
THE CONSTITUTION OF MATTER ; 
one primordial kind of matter, to which other 
philosophers in intervening years had leaned. 
Again, the atoms of the early philosophers were 
indefinite in point of number, while those of Dalton 
were strictly limited to the number of the different 
chemical elements known to existin histime. Each 
atom was supposed by him to have a weight char- 
acteristic of, and peculiar to, the element to which it 
belonged ; and all were believed to be indestructible. 
Dalton said,! ‘we might as well attempt to introduce 
a new planet into the solar system, or to annihilate 
one already in existence, as to create or destroy a 
particle of hydrogen””—a view which, as we shall 
see, no longer holds good for all of the so-called 
elements. 
But Dalton’s notion of an uncertain number “ of 
elementary principles which can never be meta- 
morphosed one into another by any power we can 
control,” was, in the latter third of the last century, 
gradually being superseded by the view, as Sir 
William Crookes? put it, “that our so-called 
elements or simple bodies are in reality compound 
molecules,” made up by varying combinations of 
some extremely minute primordial element, which, 
confessedly hypothetical, he spoke of as protyde. 
Crookes, however, demonstrated. the actual exist- 
ence of particles very many times more minute than 
the chemical atoms, as constituents of the so-called 
‘cathode rays” —and resulting from the splitting up » 
of gases in vacuum tubes by electricity. 
1* New System of Chemical Philosophy,” 1808. 
2 “ Genesis of the Elements,” Chemical News, 55, 1887, p. 83. 
