INFLUENCE OF THIS FORCE. 219 



proving that the mere circumstance of elevation 

 is no obstacle to the force which impels the gas 

 upwards. 



The same diffusive force scatters gases abroad 

 laterally as well as in the perpendicular direc- 

 tion. A French chemist, M. F. Leblanc, insti- 

 tuted a series of experiments upon the amount 

 of carbonic acid present in confined air, and his 

 results show, in the most complete manner, that 

 by these ever-active agencies the air of our 

 chambers is renewed and preserved from an 

 excess of carbonic acid, and our habitations, 

 with all their comforts and warmth, are made, 

 as far as regards their amount of carbonic acid, 

 to enjoy a degree of purity of air not so very 

 far inferior to the open spaces in which they 

 may be placed, as might have been anticipated. 



We owe to diffusion more than this. The 

 balmy air which every now and then comes to 

 us, odorous with the simple perfume of the violet 

 or hedge-row, or with the peculiar fragrance of 

 the new-mown hay, would be deprived of all its 

 scented properties, and would be felt without 

 pleasure and inhaled without delight, were it not 

 for the power of diffusion. As, while we stand 

 thus discoursing on nature's chemistry, we drink 

 in the pure fragrance of such flowers as lie 

 scattered around, and perceive such freshness 

 and delightful property in the air, let us remem- 



