Elements of the Theory and Practice of Chymistry, 5th ed.

by Pierre Joseph Macquer

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.

He begins the distillation with warming the retorts slowly, for about an hour, by a gentle heat. When that time is elapsed he raises the fire gradually, so that in half an hour more the coals begin to touch the bottoms of the retorts. He continues throwing coals into the furnace by little and little, till they rise half way the heighth of the retorts; and in this he employs another half hour. Lastly, in the next half hour he raises the coals above the bowls of the retorts.

Then the Phosphorus begins to ascend in clouds: on this he instantly increases the heat of the fire as much as possible, filling the furnace quite up with coals, and making the retorts very red. This degree of fire causes the Phosphorus to distil in drops, which fall to the bottom of the water. He keeps up this intense heat for an hour and half, at the end of which the operation is finished; so that it lasts but four hours and an half in all: nay, he further assures us, that an artist well versed in managing the fire, may perform it in four hours only. In the same manner he distils the second moiety of his mixture in three other such retorts.

The advantage he finds in making use of several small retorts, instead of a single large one, is, that the heat penetrates them with more ease, and the operation is performed with less fire, and in less time. He purifies and moulds his Phosphorus much in the same manner as M. Hellot does. From the quantity of ingredients above-mentioned, he obtains two ounces and a half of fine crystalline moulded Phosphorus.

M. Marggraff considering, as a consequence of the experiments above related, that a highly concentrated Acid of Sea-salt contributes greatly towards the formation of Phosphorus, proceeded to try several other experiments, in which he employed that Acid in a state of combination with other bases. He mixed, for instance, an ounce of Luna cornea with an ounce and half of putrefied and inspissated urine, and from the mixture obtained a very beautiful Phosphorus.

In short, the several experiments mentioned having thoroughly persuaded him that the Acid of Sea-salt, provided it were highly concentrated, would combine with the Phlogiston as readily as the Vitriolic Acid does, he resolved to try whether he could not make Phosphorus with matters containing that Acid and the Phlogiston, without making use of any urine.

With this view he made a great number of different trials, wherein he employed Sea-salt in substance, Sal Ammoniac, Plumbum corneum, Luna cornea, fixed Sal Ammoniac, otherwise called Oil of Lime. These several substances, all of which contain the Acid of Sea-salt, he mixed with sundry matters abounding in Phlogiston, different vegetable coals, and even animal matters, such as the oil of hartshorn, human blood, &c. varying the proportions of these substances many different ways, without ever being able to produce a single atom of Phosphorus: which gave this able Chymist just cause to suspect, that the Marine Acid, while pure and crude, is not capable of combining with the Phlogiston in the manner requisite to form a Phosphorus; that for this purpose it is necessary the Acid would have contracted a previous union with some other matter; and that the Acid found in urine hath probably undergone the necessary change. M. Marggraff is of opinion that the matter, which by its union renders the Marine Acid capable of entering into the composition of Phosphorus, is a sort of exceedingly subtle vitrifiable earth. The experiments he made upon the Acid of Phosphorus, will shew that his notion is not altogether groundless. M. Marggraff having let some urine, evaporated to the consistence of honey, stand quiet in a cool place, obtained from it, by crystallization, a Salt of a singular nature. By distilling this urine afterwards, he satisfied himself that it yielded him much less Phosphorus than urine from which no Salt had been extracted; and as it cannot be entirely deprived of this Salt, he thinks that the small quantity of Phosphorus, which this urine yielded him, came from the Salt that was still left in it.