Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/239

 PHO

PHO

Mr. Homberg, who was the inventor of it, gives the method of" preparing it m the following manner : take four ounces of human dung newly made, mix it with the fame quantity o( roach alum grofsly powdered; put the mixture into a final] iron ladle, capable of holding about a pint ; fet it over the fire ' in a chimney, and it will melt together, and become as fluid as water ; let it boil gently over a fmall fire, continually Sirring it with an iron fpatula, till it is dry : it will then be difficult to ftir, but' it muft be kept ftirring about, and all the lumps it runs into muft be broken, and what adheres to the fides of the ladle ftirred in and b ended with the reft : this muft be conti- nued till it is perfectly dry, and the ladle muft be now and then taken from the fire* and the matter ftirred about in it that it may not grow red-hot. When the whole- is thus per feSly dried, it will ftill be in little lump--, and when cold it muft be rubbud to powder in a metal mortar; it muft then be put into the ladle and fet over the fire again, it will then become a. little moift again, and run into clods. and grumes, but it muft be again ftirred till dry ; when cold it i. to be powdered again, and a third time put into the ladle; and when perfectly dried this time, it is to be laid by in a paper in a dry place; thus is the firft or preparatory operation finifhed.

Take two or three drams of this powder, put it into a fmall matrafs^ capable of holding an ounce and half of water, and which has' a neck fix or (even inches long ; put a paper ftop- per lightly into the neck of the matrafs, then take a fmall crucible of three or four fingers b.eadth high, put two or three fpoonfuls of fand into it, then fet the bottom of the matrafs on the fand, and take care that no part of it touches the fides of the crucible ; fill up the reft of the crucible with fand, and let the whole body of the matrafs be covered with it ; then fet the crucible in one of the common little earthen fur- naces, and make a charcoal fire about it ; for the firft half hour let the coals only reach up to the middle of the cru- cible, but afterwards lay them up to the rim of it; continue this fire about half an hour, or till the powder within the matrafs is red-hot, then pile up more charcoal above the rim of the crucible, and continue this fire an hour, after which let the whole cool. There will arife a large quantity of fumes during the operation, and they will often throw out the ilopper of the matrafs ; but this muff: be replaced, and the fire a little abated in that cafe : when thefe fumes ccafe, the fire may be raifed without hurting the prOcefs, when the crucible is fo cool that it may be taken out of the furnace without burning the hands. This is to be done, and the ma- trafs is to be half raifed out of the fand to make it bear the cold by degrees, and its mouth muft then be flopped clofe- ly with a cork, inftead of its paper ftopper. If, on mak- ing, the matrafs about, the matter falls into powder, it is a proof that the operation has been well performed ; but if it hang together tn form of a cake, 'tis a fign that the matter was not well roafted in the ladle before the putting it into the matrafs.

When the operation has been well performed, and the mat- ter is in powder in the matrafs, pour out a fmall quantity of it on a i iece of paper, and immediately ft op the matrafs again : the powder upon the paper will immediately fume and take fire, burning the paper, and any other combuftible matter that is in the way. If there has been too much of the powder poured out of the matrafs, it muft not be re- turned in again ; for tho' that fhould be done before it be- gins to finoak, yet it will certainly fet fire to all that is in the matrafs j from this it may be eafily (czn alfo, that the matter cannot be emptied out of the matrafs into a phial, but muft always be in the veflel in which the calcination was made. If too much alum be ufed, the powder will not take fire at all : it will be of different colours, according to the vqflTel the firft calcination was made in, and according to the degree of fire that was ufed ; hence it is fumetimes black, fumetimes brown, fumetimes red, green, yellow, or white. It takes fire equally well in the day-time and in the night, and that without the mixture of any other fuoftauce, or without the leaft rubbing, or any other circumftance befide the mere expofure to the air. In this it differs from a'l the other known artificial phsfphori ; for that of urine requires a fmall degree of heat, in order to its burning ; the fma- ihgd'ine pbofp born s requires a conftderable degree; the Bono- nian ftone does not fhine except after having been expofed to the day-light; and air the others require violent rubbing, or a fmart blow to produce their light.

If it be defired to keep this powder good for any time, it muft be put in a dry place where there is not too much heat : the mouth of the matrafs muft be kept clofe f topped, and its body covered with paper ; and the place where it ftands muft not be in too ftrong a light, for the open day-light has been often known to weaken its power ; and, in fine, wholly to fpoil it thro' the glafs. Mem. Acad. Par. 1 7 li.

Fulgurating Phosphorus. See Fulgurating.

