224 Determination of Boiling and Freezing Points. [June 19, 



(t?.) The presence of currents due to thermal effects. 



(e.) Superheating during distillation, and radiation from the source 

 of heat to the thermometer. 



(/.) The changes in boiling points due to changes in the baro- 

 meter. 



(#.) Oxidation of the metals when fluid. 



For an account of the manner in which these difficulties were over- 

 come, and of the further precautions taken to secure accuracy, refer- 

 ence must be made to the paper. 



The boiling points of the following substances were determined : 

 Aniline, methyl salicylate, triphenyl methane, and mercury ; and the 

 freezing points of tin, bismuth, cadmium, lead, and zinc. Every 

 endeavour was made to secure pure specimens of these bodies. 



Full particulars of the individual experiments are given in the 

 tables attached to the paper, and the results are summarised in the 

 accompanying tables. 



In Table I, I give certain boiling points as determined by means of 

 thermometers A, B, C, D, and E*. I have thought it unnecessary to 

 give details in Table I, since the forms of thermometers used therein 

 were ultimately discarded in favour of the form adopted in E, F, and 

 G. The mean results, however, are in close agreement with those 

 given in Table II (see pp. 222228). 



Table I. 



In Table II, I give the results obtained from thermometers E, F, 

 and G, together with the extreme departure of any single determina- 

 tion from the mean. 



In case the values of the fixed points assumed when graduating 

 these thermometers are hereafter found to be inaccurate, sufficient 

 data are given in the tables attached to the paper for the correction 

 of the temperatures given in column VI. 



The results given bear out the following conclusions : 



I. That although the curves of platinum temperature obtained 



The apparatus used for melting these metals, and for stirring them when 

 cooling, was kindly placed at my disposal by Messrs. Neville and Heycock, and is 

 described by them in their paper on the Melting Point of Alloys (' Journal of the 

 Chemical Society,' May, 1890). 



