1050 Dynamic Theory. 



the case of magnesium vapor, increase of pressure widens the lines of 

 its spectrum and also increases their number. In general, increase of 

 pressure in vapors and gases causes a widening of their spectrum lines. 

 Increase of the temperature of solid bodies increases the kinds of light 

 they emit, but such increase in the temperature of a vaporous or gaseous 

 body does not change the quality of the light. When pressure is in- 

 creased molecules are pressed into moles ; and in vapors that are upon 

 the point of condensation into liquids or solids, the moles are in the 

 greatest variety of size and form. When temperature is increased in 

 solids the moles are in process of disintegration back to molecules. 



The fact that hydrogen marks four disconnected lines for its spec- 

 trum, makes it exceedingly probable that the molecules or moles of 

 hydrogen are of four forms, and that the atom is really compound. 

 The atom of hydrogen is much lighter than that of any other element. 

 Most of the elements also mark more lines on the spectrum ; and so it 

 should be inferred that the atoms of all elements are compound. This 

 is the view taken by Mr. Lockyer a number of years ago, and which 

 he supported by many arguments drawn from spectrum analysis. As 

 pointed out above, this view is demanded by the fact of the differences 

 in the atomic weights of chemical atoms, making it necessary to recog- 

 nize the gravitation unit or atomicule. It is confirmatory of the views 

 given here that compound bodies give spectra of their own, and as pe- 

 culiar and characteristic as those of the so-called simple bodies. The 

 spectra of such compounds as iodide of strontium, or chloride of stron- 

 tium, or bromide of strontium, consist of fluted or channelled spaces 

 and bands, and these increase in number as the bodies are made more 

 dense, just as in the case of simple bodies. 



As observed before, the temperature at which the combinations of 

 atomicules in the formation of the chemical atoms originally took 

 place, was greater than the chemist is now able to reproduce, and so the 

 chemical atoms have not been undone. 



We have every reason to infer that there is no difference between the 

 atomicules in their mass and form, and consequently in their reactions 

 against force. But as soon as they are combined together in the forma- 

 tion of different shaped bodies, their movements under the impulses of 

 force become different. This is a reasonable inference, and is abun- 

 dantly supported by the facts of allotropism, &c. , mentioned in chapter 

 37. In such cases it is evident that new properties or reactions are 

 brought about by a change of form, and occur as soon as such change 

 is effected. 



It is from want of recognition of the essential qualities of form and 

 size of the body moved, in all cases of motion, that has led to the no- 

 tion of discontinuity in the causation of things. The instant a change 



