Nevertheless, in view of the greater ease of visualization of all the values of this quantity corresponding to successive values of are given in Table X. Fig. 5 shows the graph obtained by plotting the values of , against for the first 51 drops of Table X, and Fig. 6 shows the extension of this graph to twice as large values of and . It will be seen that there is not the slightest indication of a departure from a linear relation between and up to the value , which corresponds to a value of of .4439 (see drop No. 58, Table X). Furthermore, the scale used in the plotting is such that a point which is one division above or below the line in Fig. 5 represents in the mean an error of 2 in 700. It will be seen from Figs. 5 and 6 that there is but one drop in the 58 whose departure from the line amounts to as much as 0.3 per cent. It is to be remarked, too, that this is not a selected group of drops, but represents all of the drops experimented upon during 60 consecutive days, during which time the apparatus was taken down several times and set up anew. It is certain, then, that an equation of the form (15) holds very accurately up to . The last drop of [Pg 114] Fig. 6 seems to indicate the beginning of a departure from this linear relationship. Since such departure has no bearing upon the evaluation of , discussion of it will not be entered into here, although it is a matter of great interest for the molecular theory. Attention may also be called to the completeness of the answers furnished by Figs. 5 and 6 to the question raised in chap. IV as to a possible dependence of the drag which the medium exerts on the drop upon the amount of the latter’s charge; also, as to a possible variation of the density of the drop with its radius. Thus drops Nos. 27 and 28 have practically identical values of , but while No. 28 carries, during part of the time, but 1 unit of charge (see Table X), drop No. 27 carries 29 times as much and it has about 7 times as large a diameter. Now, if the small drop were denser than the large one, or if the drag of the medium upon the heavily charged drop were greater than its drag upon the one lightly charged, then for both these reasons drop No. 27 would move more slowly relatively to drop No. 28 than would otherwise be the case, and hence for drop No. 27 would fall below for drop No. 28. Instead of this the two fall so nearly together that it is impossible to represent them on the present scale by two separate dots. Drops Nos. 52 and 56 furnish an even more striking confirmation of the same conclusion, for both drops have about the same value for and both are exactly on the line, though drop No. 56 carries at one time 68 times as heavy a charge as drop No. 52 and has three times as large a radius. In general, the fact that Figs. 5 and 6 show no tendency whatever on the [Pg 115] part of either the very small or the very large drops to fall above or below the line is experimental proof of the joint correctness of the