Exp. 1. \Vhen six equal globes of 2 inches in diame ter were in one line and electrified, and then examined in the balance, Coulomb obtained the following results : Density of the first is to that of the second as 143 to 100. Density of the first is to that or the third as 156 to 100.
Hence, the density has been diminished one third from the first globe to the second, and only one fifteenth from the second to the third.
Ex/z. 2. When twelve globes 2 inches in diameter were placed in a row, and examined as before, the electric Density of the first is to that of the second as 1.50 to 1.00. Density of the first is to that of the sixth as 1.70 to 1.00.
Exp. 3. When twenty-four equal globes 2 inches in diameter were placed in a row, the electric Density of the first is to that of the srcond as 1.56 to 1.00. Density of the first is to that of the twelfth Or Middle globe as 1.75 to 1.00.
It follows from these two experiments, that whatever be the number of globes, the mean density varies consi derably from the first to the second, but afterwards very slowly, from the second to the middle globe. At equal distances from the extremities of the row, the electric densities are equal, and therefore the density is always least in the middle.
7. Distribution of Electricity over several unequal Globes.
Exp. 1. \Vhen two globes 2 inches in diameter were placed in contact with one of 8 inches, the quantity of electricity of the small globe most distant from the great one, was to that of the one in contact with the great one as 2.54 to 1.00.
Exp. 2. \Vhen four globes of 2 inches were placed in contact with one of eight inches diameter, the quantity of electricity of the small globe, the most distant from the great one, was to that of the globe nearest the great one as 3.40 to 1.00.
Ez/z. 3. When live globes of 2 inches in diameter, were placed beside another of 8 inches diameter, the ra tio of the density of the fourth globe was to the mean density of the large globe as 2.08 to 1.00.
EXP. 4. \Vhen twenty-four globes two inches in di ameter were placed in contact with one of eight inches, Coulomb compared the twenty-fourth, or the last small globe, with several of the others, and obtained the fol lowing results The quantity of electricity, or mean density of the elec tric matter in the 24th globe, is to that of the 23d -ts 1•19 to 1.01
The quantity in the 2 ith is to that of the 12th as 1.70 to 1.00 The quantity in the 24th is to that of the 2d as 2.10 to 1.0.) The quantity in the 24th is to that of the 1st, or the one in contact with the large globe, as 3 72 to 1.00 The quantity in the 24th is to that of the large globe itself as 2.16 to 1.00 This last result differs very little from that which we have found for the fourth globe, at the end of a line of four globes of 2 inches, in contact w ith a globe of eight inches.
8. Distribution of Electricity on the Suslacc of a Cylinthr.
In the following experiments, Coulomb insulated a cylinder 30 inches long, and 2 inches in diameter ; and having electrified it, lie examined its electrical density in several places by a small circle of gilt paper as before, and obtained the following results : The density of the middle of the cylinder is to that of its extremity as 1.00 to 2 3 The density of the middle of the cylinder is to that of a point 2 inches from the extremity as 1.00 to 1.25 The density in the middle of the cylinder is to that of a point situated in the he misphere, which terminated the cylinder at an inch front its extremity, as . . . 1.00 to 1.80 Hence it follows, that upon the two last inches at the extremity of the cylinder, the electric density is much greater than towards the middle of the cy Under, and that it varies a little from the middle to within 2 inches atilt: extremity.
Exp. I. Having electrified a globe eight inches hi diameter, and made it touch an insulated ball time lines in diameter, Coulomb found its electrical force to be 154°, or 150° when corrected for the dissi pation. He then quickly touched the eight-inch globe with the cylinder two inches in diameter, and 3 ) inches long, and upon withdrawing the cylinder, he examined its electricity by the small ball as former ly, and found it to be 68°. Hence 150° of electricity were reduced to 68° by the contact of the cylinder, which therefore took 82° from the electricity of the globe, leaving it only 68°. The quantity of elect•i fluid, therefore, in the cylinder, is to that in the globe as 82 to 68, or as 1.21 to 1.00. Now, the superficial area of the globe is to that of the cylinder as 60 is to 6 t ; consequently, the mean density of the electric 1.21 .