P H O
PH O
( 224 )
It is compofed, according to Vauquelin, of49.43 per cent, of potafh; 39.47 of phofpho-reous acid; and 11 of water of cryftallization.
Phosphite of Soda.
This fait is prepared like the laft-mentioiied,but chiefly by the help of evaporation. Twoparts of cold water diffolve it, and fomewhatlets of boiling. The folution gently evaporated,depofits the fait generally in the form of featherycryftals like fal-ammoniac.
It is compofed of 23.68 of foda; 16.32 ofphofphoreous acid; and 60 of water.
Phosphite of Ammonia.
This fait has a ftrong pungent tafte, cryftal-lizes in long tranfparent needles that climb thefides of the veflel that contains the folution; isioluble in two parts of cold water, and muchlefs of boiling.
When heated before the blow-pipe on ametal fpoon, it fwells, boils, and in a fewfeconds gives out a great quantity of phofphu-retted hydrogen gas, which takes fire in the air,with its ufuai appearance of a circular wreathof fmoke. Diltilled in a retort, liquid ammoniais firft difengaged, which is fucceeded by fub-phofphuretted hydrogen, which is luminous inthe air, but does not inflame like the former,and finally pure phofphoric acid is left in theretort.
This fait added to nitrat of mercury precipi-tates a white phofphite of mercury, which turnsgrey in the light.
Phofphite of ammonia is decompofed by the’fixed alkalies, and alkaline earths, which unitewith the acid and difengage ammoniacal vapours.
It is compofed of 51 per cent, of ammonia,2 6 of phofphoreous acid, and 23 of water.
Phosphite of Lime.
Phofphoreous acid added to lime water formsa white precipitate, which is the phofphite oflime. This is infoluble in water except withan excefs of acid, in which cafe it may beobtained by evaporation in hard minute cryftals.This fait is decompofed by molt of the mineralacids, and by thofe vegetable ones that pro-duce an infoluble fait with lime, fuch as theoxalic, citric, and tartareous. Phofphite oflime is compofed of 51 per cent, of lime; 34 ofacid; and 15 of water.
Phosphite of Barytes.
This, like the former is infoluble in waterwithout addition, though not absolutely fo, fincewhen digefted in water, lime water added tothe clear liquor caufes a cloudinefs, owing tothe decompofition of the phofphite of barytes,•and formation of phofphite of lime. The folu-
bility of phofphite of barytes much increafesbyan excefs of acid. This fait is decompofed byoxalic acid, which forms a cryftalline depofit ofoxalat of barytes after remaining with it fora time.
When phofphite of barytes is heated by theblow-pipe it becomes luminous, as all thephofphites do, but in this inftance the light isl'o dazzling that the eye cannot fafely hear it.
It is compofed of 51.23 per cent, of barytesi41.77 of phofphoreous acid; and 7. of water.
Phosphite of Magnesia.
This fait, like the laft, is fcarcely folubleexcept with excefs of acid. It is compofed of20 of magnefia; 44 of acid; and 36 of water,The fixed alkalies and the alkaline earths de-compofe it entirely, but ammonia only partially,and forms with the remainder a triple fait.
PHOSPHORUS Cantons £>ee
PHOSPHORUS Baldwins J Phosphori.PHOSPHORI.
In the preceding defeription of Kunckel’sphofphorus we have mentioned that when ex-pofed to the air at the common temperature, itgives out a very confiderable quantity of lightwithout any fenfible emifiion of heat. Nowthere are many fubftances which, however dif-ferent from common phofphorus in other re-flects, agree with it in prefenting the abovephenomenon under particular circumftances,on which account they are all popularly clafledtogether under the general term Phofphori. Ofthefe we fhall now proceed to mention theprincipal fa£ts that have been as yet difeovered.
There are three leading divifions of phofpho-refeent fubftances.
The firft comprehends thofe which require aprevious expofure to the folar or other light inorder to become luminous; whence they arecalled Solar phofphori.
The fecond includes thofe which without anyneceflary previous expofure to light becomeluminous when moderately heated; Phofphorifrom heat.
The third includes thofe fubftances, belong-ing to the animal and vegetable kingdoms,which emit light fpontaneoufly at the commontemperature without the neceftity of previousexpofure to light; Spontaneous phofphori.
§ 1. Solar phofphori.
A cafual difeovery by Vincenzio Cafcariolo,.a fhoe-maker of Bologna, about 1630, was thefirst circumftance that attracted the notice ofphilofophere to this curious fubjedt. Thisman being in queft of fome alchemical fecretwas induced to calcine a parcel of Bolognian