PRIESTLEY'S DISCOVERY OF OXYGEN GAS. 397 



place, not through present and incessant interventions, but in obe- 

 dience to ancient law ? I recall what we all witness as respects the 

 social condition of man, that, according as he advances in intellect, he 

 lives under self-imposed rules, and that his reverence for law is the 

 measure of his civilization ; that it is the pride of that civilization to 

 put in the place of an autocrat, dispensing instant rewards and pun- 

 ishments with his own hands, the ideal majesty of the law, which deals 

 out inflexible justice to the good and evil, and makes no distinction of 

 persons; and, reasoning in this manner, from insignificant beings and 

 small things to those which are great, I conclude that a Pure Intelli- 

 gence will rarely act by intervention, but always through law. 



Through that astronomical agency to which I have referred — the 

 action of light exerted during the period of the deposit of the coal — a 

 purification of the atmosphere was efiected to such an extent as grad- 

 ually to enable warm-blooded animals to exist, the temperature to 

 which they attain being directly dependent on the amount of oxygen 

 they take from the air. All animals, from the first period of their 

 coming into existence to the moment of death, are continually, by 

 their respiratory eflbrt, obtaining this gas, so essential to their very 

 existence, and as continually expelling the efiete and dead matters of 

 their systems, under the forms of other airs — carbonic acid, ammonia, 

 and the vapor of water. And thus the atmosphere is the source from 

 which our bodies come, and to which they return, continually during 

 life, and, with the exception of their earthy ingredients, totally after 

 death, and the gases that are found in it are at once the agents and 

 objects of the change. Had Priestley realized these things, could he 

 have induced Chemistry by her witchcraft to compel the gas he had 

 discovered to tell its own story, and how it determined his destiny, 

 his imaginative but theological mind would perhaps have recalled the 

 similarity of its own adventurous inquiry with that of the old Jewish 

 king who visited the sorceress at Endor. Awakened by the power of 

 her spell, there arose, from the enchanted circle over which she waved 

 her wand, the form of an old man whose face was shrouded in his 

 mantle. And he said, " Why hast thou disquieted me, to bring me 

 up ? To-morrow shalt thou and thy sons be with me." 



Some seek for pleasure in the mere gratification of animal appetites, 

 let us rather find it in the exercise of the intellect ; and, when spring 

 approaches, let us rejoice in the change, not so much because there is a 

 promise of food, though we should never forget that all these vegeta- 

 ble products, of which so many are destined to delight our tastes, were 

 mortal poisons while they were yet in the air, but chiefly because they 

 are indications that all that is necessary for us as thinking beings is ac- 

 complishing. I have told you that the continuance of the life of man 

 is indissolubly linked with the putting forth of the buds of trees. Let 

 the one fail, and the other will speedily stop, ^ay, more ; as all our 

 intellectual acts can only go on as a consequence of respiration, and 



