PH O

P H O

( 216 )

five or fix parts of olive oil, and then put into a■phial and allowed to Hand for fome little time,without applying heat, a liquid phofphorus isproduced, which, when quite clear (fo that noneof the phofphuret is fufpended in the oil) may-be rubbed on the llcin with perfect fafety, andihines with much more brilliance than the folu-tion of Ample phofphorus in oil. Equal partsof this phoiphuret in olive oil and oil of tur-pentine when fliaken together and poured outof a veflel, gives in the dark the appearance ofa beautiful fhower of fire. p

The eflential oils alio diffolve this phofphuretand produce luminous folutions.

Phofphorus unites with molt of the metals,forming compounds, which are all brittle, andlnoftly of a greyifh-white colour. Thefe phof-phurets may be made either by heating themetal (in fhreds or powder) with a mixture ofphofphoric acid and charcoal; or by projedlingphofphorus on the metal when red-hot. Thephofphorus barns off from mod of the metallicphofphurets by heating in the open air. Theyare individually defcribed under the refpecfivcmetals.

PHOSPHORIC and PHOSPHOREOUSACID.

The product of the combuftion of phofpho-rus (or oxygenation in any other way) is anacid, which, though compofed merely of phof-phorus and oxygen, differs in a notable degree.according as the oxydation is more or lefs com-pleat- When incompleat, the phofphoreous acidis produced; when compleat, the phofphoricacid, fo that of thefe two fubftances, the formercontains more phofphorus or lefs oxygen thanthe latter. Some chemiils have rather fuppofedthat the phofphoreous acid is the phofphoric,bolding fome uncombined phofphorus in folution{in the fame way as the nitrous acid may beconfidered as the nitric, holding diffolved nitrousgas) that is to fay, that all the oxygen of thephofphoreous acid, is combined with a part onlyof the phofphorus, and in the proportions inwhich phofphoric acid is conftituted, and thatthe fuperabundant phofphorus of the phof-phoreous acid is only in loofe combination withthe remainder. Perhaps this is the proper wayof confidering this i'ubjedl, for though the phof-phoreous acid cannot be made by digefting phof-phorus in the phofphoric acid, the former acidmay be converted into the latter by mere heat,yvhich drives off the excefs of phofphorus.

The Piiosphoreous Acid is produced byjfoe flow combuftion of phofphorus in atmof-

» Aecum.

pherical air, or that which is excited at all thecommon temperatures at which phofphorusbecomes limply luminous without burfting intoflame. It may be fafely performed in final 1quantities at any heat below the melting pointof phofphorus. The phenomena attending theflow and the rapid combuftion of this fubltancein common air and in oxygen, have been alreadyfully defcribed.

Phofphoreous acid is conveniently preparedaccording to Pelletier’s method. Inclofe flicksof phofphorus, each in a final! glafs tube, quiteopen at one end, and drawn out to a capillarytube at the other. Arrange any number ofthefe in a glafs funnel, with the fmaller ends ofthe tube downwards, and fet the funnel in anempty glafs bottle. The contact of the airimmediately begins the flow combuftion of thephofphorus, and a luminous vapour arifes fromeach tube. But if this vapour (which is phof-phorized azot in the a£l of union with oxygen)is allowed to difperfe freely in the air, moll ofthe phofphorus would be wafted away and loft ;fo that it is found neceffary to confine it, byfetting the bottle and funnel on a plate with alittle warm water at bottom, and inverting overthe whole a large bell-glafs, with an opening inthe middle, loofely corked, through which fuffi-cient air may be let in from time to time, tomaintain the flow combuftion of the phofphoruswithin. In this way the phofphorus graduallydeliquefees into a liquid acid, which falls indrops through the tube and funnel into theveflel below. About three times the weightof the phofphorus employed may be collected.The ufe of confining each flick of phofphorusin a feparate tube is, to guard againft the dange-rous accident of the whole phofphorus takingfire ; for though a Angle flick of it may beexpofed to any natural temperature withoutkindling, it has been found that when a numberof flicks are heaped together and expofed to theair from 650 to 70*, fo much heat is generatedby the flow combuftion, as to caufe the wholeto inflame, which might be produdlive of themoll ferious confequences.

The acid which drops from the phofphorusin this procefs is the phofphoreous, and is a tranf-parent liquor of the confidence of iyrup, ftreakywhen fhaken, without fmell, and with a ftronglyacid and peculiar tafte. 1 When heated in aretort, it firft thickens by the lofs of its fuper-fluous water, after which a number of bubblesarife to the furface, and break with a whitefmoke, which is luminous in the dark, fmells

* Fourcroy,