56 



THE ROYAL SOCIETY OF CANADA 



Date. 



May 13 

 « 16 

 " 26 



Temp, of 



steam. 



99-986°C. 



99-79°C. 



99-975°. 



Overflow 

 grams. 



Weight at 100°C. 

 grams. 



27-1248 

 27-0869 

 27-1495 



1500-04 

 1500-04 

 1500-04 



Coefficient 



neglecting the 



quartz. 



•00018081 

 •00018100 

 •00018100 



The mean of these gives for the mean coefficient between 0° and 

 100°C. neglecting the expansion of the quartz — 

 •00018094 

 Correcting for the quartz by using the value assumed above be- 

 tween 0° and 100° 



a = -00018241. 



Experiments at the Lower Temperatures. 



The dilatometer was suspended in the thermostat by the wire 

 holder. The stem, as before, was kept with the mouth dipping in 

 mercury held in the overflow vessel. The thermostat was then cooled 

 and held at the desired temperature for at least an hour. For the low- 

 est point no readings could be taken below -38°C. owing to the 

 freezing of the mercury which was observed to take place. We, 

 therefore, did not include any measurements which went below 

 -37-5°C. 



After obtaining the desired temperature the overflow vessel 

 was replaced by one containing a known mass of mercury. The 

 dilatometer was then lifted out of the thermostat and all methylated 

 spirits wiped from the surface. It was then placed in the ice bath 

 and left for at least an hour. The difference in the weight of the mass 

 of mercury contained in the overflow vessel was obtained, which gave 

 us a measure of the expansion without danger of sucking back air 

 into the dilatometer in case the removal of the spirits should cause 

 the temperature of the dilatometer to exceed 0°C. before the final 

 reading was obtained. 



