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ATOMS WITH S3

a collision, since it would give one atom in a molecule a great
velocity relatively to the other, would tend to dissociate the
molecule Into atoms and produce positively charged atoms
rather than molecules.

The maximum number of charges carried by a multiply
charged atom does not seem to be related to any chemical
property of the atom such as Its valency, but to depend mainly
on the atomic weight; thus mercury, the most massive atom
on which observations have been made, can have as many as
eight charges, crypton atomic weight (82) four or five, argon
atomic weight (40) three, neon atomic weight (20) two, nitro-
gen atomic weight (14), and oxygen (16) two, perhaps in rare
cases three, helium also occurs with two charges; the multiple
charge has been found on the atoms of all the elements tested
with the very suggestive exception of hydrogen : no hydrogen
atom with more than one charge has ever been observed,
though as the hydrogen lines occur practically on every plate
more observations have been made on the hydrogen lines
than on those of any other element

When there are on the plates lines corresponding to atoms
of the same element with one, two, three charges, then the
larger the number of charges the fainter the line. Judging
from the intensity of the lines we should conclude that the
number of multiply charged atoms is only a small fraction of
the number with one charge. The ratio of the number of
atoms which have only one charge to that of those which have
two or more charges is very variable and depends on conditions
which are not yet fully understood. For example in the case
of the carbon atom this ratio seems to depend to a very great
extent on the type of gaseous carbon compound in the dis-
charge tube. With some hydrocarbons the doubly charged
carbon atoms are relatively much brighter than with others.
Again, in the case of oxygen I have found that the purer the



	*ATOMS WITH* S3 a collision, since it would give one atom in a molecule a great velocity relatively to the other, would tend to dissociate the molecule Into atoms and produce positively charged atoms rather than molecules. The maximum number of charges carried by a multiply charged atom does not seem to be related to any chemical property of the atom such as Its valency, but to depend mainly on the atomic weight; thus mercury, the most massive atom on which observations have been made, can have as many as eight charges, crypton atomic weight (82) four or five, argon atomic weight (40) three, neon atomic weight (20) two, nitro- gen atomic weight (14), and oxygen (16) two, perhaps in rare cases three, helium also occurs with two charges; the multiple charge has been found on the atoms of all the elements tested with the very suggestive exception of hydrogen : no hydrogen atom with more than one charge has ever been observed, though as the hydrogen lines occur practically on every plate more observations have been made on the hydrogen lines than on those of any other element When there are on the plates lines corresponding to atoms of the same element with one, two, three charges, then the larger the number of charges the fainter the line. Judging from the intensity of the lines we should conclude that the number of multiply charged atoms is only a small fraction of the number with one charge. The ratio of the number of atoms which have only one charge to that of those which have two or more charges is very variable and depends on conditions which are not yet fully understood. For example in the case of the carbon atom this ratio seems to depend to a very great extent on the type of gaseous carbon compound in the dis- charge tube. With some hydrocarbons the doubly charged carbon atoms are relatively much brighter than with others. Again, in the case of oxygen I have found that the purer the