&8- Miss D. Marshall on the Heats of Vaporization 



that of the surrounding liquid, and may change a little with 

 the irregular escape of hubbies of vapour : such changes in 

 temperature would at once affect the resistance of a platinum 

 wire, but would be less operative in the case of platinum- 

 silver, which has but a small temperature- coefficient. It was 

 found, however, that the substitution of platinum-silver for 

 platinum makes no difference whatever ; provided that the 

 current is allowed to run for 10 or 15 minutes before the 

 beginning of the experiment, the points of balance are found 

 just as easily for one pair of vessels as for the other, and the 

 numerical results previously obtained were confirmed. 



§ 3. A number of experiments were made in order to see 

 whether the same results are obtained when different strengths 

 of current are used, i. e. when the D.P. across the terminals 

 is altered. The limits of alteration are not wide, because if 

 the current be made too weak or too strong mechanical diffi- 

 culties arise : but within these practical limits the conclusion 

 drawn is that alteration of current-strength produces no effect 

 This is shown in the accompanying table, where R = ap- 

 proximate total resistance in circuit, E.M.F. being about 

 85 volts. 



Table I. — Benzene and Alcohol. 



B. 



R. 



95 ohms. 



85 „ 



7 



Weights evaporated. 



Ratio — l 



*2 



Corrected Weights. 



Ratio h 



Alcohol. 



Benzene. 



Alcohol. 



Benzene. 



772-5 mm. 

 771-8 „ 

 772-5 „ 



7-829 



9-045 



10-525 



14093 

 16139 



18-669 



1-272 



1-285 

 1-293 



7-829 



9-045 



10-525 



17-930 

 20-739 

 24-139 



2-290 

 2-293 

 2-293 



§ 4. Table II. records the values of L obtained for nine 

 new liquids, each being compared with benzene. Data 

 regarding the source and purity of these liquids are given in 

 an Appendix. 



