246 Mr GRAHAM on the Law of 



rine. We may therefore presume that the diffusion of chlorine 

 is not incompatible with the law. 



4. Sulphurous Acid Gas. Over mercury. To diffusion-tube 

 with 7 measures air, 66 dry sulphurous acid gas were added, 

 which were allowed to diffuse into dry air. An expansion oc- 

 curred of 



5 measures in 9 minutes, 



13 23 



30 85 



31 108 



at which last expansion it remained steady. 



Assuming the specific gravity of sulphurous gas at 2.222, its 

 square-root is 1.4907, of which the reciprocal is 0.6708. 



67.08 sulphurous gas should be replaced by 100 air. 

 We have 66 sulphurous gas, and expansion 31, or, 

 66 sulphurous acid are replaced by 97.00 air, by experiment ; 



66 98.39 air, by theory. 



The diffusion-volume of sulphurous acid gas is, 

 0.68 by experiment, 

 0.67 by theory. 



5. Protoxide of Nitrogen. In an experiment with this gas, 

 dry, over mercury, allowing for a quantity of nitrogen which it 

 contained, 51 measures were replaced in ninety minutes, by 62 

 dry air. Taking the specific gravity of this gas at 1.2577, its 

 root is 1.2360, of which the reciprocal is 0.8091. 



Diffusion-volume 0.82 by experiment, 

 0.81 by theory. 



6. Cyanogen. Also over mercury. First deprived of hydro- 

 cyanic acid by peroxide of mercury, and dried, an expansion al- 

 ways resulted from diffusion, but it never amounted to the theo- 

 retical quantity. Taking 1.8105 as the specific gravity of cyano- 



