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GKAJLUl LUSK 



of a glass apparatus which he had devised. This upper chamber was in 

 communication with a glass cylinder. The glass cylinder he filled with 

 "fire air" and immersed its lower end in lirne water. The volume of the 

 air within the receptacle diminished day by day and the lime water whicli 

 absorbed the carbonic acid rose in the tube. After eight days the bees 

 were both dead and the lime water almost completely filled the space. 



It is evident that Scheele had intro- 

 duced bees into pure or nearly pure oxygen 

 gas and that the carbon dioxid whicli they 

 produced had been completely absorbed by 

 the lime water. 



Scheele made no direct comment upon 

 this truly beautiful experiment but in the 

 general criticism of several experiments 

 one may read the following hazy general- 

 ization : 



Why do not the blood and lungs change 

 "fire air" into "acid air"? I take the liberty 

 to express my opinion concerning this, for 

 what would such exacting experiments profit 

 unless through them I had the hope to more 

 nearly approach my ultimate aim, the truth. 

 Phlogiston, which combines with most sub- 

 stances causing them to become more fluid, 



Fig. 3. Scheele's apparatus 

 showing bees in the upper chamber 

 01 a glass apparatus filled with 

 oxygen. 



more mobile aud more elastic, must have the same influence, upon the blood. 

 The blood corpuscles must absorb it from the air through delicate openings in 

 the lungs. Through this combination they are expanded and in consequence 

 become more fluid. In some part of the circulation they must give off this 

 absorbed phlogiston and consequently be able to again absorb this fine principle 

 when they next' reach the lungs. Whither the phlogiston goes during the circu- 

 lation I will leave to others to find out. The affinity of blood for phlogiston 

 cannot be as great as in the instance of plants and insects which take it from 

 the air and aferr-ther'Blood can wet-con vert it into "acid air," but it is changed 

 into a kind of air which is midway between "fire air" and "acid air"; it is 

 "spoiled air." For it does not unite w r ith lime water or water as does "fire air," 

 though it extinguishes fire as does "acid air." 



Scheele's "spoiled air" was nitrogen. The poor struggling apothecary 

 who had made so many careful and accurate experiments and who was 

 one of the greatest chemists of his time, was unable to interpret his results 

 without adherence to the dominant fetish of phlogiston. 



We have here the picture of two earnest men, Priestley and Scheele, 

 both absorbingly interested in chemistry, both contributing important 

 knowledge and ranking among the greatest scientists of their day, and 

 yet neither had the philosophical acumen to understand the meaning- oT 

 his experiments. Priestley was a Dissenting clergyman, earning his living 

 by preaching, but in his old age his house was burned by Loyalists and he 



