NOYES AND GOODWIN. — VISCOSITY OP MERCURY VAPOR. 233 



(See expression (2), page 229.) As the headiugs indicate, the first of 

 these two series of experiments was made with the smaller, and the sec- 

 ond with the larger capillary. It will be seen that in the second series 

 two sets of determinations are given for mercury vapor : the first of these 

 was made before and the second one after the experiments with carbon 

 dioxide and hydrogen, and their agreement shows that the capillary had 

 undergone no change by stoppage or otherwise during the course of the 

 experiments with it. 



SERIES I. 

 Small Capillary. 



Attention may be first called to the agreement of the values of the 

 ]a^<t column in the case of the ti'anspiration of the same substance under 

 different ditFerences of pressure, thus proving that the effect of pressure 

 is in close accordance with that required by the formula, and conse- 

 quently that the capillaries are of sufficient length and small enough 

 bore to give the true values of the viscosity coefficients. 



Of the two series of experiments the first one made with the smaller 

 capillary is to be regarded as the less reliable by reason of the fact that, 

 owing to an accident to the capillary, check experiments with mercury 



