524 THE POPULAR SCIENCE MONTHLY 



discharge through helium in which there is a strong line, 6, which could 

 be explained by the compound HeH 2 , but, as I have never again been 

 able to get these lines, I do not wish to lay much stress on this point. 

 There is, however, the possibility that we may be interpreting Men- 

 deleefs law too rigidly, and that in the neighborhood of the atomic 

 weight of neon there may be a group of two or more elements with 

 similar properties, just as in another part of the table we have the 

 group iron, nickel and cobalt. From the relative intensities of the 22 

 line and the neon line we may conclude that the quantity of the gas * 

 giving the 22 line is only a small fraction of the quantity of neon. 



Let me direct your attention again to the photograph of the heavier 

 gases in the atmosphere. You will notice that the parabolas correspond- 

 ing to many of the elements start from points which are all in the same 

 vertical line; this indicates that the atoms or molecules which form 

 these parabolas all carry the same charge. Several of these lines, how- 

 ever, do not follow this rule; you will notice, for example, that the 

 neon line has a prolongation which comes nearer than the normal line 

 to the vertical line drawn through the undeflected spot. Measurement 

 of the photograph shows that the neon line begins at a distance from 

 this vertical line which is only half the normal distance; this shows 

 that some of the neon atoms in the positive rings possess two charges 

 of electricity; the majority of them, however, only possess one. If you 

 examine the argon line you will find that it comes even nearer to the 

 vertical than the neon line, in fact, it begins at a distance from the 

 vertical only one third of the normal distance; this proves that the 

 argon atom can have as many as three charges of electricity. If now 

 you examine the krypton line you will find that it comes nearer to the 

 vertical line than even the argon ; its least distance is one fourth of the 

 normal distance, showing that the krypton atom may have as many as 

 four charges. The mercury line comes so close to the vertical line that 

 it is only on large photographs that it can be seen that there is in reality 

 an interval; this interval is only one eighth of the normal interval, 

 showing that mercury may acquire eight positive charges, i. e., that it 

 may lose eight corpuscles. The mercury atom when it is on this line 

 must have only the normal charge, i. e., it must have regained all but 

 one of the corpuscles it previously lost; if it had retained two positive 

 charges it would have been on the line corresponding to the atomic 

 weight 200/2 or 100 : if it had retained 3, or 4, 5, 6, 7, 8 on the lines 

 corresponding to the atomic weights, 200/3, 200/4, 200/5, 200/6, 200/7, 

 200/8 respectively. All these except the last have been detected on the 

 plate. The lines corresponding to the multiple charges on krypton, 

 argon and neon have also been detected. It appears, then, that in a 

 vacuum tube a mercury atom, for example, may be ionized in two ways; 

 in the one way the atom loses one corpuscle, in the other it loses eight. 



