PHO
PH A ( 207 )
PHARMACOLITE. * Chaux arfeniatee.Hauy.
The colour of this mineral is fnow-white ; itoccurs in fmall cryftals occafionally prifmatic,but more commonly acicular; fometimes theCryftals are aggregated into bundles, and fome-times into maruilated maffes. Internally it isgliftening, with a filky luftre. Its fra&ure isradiated or divergingly fibrous; it alfo prefentslarge and fmall granular diftincft concretions.The cryftallized varieties are tranllucent. It isvery tender, and eafily frangible.
It is foluble in nitric acid without effervef-cence. By the action of the blow-pipe it difen-gages an arfenical odour, and leaves an invola-tilizable refidue. By the experiments of M.Selb, it was firft afcertained to be a compoundof lime and arfenic acid, with a little cobalt;a. refult which has been fully confirmed by acompleat analyfis of it by Klaproth . b
One hundred grains of this mineral, accordingto the celebrated chemift laft mentioned, lofeby being moderately heated, and without thedifengagement of any arfenical or other odour,or vifible vapour, 22.5 grains, which are waterof cryftallization. The refidue by digeftion innitric acid is diflolved, except 6 grains, whichare a mixture of filex and alumine. The nitrousfolution affords with acetite of lead, a copiousprecipitate of arfeniat of lead, which, whenwalhed and dried, weighed 138 grains, andindicated 46.5 of arfenic acid. The remainingfluid, with the wafhings, was moderately evapo-rated, and treated with a litt.e muriatic acid,to feparate the fmall portion of acetited leadwhich it contained, and was then mixed withfulphuric acid : this produced a large depofitof fulphat of lime, which after being walhedwith dilute fpirit of wine, and heated-to rednefs,weighed 54 grains, and therefore contained 23grains of lime. The refidual liquor being neu-tralized by carbonated foda, and evaporated todrynefs, was rediffolved in water, and leftbehind 0.5 grs. of a blue powder, which tingedborax of a. deep blue colour, and was oxyd ofcobalt. Hence 100 parts of pharmacolite con-tain. 46.5 Arfenic acid
23. Lime0.5 Oxyd of cobalt
6. Silex with alumine
22.5 Water
98.5
, / die firft three ingredients appear to
r , . e OI ? y ones ne ceffary to the conftitution©1 this mineral.
* Brochact II, p. 5*3. k Klap. Analyt.
It has been found near Wittchen, in Swabia ,in a vein of granite, accompanied by heavy fparand gypfum. It has alfo been met with atSt. Marieaux-mines in France .
PHLEGM. This term has long been ufedto fignify the mere watery part which rifesin many compound diftillations. Thus the firftproduct from oil of vitriol when heated, is anacidulous Phlegm.
PHLOGISTON. All that we think it necef-fary to-fay on this merely theoretical fubjeeft,will be found under the article Oxygen .PHLOGISTICATED AIR. See Azot .PHLOGISTICATED ALKALI. SeePRus-
SIAT of Potajh.
PHOSPHORUS. (ICunchel’s)
Phofphorus is a Ample fubftance, much re-fembling wax in confidence, when pure nearlyof the tranl'parency of gum copal, of a colourvarying from amber red to the fainteft: ftraw,highly combuftible, and when oxygenated pro-ducing a ftrong and peculiar acid.
It was difeovered by a German chemift ofthe name of Brandt about 150 years ago, andthe preparation was long kept a lucrative fecretin the hands of a few perfons, but as it wasgenerally known to be prepared from humanurine, and as the method then employed,though tedious and difgufting, was extremelyAmple, it was detected by feveral chemifts,and the real nature of phofphorus has beengradually explained by a vaft number of in-genious and elaborate refearches.
The earlieft mode of preparing phofphorus*was the following: a large quantity (amountingto feveral gallons) of human urine was collected,and after remaining for a time to become putridit was evaporated to drynefs in any fuitableveffel. The refidue confifts of the animal ex-tractive matter and of many falts, (for whichfee the article Urine ) among which are twowith phofphoric acid, the phofphats of foda andof ammonia. This refidue was then mixedwith charcoal in powder, and heated graduallyto low rednefs in an iron pot, by which the ■animal matter was deftroyed, till the mafs .began to fend forth blue luminous vapours..It was then removed into a coated earthenretort with a receiver, and heat applied gra-dually till it reached the utmoft intenfity, duringwhich the phofphorus diftiiled over and partlyconcreted in the neck of the retort, and partlyfell in drops into the receiver. This, whichwas at firft black and foul was purified bymelting, and was formed into fti.cks, whichwere long fold at a very high price as a great