MATTER 15 



supposed to exist in matter, is minus 273 °C, so that a 

 temperature has been reached only 48 °C above the 

 absolute zero. 



It has been found that gases can not be liquefied 

 and solidified by the application of any amount of 

 pressure, however great, unless at the same time 

 their temperature be reduced below the critical point. 

 Pressure is, therefore, only a secondary factor in 

 liquefying gases. 



I have stated that there are about seventy elements 

 known to the chemist, and that an element cannot be 

 separated into two or more kinds of matter. 



There is some evidence to indicate that the ele- 

 ments are compounds. The fact that the so-called 

 elements generally give many lines in the spectrum, 

 instead of giving a single line, would seem to indicate 

 that an element is not composed of homogeneous 

 material, and the fact that the chemical action of an 

 element varies under different circumstances in re- 

 markable ways, as, for example, carbon in the hydro- 

 carbon compounds has been regarded as evidence 

 that elements are really compounds. 



On the other hand, it has been claimed that all 

 elements have probably been derived from one orig- 

 inal form of matter, which Professor Crookes calls 

 protyle. From this original stuff, "fire-mist," the 

 elements, as we know them, have been evolved in 

 succession, by cooling; the smallest atoms, such as 

 those of hydrogen, having been first formed. 



The numerical relations between the atomic weights 

 as arranged by Mendeleeff, may be regarded as evi- 

 dence of the common origin of elements. 



For all practical purposes, however, the chemist 

 recognizes the seventy elements as such, and this 

 from the fact that he is unable to separate them 

 into simpler forms. 



