ON THE ABSOLUTi; KXI'ANSION OF MERCURY. 29 



then- docs not si-fin to In- any sufficient reason for changing the final value of the 

 boiling-point of sulphur on the scale of the constant-pressure air or nitrogen 

 thermometer from that given in the previous note and assumed for so many years, 

 nrmiely, t = 444'53 C. 



12. Explanation of the Tables of Expansion. 



The accompanying tables of the expansion of mercury from 30 C. to 309" C., 

 together with the table of differences on the opposite page, make it easy to calculate 

 the expansion from C. to any other temperature within the given limits. If one 

 of the limits be not C., the volume at each limit must be found, and the difference 

 taken. 



The following examples will make the use of the tables clear : 



(1) To find the expansion from C. to 221145 C.- 



Expansion from C. to 221 C 0'0407846 



Difference for 0'l C. at 220 C 190 



0'04 C. 220 C 76 



0'005 C. 220 C 10 



Expansion from C. to 221'145 C '0408 122 



The values found in this way from the tables will, in general, be correct to 1 in the 

 last figure, or 0'001 C., as given by formula (8). 



(2) To find the expansion from -10'450 C. to -1- IG'109 C.- 



Volumeat-10C ........... 0'9981957 



Difference for -0 '4 C. at-10C ..... 722 



-0'050C. -10 C ..... - _ 90 



Volume at -10 '450 C .......... 0*9981145 



Volume at + 16 C ........... 1 "0028922 



Difference for 0'l C. at 16 C. 



0'009C. 16 C ...... + 





Volume at +16-1090 



Volume at -10-4500 .......... ' 9981U5 



Expansion between limits ...... 



