---, spark in, 1422.
---- _and hydrogen combined by_ platina plates, 570, 605, 630.
---- ---- spongy platina, 609, 636.
---- ---- other metals, 608.

_Particles_, their nascent state, 658.
---- in air, how charged, 1564.
----, neighbouring, their relation to each other, 619, 624, 657.
----, contiguous, active in induction, 1165, 1677.
---- of a dielectric, their inductive condition, 1369, 1410, 1669.
----, polarity of, when under induction, 1298, 1676.
----, _how polarised_, 1669, 1679.
----, ----, in any direction, 1689.
----, ----, as wholes or elements, 1699.
----, ----, in electrolytes, 1702.
----, crystalline, 1689.
----, contiguous, active in electrolysis, 1349, 1702.
----, _their_ action in electrolyzation, 520, 1343, 1703.
----, ---- local chemical action, 961, 1739.
----, ---- relation to electric action, 73.
----, ---- electric action, 1669, 1679, 1740.
Path of the electric spark, 1107.
Phosphoric acid not an electrolyte, 682.
_Physiological effects of_ voltaic-electricity, 279.
---- common electricity, 332.
---- magneto-electricity, 56, 347.
---- thermo-electricity, 349.
---- animal electricity, 357.
_Pile, voltaic_, electricity of, 875.
----. _See_ Battery, voltaic.
_Plates of platina_ effect combination, 568, 571, 590, 630.
---- _prepared by_ electricity, 570, 585, 588.
---- ---- friction, 591.
---- ---- heat, 595.
---- ---- chemical cleansing, 599, 605,
----, clean, their general properties, 633, 717.
----, _their power preserved_, 576.
----, ---- in water, 580.
----, _their power diminished by_ action, 581.
----, ---- exposure to air, 636.
----, _their power affected by_ washing in water, 582.
----, ---- heat, 584, 597.
----, ---- presence of certain gases, 638, 655.
----, their power, cause of, 590, 616, 630.
----, _theory of their action_, Doebereiner's, 610.
----, ----, Dulong and Thenard's, 611.
----, ----, Fusinieri's, 613.
----, ----, author's, 619, 626, 630, 656.
_Plates of voltaic battery_ foul, 1145.
----, new and old, 1116.
----, vicinity of, 1148.
----, immersion of, 1003, 1150.
----, number of, 989, 1151.
----, large or small, 1154.
_Platina_, clean, its characters, 633, 717.
---- attracts matter from the air, 634.
----, spongy, its state, 637.
----, _clean, its power of effecting combination_, 564, 590, 605, 617, 630.
----, ---- interfered with, 638.
----, _its action retarded by_ olefiant gas, 640, 652.
----, ----, carbonic oxide, 645, 652.
----. _See_ Combination, Pl