EDITOR'S TABLE. 



3 6 9 



a clergyman and a chemist, and in 1768 

 he went to Leeds, and was settled as 

 pastor over a large congregation. He 

 happened to reside near a brewery, and 

 " accidentally observed that the beer, 

 during its fermentation in the vats, 

 gave forth a remarkable aerial sub- 

 stance. The flame of a lighted stick 

 immersed in it was at once extin- 

 guished, and the smoke floating on the 

 top of the stratum showed that it was 

 very heavy, a result which was perfect- 

 ly confirmed by the observation that, 

 invisible and intangible as it was, it 

 could be poured from vessel to vessel 

 like water ; and in the vats, in which it 

 originally occurred, it would overflow 

 their edges, and descend to the floor, 

 along which it would run like a stream, 

 its course being readily tracked by the 

 expedient of putting a lighted stick into 

 it, and observing the extinction of the 

 flame. Moreover, he found that it 

 would dissolve in water, for, if dishes 

 of that liquid were placed where it 

 had access, an agreeably acidulous and 

 sparkling fluid, soda-water, was formed ; 

 and, that the agent which brought all 

 these results about possessed a physio- 

 logical potency, was proved by the fatal 

 fact, too often known in such manu- 

 factories, that, if by accident it was 

 breathed, death at once took place." 



This substance was then called 

 "fixed air," and is familiarly known as 

 carbonic-acid gas. It is now exactly a 

 hundred years since Priestley published 

 a pamphlet " On impregnating "Water 

 with Fixed Air," and a year later he 

 received the Copley medal from the 

 Royal Society for his " Observations on 

 the Different Kinds of Air." In the year 

 1774, he made the splendid discovery 

 of oxygen, and, in allusion to its power 

 as the sustainer of life, he applied to it 

 the epithet " vital air." When it is re- 

 membered that this wonderful sub- 

 stance is the active element of the at- 

 mosphere, and essential to the existence 

 and activity of the entire living world; 

 that it enters largely into the composi- 

 24 



tion of all the natural objects around 

 us, forming three-fourths the weight 

 of all living things, half the weight of 

 the rocky strata, and eight-ninths of 

 the oceans; and, moreover, that it is an 

 element of great chemical energy, and 

 is involved in nearly every transforma- 

 tion of matter in the laboratory of Na- 

 ture, and in the processes of the arts, 

 we shall be prepared to comprehend 

 the significance of its discovery. It 

 has given us a new chemistry and a 

 new physiology, and it probably carries 

 the mind of man deeper into the order 

 of Nature than any other single scien- 

 tific revelation ever made. 



But the great discoverer had his 

 troubles. He carried his independence 

 and power of thought into theology 

 and politics, and his life of course be- 

 came a turbulent battle with sects and 

 parties. In relation to this part of 

 Priestley's career, Dr. J. W. Draper has 

 well remarked : " We must not impute 

 it to mental weakness, but rather to a 

 pursuit of the truth, that in succession 

 he passed through many phases of re- 

 ligious belief, and four different sects, 

 the Presbyterian, Arminian, Arian, and 

 Unitarian, received him as a votary. 

 This is not the occasion nor the place 

 to explain the causes which led him to 

 this course. It is only for us to judge 

 of so great a man with charity. But, 

 imbued as he was with a deep religious 

 sentiment, and feeling that even the 

 most exalted objects of this life are not 

 to be compared with the importance 

 of another world, he regarded his phil- 

 osophical pursuits as a very secondary 

 affair, and gave much of his time and 

 talent to controversial theology. He 

 seems to have come to the conclusion 

 that it was incumbent on him to make 

 a religious war. As his biographer 

 says, ' Atheists, Deists, Jews, Arians, 

 Quakers, Methodists, Calvinists, Catho- 

 lics, Episcopalians, had alike to combat 

 him.' In more than a hundred vol- 

 umes which he printed, each of these 

 found an adversary of such force and 



