P H O 



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PHY 



appears to be furnished with no organs 

 adapted to boring so hard a substance as 

 a rock. When the young are disclosed 

 from the egg, being cast upon the rock in 

 which their mother resides, they bore a 

 hole in it which they enlarge daily, and 

 which they never leave, unless compelled 

 by force. This hole always communi- 

 cates with the water, and is the orifice 

 through which the animal exerts its 

 double siphons. One of these siphons is 

 its mouth, and the other its anal orifice. 

 Poli says they use their foot as an augur in 

 excavating their crypts, the shell revolv- 

 ing upon it as upon an axis. Pholades 

 possess a remarkable degree of phospho- 

 rescent property. 



Fragments of fossils belonging to this 

 genus are found in Essex. 



PHO'LADITE. A fossil or petrified pholas. 



PHOLIDO'PHORUS. A genus of fishes of 

 the Wealden formation that prevailed 

 during the oolitic period, but believed to 

 be now quite extinct. 



PHO'NOLITE. (from <f>ovrj, sound, and 

 XiOoQ, a stone, Gr.) Another name for 

 clinkstone. A felspathic rock, sonorous 

 when struck with a hammer, from which 

 circumstance it derives its name. When 

 the texture of basalt is compact, and its 

 felspar greatly prevails, it passes into pho- 

 lonite ; its colour is generally grey, or 

 greenish-grey. Again, when phonolite 

 has a more earthy texture it passes into 

 claystone. 



PHO'SPHATE. A salt formed by the union 

 of phosphoric acid with a salifiable 

 base. 



PHO'SPHATE OF LIMB. This is found in 

 the bones of animals, and constitutes 

 their base, as well as in the mineral king- 

 dom. It consists of lime 59-0, phospho- 

 ric acid 41-0. It is destitute of taste, 

 insoluble in water, and not affected by 

 exposure to the atmosphere. Exposed to 

 a very high temperature it becomes soft, 

 and is converted into a white semitrans- 

 parent enamel, or rather porcelain. Hu- 

 man bones, according to Berzelius, con- 

 tain 51-04 of phosphate of lime, and the 

 enamel of teeth, according to Mr. Pepys, 

 is composed of 78 per cent, of it. Sul- 

 phuric, nitric, muriatic, fluoric, aad 

 several vegetable acids are capable of 

 more or less decomposing phosphate of 

 lime. Mineral phosphate of lime contains 

 several species, namely apatite, asparagus 

 stone, &c., which are described under 

 their several names. 



PHOSPHORESCENCE OF THE SEA. This 

 luminous appearance of sea-water arises 

 from the presence of immense numbers 

 of microscopic medusae which people 

 every region of the ocean, and, being 

 specifically lighter than the sea-water, 



float in incalculable multitudes on its 

 surface. 



PHOSPHORESCENT. Emitting light in the 

 dark without sensible heat. 



PHO'SPHORITE. Amorphous phospate of 

 lime. The chaux phosphatee terreuse of 

 Haiiy ; phosphorit of Werner ; phospho- 

 rite of Jameson. A variety of apatite, 

 with commonly an earthy aspect : it 

 occurs in masses whose surface often dis- 

 plays mamillary projections. Fracture 

 dull and earthy. Colour white or grey, 

 often marked with spots or zones of a 

 brownish tinge. Specific gravity from 

 2-8 to 3-2. Before the blow-pipe it is 

 infusible, but its powder thrown upon 

 live coals emits a yellowish-green phos- 

 phorescent light. In Spain it forms 

 whole mountains ; it is also met with in 

 Germany. According to Pelletier, it con- 

 tains lime 59'0, phosphoric acid 34'0, and 

 the remainder consists of the carbonic, 

 fluoric, and muriatic acids, with a trifling 

 portion of silex and oxide of iron. 



PHO'SPHORUS. (0wo-06pvc;, Gr. phosphorus, 

 Lat. phosphore, Fr.) One of the fifty- 

 five simple or elementary substances, and 

 belonging to that sub-division termed 

 non-metallic. Phosphorus is principally 

 known as entering into the chemical com- 

 position of animals. As a component 

 part of minerals, phosphorus is rare ; 

 but there must be some amount of it 

 entombed in fossiliferous rocks. Phos- 

 phorus is never found pure in nature, 

 and is only to be obtained from organic 

 matter by elaborate chemical processes. 

 It is yellow, and semi-transparent ; re- 

 sembling wax in softness, but more cohe- 

 sive and ductile. Specific gravity 1'77. 

 Its affinity for oxygen is so great that it 

 burns spontaneously in the atmosphere. 

 It should always be kept in bottles filled 

 with water, and well corked. 



PHYLLA'DE. The name given by D'Au- 

 buisson, and the French geologists, to 

 clay-slate. 



PHY'SALITE. A variety of prismatic to- 

 paz, of a greenish-white colour. It occurs 

 in coarse granular concretions, having a 

 low degree of lustre. Edges feebly trans- 

 lucent. It consists of alumina 57-75, 

 silica 34-30, fluoric acid 7'82. It is 

 found at Finbo, in Sweden, and at Alten- 

 berg, in Saxony. 



PHY'LLITE. (from $v\\ov, a leaf, and 

 XiOoe, a stone, Gr.) A petrified leaf. 



PHYSICAL, (physique, Tfr.fisico, It.) Re- 

 lating to nature or to natural philosophy ; 

 not moral ; pertaining to material things. 



PHYSICS, (from ^ixrig, nature, Gr.) Taken 

 in its most enlarged sense, comprehends 

 the whole study of nature ; but in the 

 usual acceptation of the word, that branch 

 of science which treats of the properties 



