on the Passage of Air through Capillary Tubes. 437 



From this Table it is seen that, within the limits of experi- 

 mental error, the time taken for the passage of a given bulk 

 of air through the entire tube is equal to the sum of the times 

 taken for the passage of the same amount of air through each 

 of its parts. 



A similar experiment with a tube divided into a greater 

 number of parts was then made. The original tube was about 

 600 millims. long. 



(a) * = 85" 



(b) *=83" Mean 84". 



The tube was then divided without loss into 21 parts; these 

 were connected by caoutchouc and covered with paraffin. 



(a) £=86" 



{b) * = 85" Mean 85"'5. 



These experiments show that the terminations of the tubes 

 exert no special influence on the passage of the current. 



A conical or trumpet-shaped tube was then examined, the 

 arrangement being according to fig. 2. The following were 

 the results. 



Fiof. 2. 



Wide end towards greatest pressure. 



(a) £ = 183" 



(b) * = 184" Mean 183"-5. 



Narrow end towards greatest pressure. 



*=184". 



This shows that the rate is the same both ways. 



The foregoing experiments having shown that the effect of 

 temperature on the rate of a current was to be looked for in 

 its influence on fluid-friction, the next thing was to determine 

 the relation between temperature and time, other things being 

 the same. For this purpose a capillary tube, through which a 

 current was passing at a constant pressure, was subjected 

 down its entire length to various temperatures — care being- 

 taken that the air should arrive at the entrance of the capillary 

 tube at the temperature of the tube itself, so that the current 

 might be of the same temperature throughout the entire length 

 of the capillary tube. The times of passing of a given quan- 

 tity of air for different temperatures were noted ; and some of 

 the results are subjoined. 



