which causes the Stellar Radiations. 219 



pared with his physical force — that force which has sent out 

 the solar radiations many millions of millions of years. Now 

 mark the origin of that solar force. When our sun in its ne- 

 bulous period was expanded less than halfway to the nearest 

 fixed star (aCentauri), it was 666,000,000,000,000,000 times 

 more rare than hydrogen. It was more rare than the highest 

 strata of our atmosphere ; and its repulsive force, latent heat, 

 was in greater proportion than in the last line of the Table of 

 Marsh. That force is indestructible. It cannot be lost. 

 During the condensation of the sun it must be stored up in 

 the solar elements, and pass off as solar radiation. I speak 

 not now of the falling together of the materials of the sun by 

 the force of gravity, and the consequent liberation of heat from 

 that source. That is exceedingly small, not worth counting, al- 

 though it might continue the solar radiations 20,000,000 years. 

 But in the repulsive force which so vastly expanded the 

 nebulous sun we behold only one of the sources of its present 

 power. There was still another and a greater power then resi- 

 ding in our nebulous sun. It was a power great enough to 

 overcome the repulsive force, to condense the nebulous sun to 

 his present liquid condition, and to store up all that infinity of 

 latent heat in the chemical elements of the sun. This para- 

 mount and overcoming power was the chemical force. When 

 all matter was diffused through all space, its condensation 

 could not have been caused from the loss of its heat by radia- 

 tion — in common phrase, by " the cooling of the primitive fire 

 mist." If all space had been thus filled by sensible heat (" fire 

 mist)," then that heat must have remained. It could not radiate 

 away ; for there was no other space where it could go. There- 

 fore we must look to some other well-known cause for the 

 condensation of the primitive solar gases. The only other 

 cause we can think of is chemical action ; and that is an ad- 

 equate, a normal, and a familiar cause. The chemical force, 

 indeed, is the great condensing-power in the universe. Oxygen 

 and hydrogen, when under its influence, are rapidly condensed 

 nearly 2000 times in volume to form water : but the repul- 

 sive force of these gases is not lost ; it is converted partly into 

 heat and light, and partly into cohesion. 



We will now attend to some well-known facts to illustrate 

 how the chemical force may overcome the repulsive force, and 

 imprison in a dense solid or a liquid vast stores of many kinds 

 of physical forces. Gunpowder, nitroglycerine, dynamite, and 

 mercurial fulminating powders are examples. In all these 

 cases the original repulsive force has been overcome and ap- 

 propriated by the chemical force. As being most familiar, Ave 

 will confine our analysis to gunpowder. Its power is stored 



