512 RUDBERG ON THE EXPANSION OF DRY AIR. 



The mean of the twenty-four results gives the difference be- 

 tween the true expansion of mercury and the expansion in vo- 

 lume of potash glass, 100 M - 100 G = 0015733. Hence 

 the true expansion in volume of the potash glass of Reymyra 

 from 0° to 100°, 



100 G = 0-002285. 



In the following table of the results of nine observations, p 

 and p — q are expressed in grammes, and h, k, I in centimetres. 



The value of 100 A. in the sixth line is too small, in conse- 

 quence of the loss of a globule of mercury in one part of the 

 experiment. The mean of the preceding values of 100 A. is 

 0-3646. 



Two other experiments w^ere made with cylinders of glass. It 

 was found impossible to boil the mercury contained in them, on 

 account of the smallness of the bore of the tubes which formed 

 their necks. The results are therefore considered less accu- 

 rate. 



p. p-q. h. k. I. T. 100 A. 



1158-902 . 946-516 . 76773 . 76-789 . 7-80 . 100-28 . 0-3646 



1196-992 . 991-695 . 76-313 . 75470 . 792 . 10012 . 0-3662 



Mean 0-3654 



Two other observations were made without previously drying 

 the air with chloride of calcium, in which, however, an exami- 

 nation with a microscope showed that there were no visible drops 

 of water in the globe. These experiments were made merely 



