honey. These he mixes by little and little in an iron pan over the fire, stirring the mixture from time to time. Then he adds half a pound of charcoal-dust, and evaporates the matter, kept continually stirring, till the whole be brought to a black powder. He next distils the mixture in a glass retort with degrees of fire, which he raises towards the end so as to make the retort red-hot, in order to expel all the urinous spirit, superfluous oil, and ammoniacal salt. The distillation being finished, there remains nothing in the retort but a very friable _caput mortuum_. This remainder he pulverises again, and throws a pinch thereof on live coals, thereby to discover whether or no the matter be rightly prepared, and in order for yielding Phosphorus. If it be so, it presently emits an arsenical odour, and a blue undulating flame, which passes over the surface of the coals like a wave. Being thus assured of the success of his operation, he puts one half of his matter in three equal parts, into three small earthen German retorts, capable of holding about eighteen ounces of water a-piece. These three retorts, none of which is above three quarters full, he places together in one reverberatory furnace, built much like those we have described, except that it is so constructed as to hold the three retorts disposed in one line. To each retort he lutes a recipient something more than half full of water, ordering the whole in such a manner, that the noses of his retorts almost touch the surface of the water.