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that it was fenfibly diminished in weight by the 

 operation. 



Air thus diminished by the fumes of burning char- 

 coal not only extinguifhes flame, but is in the higheft 

 degree noxious to animals ; it makes no efFervefcence 

 with nitrous air, and is incapable of being diminifhed 

 any farther by the fumes of more charcoal, by a 

 mixture of iron filings and brimftone, or by any other 

 caufe of the diminution of air that I am acquainted 

 with. 



This obfervation, which refpe&s all other kinds 



of diminifhed air, proves that Dr. Hales was mif« 



taken in his notion of the abforption of air in thofe 



circumftances in which he obferved it. For he fup- 



pofed that the remainder was, in all cafes, of the 



fame nature with that which had been abforbed, and 



that the operation of the fame caufe would not have 



failed to produce a farther diminution ; whereas all my 



obfervations not only mew that air, which has once 



been fully diminifhed by any caufe whatever, is not only 



incapable of any farther diminution, either from the 



fame or from any other caufe, but that it has likewife 



acquired new properties, mofl remarkably different 



from thofe which it had before, and that they are, 



in a great meafure, the fame in all the cafes. Thefe 



circumftances give reafon to fufpecl, that the caufe 



of diminution is, in reality, the fame in all the cafes. 



What this caufe is, may, perhaps, appear in the 



next courfe of obfervations. 



G g % VIII. 



