THE FORCES OF INORGANIC NATURE. 229 



great law, that in all combinations effected through the simultaneous decomposi- 

 tion of compound substances, the heat evolved in the case is equal to the differ- 

 ence between these //z/j and minus quantities. It is ihe resultant of that which is 

 given off by the combinations, and that which is appropriated in the decomposi- 

 tions. 



Let us not forget, that in all these chemical changes, heat is as much a factor, 

 as measurable a factor, and a factor as definite in its operations, as any other 

 element known in chemistry. Yes more, every law in chemistry results more 

 from it than from any other element. 



In combustion we have dissolutions and chemical combinations. Ordinarily 

 oxygen combines with the matter said to be consumed. The oxygen going 

 into the new combination surrenders a portion of its heat. Hence the heat of 

 combustion. And in perfect accord with our theory, we have this rule, that in 

 ordinary cases the heat of combustion is proportionate to the amount of oxygen 

 required in the burning. If the combustion is of two gases, as oxygen and hy- 

 drogen, they both surrender portions of their heat. Hence the intense heat in 

 the case. The heat of combustion is of Uke origin with the heat in other cases of 

 chemical recomposition. Here the same law prevails. The difference is in this 

 alone, that the conditions here are such as to produce luminosity. The reader 

 will see how perfectly all this harmonizes with the theory here advanced. 



Again, as all solid substances can be vaporized, or decomposed and their 

 elements thrown into gaseous form, as this can only be done by means of heat, 

 and as in every case, in the process, a definite amount of heat becomes latent, 

 these gases may be regarded as composed of matter and heat. We have the 

 heavier gases, and the lighter. We know that the heavier gases contain more 

 matter, and the lighter gases less. The lightest gas known to us, hydrogen, is 

 fourteen and a half times lighter than the air, yet it contains matter, being one 

 of the constituents of water. 



Beyond hydrogen our observations are limited. The substances that lie 

 beyond are too subtle for us. Yet there are, doubtless, lying in this region sub- 

 tle gases unknown to us. Beyond al', and crowning all, we have the rays that 

 come to us from the Sun. By the solar spectrum these are divided into heat-rays, 

 color-rays, and chemical-rays. Analogical reasoning may lead us to suppose that 

 these chemical-rays are composed of matter and heat. For not only do they 

 behave like other chemical elements, but, like the gases, they can be made to 

 yield their heat, latent heat, to yield it in great quantity. So electricity lying 

 somewhere, as a half-way point between hydrogen and the chemical-rays, is com- 

 posed of heat and matter, the heat latent till disengaged. Returning to the spec- 

 trum, passing on beyond the chemical-rays, and the color-rays, we have the heat- 

 rays : the heat here being more intense. In the color portion of the spectrum 

 the red is hotter than the yellow, the yellow hotter than the green, the green 

 hotter than the blue, the blue hotter than the violet, and the violet hotter than 

 the chemical-rays. These color-rays, like the chemical, can be thrown into heat. 

 Then in the color-rays also, there is latent heat. Now if the analogy holds good, 



