"Keep the water in the vessel as hot as at first, till, on taking out the tube, you see the Phosphorus clean and transparent. Let the clear tube cool a little, and then set it in cold water, where the Phosphorus will congeal as it cools. When it is perfectly congealed, pull out the cork, and with a small rod, near as big as the tube, push the cylinder of Phosphorus towards the mouth of the funnel, where the feculency lies. Cut off the black part of the cylinder, and keep it apart: for when you have got a quantity thereof, you may melt it over again in the same manner, and separate the clean Phosphorus which it still contains. As to the rest of the cylinder which is clean and transparent, if you intend to mould it into smaller cylinders, you may cut it in slices, and melt it again by the help of boiling water in glass tubes of smaller dimensions." _OBSERVATIONS._ This process for making Phosphorus is copied from the Memoirs of the Academy of Sciences for the Year 1737; where it is described by M. Hellot, with so much accuracy, clearness, and precision, that I thought I could not do better than transcribe it, without departing from the author's own expressions, for the sake of such as may not have those Memoirs. We shall take occasion, in these observations, to point out some essential circumstances which I have omitted in the description of the Process, that I might not break the connection between the phenomena that happen in the course of this experiment. It is proper to observe, in the first place, that one of the most usual causes of miscarriage in this operation is a defect of the requisite qualities in the retort employed. It is absolutely necessary to have that vessel made of the best earth, and so well made that it shall be capable of resisting the utmost violence of fire, continued for a very long time; as appears by the description of the process. The retorts commonly sold by potters, and other earthen-ware men, are not fit for this operation; and M. Hellot was obliged to send to Hesse-Cassel for such as he wanted.