542 



PHOSPHORUS PHRENOLOGY. 



heat alow. The phosphates of the alkaline earths 

 are not decomposed when heated with charcoal 

 Before the blowpipe both alkaline and earthy ]>lu>s- 

 phates melt into a vitreous, transparent globule. 

 They are soluble in nitric acid without effervescence, 

 and precipitate from that solution by liiuewater or 

 ammonia. Sulphuric acid decomposes them, and 

 separates the phosphoric acid. The alkaline phos- 

 phates are soluble and crystallizable ; the earthy ones 

 are insoluble. The phosphites are distinguished from 

 the phosphates by appearing luminous when heated 

 before the blowpipe, and by affording, on distilla- 

 tion, a small quantity of phosphorus. They become 

 phosphates on exposure to the air for a little time. 

 Phosphureted hydrogen. This interesting compound 

 of phosphorus and hydrogen exists in the elastic form, 

 and is obtained by combining phosphorus with any 

 substance which, by a resulting affinity, shall enable 

 it to decompose water. Thus, if one part of phos- 

 phorus is heated with ten or twelve of a solution of 

 potash, the alkali exerts this operation, the water 

 present is decomposed, its oxygen combines with 

 one proportion of the phosphorus, forming phosphor- 

 ic acid, which unites with the potash ; the hydrogen 

 of the decomposed water combines with another 

 portion of the phosphorus, producing phosphureted 

 hydrogen. Or lime may be substituted for potash. 

 The distinguishing peculiarity o'f this gas is its high 

 inflammability, in consequence of which it takes fire 

 whenever it is presented to the atmosphere. It can- 

 not with safety be mixed with air in any quantity, 

 from the violent detonation that would ensue, and it 

 is therefore allowed to burn as it escapes from the 

 water, in which the beak of the retort containing 

 the materials producing it is immersed. The pro- 

 ducts of its combustion, as it escapes from the retort 

 into the air, are phosphorous acid and watery vapour, 

 which present at their formation a very singular ap- 

 pearance ; the bubble of gas, as it escapes and in- 

 flames, expands into a horizontal ring of light white 

 vapour, which enlarges in diameter as it rises until 

 it breaks ; this is phosphorous acid, wafted by the 

 aqueous vapour, and it owes this corona form to the 

 eccentric impulse of the explosion. It is supposed 

 that many of those lights which are said to have been 

 seen at night around burying-grounds, and other 

 places, when animal and vegetable substances are 

 undergoing decomposition, arise, in part at least, 

 from phosphureted hydrogen. Bihydruret of phos- 

 phorus is a second compound of hydrogen with phos- 

 R horns, obtained when solid phosphorous acid is 

 eated out of contact with the air ; the oxygen of 

 the water of crystallization present converts part of 

 the phosphorous acid into the phosphoric, while the 

 hydrogen, uniting with a small proportion of phos- 

 phorus, forms this gas. It is not spontaneously in- 

 flammable, but detonates when mixed with atmosphe- 

 ric air and heated to 212. Phosphorus is employed 

 in the arts for the construction of fire-matches, and 

 for the preparation of phosphoric acid. Its use in 

 medicine has been attempted, but its violence is too 

 great to be employed with safety. The phosphates 

 are employed as fluxes, and in the composition of 

 pastes for the imitation of gems. 



PHOTIUS ; a patriarch of Constantinople, cele- 

 brated, about the middle of the ninth century, for 

 the brilliancy of his talents and the depth of his eru- 

 dition. He was a native of Constantinople, and ori- 

 ginally distinguished himself by his learning and 

 ability as a layman ; but, on the expulsion of the 

 patriarch Ignatius, by Bardus, was consecrated to 

 the vacant see, 858. During the succeeding ten 

 years, a controversy was carried on with much 

 acrimony between him and the bishop of Rome, 

 each party excommunicating and anathematizing 



the other ; the consequence of which was the 

 complete separation of the eastern and western 

 (linn lies. Bardas, his patron, being at length taken 

 off by his nephew and associate in the empire, Mi- 

 chael the Third, that prince was in his turn assassi- 

 nated by Basilius, the Macedonian, who then as- 

 cended the throne in 866. But Photius, denouncing 

 him for the murder, was in the following year re- 

 moved, to make way for the restoration of his old 

 enemy Ignatius, and was forced to retire into banish- 

 ment. On the death of that patriarch in 878, Pho- 

 tius, by a flattering exposition of a forged document 

 respecting the genealogy of the emperor, acquired 

 his favour, and, being restored, maintained himself 

 in the patriarchal chair during the remainder of that 

 reign ; but was at length accused, on insufficient 

 grounds, of conspiring against the new sovereign, 

 Leo the Philosopher, who sent him, in 886, into 

 confinement in an Armenian monastery, where he 

 died in 891. This learned and intriguing prelate 

 was the author of a Bibliotheca, containing an ex- 

 amination of 280 writers ; the best edition is that of 

 Bekker, a French translation from which was an- 

 nounced in 1831, in six volumes, octavo; of the 

 Nomocanon, a digest of the ecclesiastical laws, acts 

 of councils, &c., under fourteen heads; a Lexicon of 

 the Greek Language; and numerous epistles. Or 

 the Bibliotheca there are two other editions, that of 

 Vienna, 1601, and that of Rouen, folio, 1653. Of 

 the Lexicon, printed at Leipsic in 1808 (edited by 

 Hermann), there is a more accurate copy in manu- 

 script at Cambridge. The Letters appeared in one 

 folio volume, in 1651. 



PHOTOMETER ; an instrument intended to in- 

 dicate the different quantities of light, as in a cloudy 

 or bright day, or between bodies illuminated in dif- 

 ferent degrees. In Leslie's photometer, the essen- 

 tial part is a glass tube, like a reversed siphon, whose 

 two branches should be equal in height, and termi- 

 nated by balls of equal diameter ; one of the balls 

 is of black enamel, and the other of common glass, 

 into which is put some liquid. The motion of the 

 liquor, which is sulphuric acid, tinged red with car- 

 mine, is measured by means of a graduation ; the 

 zero is situated towards the top of the branch that is 

 terminated by the enamelled ball. The use "of this 

 instrument is founded upon the principle that, when 

 the light is absorbed by a body, it produces a heat 

 proportional to the quantity of absorption. When 

 the instrument is exposed to the solar rays, those 

 rays that are absorbed by the dark colour heat the 

 interior air, which causes the liquor to descend, at 

 first with rapidity in the corresponding branch. 

 But, as a part of the heat which had introduced it- 

 self by means of the absorption is dissipated by the 

 radiation, and as the difference between the quantity 

 of heat lost and that of the heat acquired goes on 

 diminishing, there will be a point where, these two 

 quantities having become equal, the instrument will 

 be stationary, and the intensity of the incident light 

 is then estimated by the number of degrees which 

 the liquor has run over 



PHRAT. See Euphrates. 



PHRENOLOGY ; (from <pjit>, mind, and \o 

 discourse,) the term applied to a science of recent 

 origin, which affects to discover the faculties and dis- 

 positions of man from the inequalities displayed on 

 !iis cranium. It was long ago observed by physiolo- 



sts, that the characters of animals were in a great 

 measure determinable by the formation of the fore- 

 icad.and that the intelligence of the animal, in most 

 cases, rose or fell in proportion to the elevation or 

 prostration of his skull. Lavater, in his system of 

 ihysiognomy, went further than this, and gave to 

 articular shapes of the head certain powers ant? 