Phosphorus metalLrum, a name given by fomc chemifts to a preparation of a certain mineral fpar, which is found in the mines of Saxony and other places, where there is copper. The fpar to be ufed on this occafion is, that kind which is tinged green, and from its, in fome degreej refembling the co- Suppl. Vol. II.

lour of the emerald, is called by fome pfeudofmarKgdus, and by others lapis fmaragdi mineralis. This is to be powdered very fine, and this powder is to be laid on a flat plate of copper, iron, or any other metal : this plate is then to be fet over fome lighted charcoal, and the whole placed in a dark place. The fpar will receive its neceflary degree of beat for fbining long before the metal will, and, confequent- ly, as foon as it begins to mine, the fire is not to be made any brifker. While the plate of metal is held in this degree of heat, and does not appear at allied, the" powder upon it will mine like a lighted coal, and will continue fo for fome time. If it be removed away, and fuffered to cool, it will be fit to repeat the experiment a fecond time with, but its light will not be fo ftrong as before. Phii. Trauf N u Z44. P- 365- Phosphorus of_fulpbur r the name given by the French aca- demicians to a ncw-difcovered fpecies of phofphorus, which readily takes fire on being expofed to the open air- The invention was Mr. Le Fevre's, and the procefs is this : The ingredients are two drams of common fdfbur, half an ounce of fteel filings, ten grains of colophony, and fix drams of common water. Thefe things being all weighed and fet apart, powder about half a dram of the Julphur in a fmall mortar, then add the colophony, and afterwards the remainder of thefulpbur. When this is all reduced to a fine powder, put in the filings of fteel, and rub the whole together till it is fo thoroughly mixed, that the fteel does not appear; but the colour of the whole looks every where uniform and regular : then add about twenty drops of the water; and after beating the whole to- gether add as much more, and continue to do fo till the mafs is of the fubftance of a pafte, but not too moift. Put this pafte into a fmall matrafs that will contain about three ounces, and pour on it more of the water till it fw'im above the furface of the pafte near a quarter of an inch. The matter of the pafte will then break, and appear in form of a granulated powder under the water ; put the matrafs on a fand furnace, but give it no greater heat than that the hand can bear to lie upon the matrafs. When it begins to heat, the mixture will ferment and fwell, and become black; it is then to be ftirred wi h an iron rod, and a little more wa- ter muft be added every quarter of an hour, til! the whole ig ufed. The matter will then be very black and liquid; and it is to be then taken from the fire, and fet by for the whole night. This is the firft and moft eflentia! part of the ope- ration, and in this great care is to be taken that the fire be not too violent ; for if the ftdpbur be burnt, the operation will be fpoiled, and the matter would ferment fo high as to run over at the mouth of the veflel.

To finiili the operation, a little water muft he added to the matter, fo as to fwim over it, and the veflel muft be again fet in the fand, and a ftronger fire given than before ; this is known to be ftrong enough when there is any humid va-

[ pour obferved to arife out of the mouth of the veftel. This fire is to be continued about two hours, that the greater part of

I the humidity may be evaporated; which is known by the iron rod finding fome refiftance when put into the veflel, and the matter it brings up being granulated and folid, or no longer moift ; it muft then be immediately taken from the fire, and the whole is then finifhed. It is neceflary to be very exa£l in this laft critical minute ; for a very little longer

! flanding on the fire will burn the ft'phur, and render all the

1 former care of no effect. The black matter remaining in the matrafs is to be 'taken out, and the fides fcraped clean with an iron rod ; any piece of this that happens to fall up- on a paper takes fire in a very little time, and burns away like the. other, phofphorus. The procefs is a very nice one, but by obferving all the rules here laid down, feveral perfons have fucceeded in making the phofphorus to perfection : the whole intent of the operation feems to be to join together the minute particles of fteel and Julphur \ which when thus joined cannot fail to be very inflammable, and to take fire on receiving the fmalleft humidity from the air to make them ferment.

It cannot but be obferved, that this phofphorus is founded on Lemery's experiments of fteel- and julphur, taking fire to- gether ; but this is a greatly more nice and accurate opera- tion, and a fine improvement on the' original plan, which was only by mixing large quantities of fteel-filings and Jul- phur together into a pafte with water, and burying this in the earth to make it take fire of itfeif, and thus reprefent the natural phaenomena of vulcanos, thunder, lightening, tic. Mem. Acad. Par. 1728.

Phofphorus may be kindled by the effluvia of ele&rtcify, See Phil.' Tranf. N° 4.75. Se&. x«.

PHOSSA, in zoology, a name underftood by fome to exprefs the whole genus of pigeons, but more properly it is the name of one fpecies onlv, the palumbe:, torquatus, or ring-dove. Sec the article Ring dove.

PHOT 1 NX, purvyk, in antiquity, a kind of flute in ufe among the Greeks : it was the fame with the plcgiaula of the Ro- mans. Hofm. Lex. Univ. in voc. PHOXINUS, in zoology, a name given by fome to the ru- tiiusi or ammn touch. Rondekt. de Pifc. See the article Rutilus.

iKk Phos-