1748.  It would be easy, on the same view, to explain hypothetically, how, if one of the rubbing bodies be a conductor, as the amalgam of an electrical machine, the state of the other when it comes from under the friction is (as a mass) exalted; but it would be folly to go far into such speculation before that already advanced has been confirmed or corrected by fit experimental evidence.  I do not wish it to be supposed that I think all excitement by friction is of this kind; on the contrary, certain experiments lead me to believe, that in many cases, and perhaps in all, effects of a thermo-electric nature conduce to the ultimate effect; and there are very probably other causes of electric disturbance influential at the same time, which we have not as yet distinguished.

Royal Institution.  June, 1838.

INDEX.

* * * * *

N.B.  A dash rule represents the italics immediately preceding it.  The references are sometimes to the individual paragraph, and sometimes to that in conjunction with those which follow.

* * * * *

Absolute charge of matter, 1169. ——­ quantity of electricity in matter, 852, 861, 873.  Acetate of potassa, its electrolysis, 749.  Acetates, their electrolysis, 774.  Acetic acid, its electrolysis, 773. Acid, nitric, formed in air by a spark, 324. ——­, or alkali, alike in exciting the pile, 932. ——­, transference of, 525. ——­ for battery, its nature and strength, 1128, 1137. ——­ ——­, nitric, the best, 1138. ——­ ——­, effect of different strengths, 1139. ——­ in voltaic pile, does not evolve the electricity, 925, 933. ——­ ——­, its use, 925.  Acids and bases, their relation in the voltaic pile, 927, 933.  Active battery, general remarks on, 1034, 1136.  Adhesion of fluids to metals, 1038.  Advantages of a new voltaic battery, 1132. Affinities, chemical, opposed voltaically, 891, 904, 910. ——­, their relation in the active pile, 949. Air, its attraction by surfaces, 622. ——­, charge of, 1173. ——­, ——­, by brush, 1434, 1441. ——­, ——­, by glow, 1537, 1543. ——­, convective currents in, 1572, 1576, 1581. ——­, dark discharge in, 1548. ——­, disruptive discharge in, 1359, 1406, 1425, 1526. ——­, induction in, 1208, 1215, 1284, 1362. ——­, its insulating and conducting power, 411, 1332, 1336, 1362. ——­, its rarefaction facilitates discharge, 1375. ——­, electrified, 1443. ——­, electro-chemical decompositions in, 454, 1623. ——­, hot, discharges voltaic battery, 271, 274. ——­, poles of, 455, 461, 559. ——­, positive and negative brush in, 1467, 1472, 1476. ——­, ——­ glow in, 1526, 1530. ——­, ——­ spark in, 1485. ——­, rarefied, brush in, 1451, 1456. ——­, retention of electricity on conductors by, 1377, 1398. ——­, specific inductive capacity of, 1284. ——­, ——­, not varied by temperature or pressure, 1287, 1288. Alkali has strong exciting power in voltaic