Conduction of Heat in Liquids. 



43 



From the values of U a very close approximation to X may be 

 obtained by Maclaurin's theorem, which gives X = 22 '79. This is a 

 much closer degree of approximation than is at all necessary, con- 

 sidering the possible size of the experimental errors. 



Since x — depth of wire = 2*61 cm., 



we get finally, the units being centimetre and minute, 



_ 6-8121 

 " ~ "9H6" 



= 0-0747. 



This corresponds to a temperature of about 18° C. 



The law of cooling of the dish on sulphuric acid solutions so nearly 

 resembled that on water, that it will be sufficient to take the results 

 given in Table I for a solution of density 1*2, and combine them with 

 the corresponding results for water in a ratio proportionate to the 

 strength of the intermediate solution. We thus obtain as propor- 

 tional to the heat given to the liquid in the first three half-minutes 

 the following values : — ■ 



First half- Second half- Third half- 



Density of solution. minute. minute. minute. 



1-054 601 396 243 



1 11 596 404 245 



1-14 593 411 247 



1-18 589 418 249 



Employing U and X in the same sense as for water, it will be 

 found, precisely as in the previous case, that the following results are 

 true for the various solutions. The last column gives the temperature 

 to which the conductivity belongs. 



Table III. 



Density 

 solution. 



X. 



U. 



Mean 

 value of 

 U. 



Tc. 



Temperature, 

 centigrade. 



1-054 



22-0 

 22 1 

 22 2 



-10" 3 x 12-4 

 + 10- 3 x 0-64 

 + 10~ 3 xl3-58 



22 095 



0-0759 



o 



20 \ 



1-10 



21 -4 

 216 



-10- 3 x 2 

 + lO" 3 x 28 -4 



21413 



0-0767 



20i 



114 



21 -4 

 21 -6 



-10- 3 x 1 

 + lO" 3 x 29 -6 



21-407 



0-0765 



19* 



1-18 



20-6 

 20-8 



-10" 3 xl7 

 + 10-» x 16 



20-703 



-0778 



21 



