for Measuring the Expansiom of Solids^ Sfc. 275 



ware being nearly the least which has fallen under my obser- 

 vation, I repeated with it the experiment of the dilatation of six 

 of the former list of metals to the boiling point of water ; as 

 the accuracy of these observations is a point which it is of the 

 greatest importance to establish. 



The subjoined Table contains the results. 

 Table VIII. 



Platinum... 0°22' 



Iron 39 



Copper 54< 



Brass 59 



Gold 41 



Silver 58 



•00319 from 60° to 212° 

 •00566 



•00785 



•00857 



•00595 



•0084-3 



The differences of the observed expansions and the real are 



also subjoined and ranged by the side of those obtained by 



the first series of observations. 



Table IX. 



Expansion of the Metal Bars. 



Platinum absolute -00478 

 apparent -00319 



=-00159 00000 



Iron absolute -00640 



apparent -00566 



=-00074 —00085 



Copper ...absolute -00930 



apparent -00785 



Expansion of Black-lead. 

 Second Series. First Series. 



Differ, from Differ, from 



Mean. Mean. 



-00202 —00032 



Brass absolute -01045 



apparent -00857 



Gold absolute -00794 



apparent -00595 



=-00145 —00014 

 =•00188 +-00029 

 =•00199 +-00040 



Silver absolute -01034 



apparent 00843 



=00191 + -00032 



•00132 —00102 



•00247 + -00013 



-00246 +00012 



•00242 +-00008 



•00220 —00014 



Mean ^00159 00234 



The agreement of this second series with each other is quite 

 as close as that of the first ; and it is worthy of remark, that 

 the greatest variation from the mean is in both cases with the 

 iron in tleficiency, and nearly to the same amount of one half. 

 It is not unlikely, therefore, that there may be some error in 

 estimating the absolute dilatation of this metal, which is pro- 

 bably something greater than we iiave assumed. 



If we estimate the expansion for these 1 50° to the boiling 

 point of water from the result obtained by the boiling of mer- 

 cury, we shall have the following proportion : — 

 596° : -OOViO : : 150^ : '00110 



2 N 2 which 



