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Probable discovery thereof, by accident, in some 



Sidonian travellers . . 131 



28. Of the Bologna bottle; with curious experiments 



thereon . . . 132 



29. Of the glass-drop . . 133 

 Of the invention of gunpowder . 334 



30. Ot the nature and the properties of air . ib. 

 The weight or gravity of air . 136 

 f he elasticity of air , . 138 

 Experiments on air . . . 141 

 Of the air pump , . , 142 

 Farther experiments on air ,143 



31. Air is in all our fluids . i 144 



32. Air is the cementing^ and dissolving principle ]46" 



33. Air increases the weight of oil of vitriol . 149 



34. Air is capable of immense expansion . ib. 



35. Difference between fixed and common air r iso- 



CHAP. HI.. 



Of Meteors. 



J. Of vapours, mists, and clouds , 15* 



2. Of dew and rain . , 153 



Mr. Kersbaw's observations on dew I 3,54 



The various causes of rain - . . ib. 



A kind of bloody rain * . 155 



