PRIESTLY 47 



gether, but if the nostrils were kept shut I was led to believe that it might be 

 breathed in safety. I found for example that when sparrows died in it in ten or 

 eleven secondsi, they would live in it three or four minutes when the nostrils 

 were shut by melted suit. And I convinced myself that the change produced on 

 wholesome air "by breathing it consisted chiefly, if not wholly, in the conversion 

 of part of it into fixed air. For I found, that by blowing through a pipe into 

 lime water, the lime was precipitated, and the alkali was rendered mild. ♦ * ♦ 

 In the same year I found that fixed air is the chief part of the elastic matter, 

 which is formed in liquids in the vinous fermentation. Van Helmont has indeed 

 said this. But it was at random that he said it was the same with the Grotto del 

 Cane in Italy (but he supposed the identity because both are deadly), for he had 

 examined neither of them chemically, nor did he know that it was the air dis- 

 engaged in the effervescence of alkaline substances with acids. I convinced 

 myself of the fact by going to a brew house with two phials, one filled with dis- 

 tilled water and the other with lime water. I emptied the first into a vat of 

 wort fermenting briskly, holding the mouth of the phial close to the surface of 

 the wort. I then poured some of the lime water into it, shut it with my finger, 

 and shook it. The lime water became turbid immediately." 



Black goes on to criticise Van Helmont's pronouncements as 

 mere chance statements. He, himself, verified all his conclusions by 

 repeated experiment. 



As Black re-discovered under the term "fixed air" that which 

 Van Helmont had recognized a century before, so Mayow's igneo- 

 aereal salt or spirit was re-discovered by Priestly and Lavoisier. 



Priestly and His Dephlogisticated Air: With the name of Joseph 

 Priestly, perhaps more than any other, is associated in the modern 

 mind the discovery of oxygen, though he did not make use of the 

 term. Of him Frederick Harrison has said: 



"If we choose one man as a type of the intellectual energy of the eighteenth 

 century we could hardly find a better than Joseph Priestly, though his was not 

 the greatest mind of the century. His versatility, eagerness, activity and hu- 

 manity; the immense range of his curiosity in all things physical and social; his 

 place in science, in theology, in' philosophy and in politics; his peculiar relation 

 to the Revolution, and the pathetic story of hisi unmerited sufferings, may make 

 him the hero of the eighteenth century." 



He was bom near Leeds, England, in 1733, and died in the United 

 States in 1804. His boyhood was uneventful. His family was de- 

 scribed as "simple, sober, honest. God-fearing folk, staunch Calvinists 

 and deeply religious." The son inherited these qualities and entered 

 the ministry as a Unitarian preacher, an act which was particularly 

 offensive to the orthodoxy of the time. Benjamin Franklin, to whom 

 Priestly is endebted for the incentive for scientific study, refers to 

 him in a letter as an "honest heretic." And continuing in Franklin's 

 charactersitic style, he says: 



"I do not call him honest by way of distinction, for I think all the heretics 

 I have known have been virtuous men. They have the virtue of fortitude, or 

 they would not venture to own their heresy; and they cannot afford to be dif- 

 fident in any of the other virtues, as that would give advantage to their many 

 enemies; and they have not like orthodox sinners, such a number of friends to 

 excuse or justify them. Do not, however, mistake me. It is not to my good 

 friend's heresy that I impute his honesty. On the contrary 'tis his honesty that 

 has brought upon him the character of heretic." 



