_Æpinus’s_ theory of electricity, 115 _Amalgam_, directions for making the best kind of, 126 _Apparatus_, electrical, directions for using the, 68 _Attraction_, electrical, 21 _Aurora Borealis_, how to imitate the, 79 B _Balloons_, inflammable air, 77 _Battery_ electrical, and experiments with it, 28 _Bells_, electrified, 76 _Black lead_, useful for points to lightning rods, 51 _Bladder_, electrified, 93 _Bolognian stone_, artificial, to make, 127 _Bottle director_ described, 65 C _Candle_, to light a, 91 _Cannon_, the electrical, 96 _Cards_ pierced by electricity, 90 _Cavallo_, general laws deduced by him from experiments made with electrical kites, 46 _Cement_, how to make, 125 _Charcoal_ useful at the lower extremity of lightning rods, 53 _Chemical_ theory of electricity, 111 _Clay_ swollen by the electrical shock, 90 _Colours_ changed by the electrical shock, 87 —— experiments on, 87, 88 _Communication_, electrifying by, 15 _Conductors_, of, 6 —— luminous, 82 _Constellations_, to represent the, 101 _Cotton_, electrified, 92 _Cylinders_, of, 9 —— composition for lining, 125 —— plates may be substituted for, 14 D _Dance_, electrical, 75 _Decomposition_ of water by electricity, 103 _Director, bottle_, description of, 65 —— use of, 67 _Discharging_ electrometer, description and use of, 67 —— rod, luminous, 103 _Du Fay’s_ theory of electricity, 109 E _Electric attraction and repulsion_, 21 —— —— —— —— exemplified, 22, 24 —— battery and experiments with it, 28 —— eel, an account of the, 56 —— fly, described, 18 —— light, experiments with, 79 —— spark, 16 _Electric_ spider, 25 _——s_, and phenomena produced by them, 2, 3, 6, 8 —— experiments with charged, 86 _Electrical_ machine described, 9, 13 _Electricity_, the identity of with lightning, 40 —— how it may be applied to the best advantage, 65 —— animal, 55 —— apparatus necessary for, 64 —— atmospheric, danger of making experiments with, 42, 44 —— medical, 63 —— positive and negative, 2 —— various theories of, 108 _Electrometer_ described, 36, 64 —— instructions for using, 37 _Electrophorus_ described, 33 —— experiments with the, 34 _Excited_, what is intended by, 1 _Experiments_, practical rules for making, to the best advantage, 68 —— promiscuous, 94 _Explosion_, the lateral, 101 F _Figures_ made upon glass &c. by means of electricity, 97 _Fountain_, the electrified, 104 _Fractured jar_, how repaired, 70 _Franklin, Dr. his experiment_ with a kite, 40 —— —— —— —— for illustrating his theory of thunder storms, 78 —— his theory of electricity, 116 _Friction_, electric, 65 G _Gibbes Dr._ his theory of electricity, 113