RICHARDS AND ROWE. — SPECIFIC HEATS OF LIQUIDS. 189 



the water equivalent of the rubber to 2.02. The thermometer had a 

 bulb occupying 3.90 cubic centimeters. Taking its heat capacity per 

 cubic centimeter according to Ostwald-Luther's well known experience, 

 this corresponds to a water equivalent of 1.83. The immersed stem 

 above the bulb was estimated to have a heat capacity of 0.65 on the 

 same basis, by careful weighing of bits of glass tube of the same 

 diameter and thickness. The sum of all these water equivalents was, 

 as has already been stated, 12.24. About 114.8 grams of dilute 

 sulphiu'ic acid (reqviiring 21.37 grams of the concentrated caustic 

 soda) were used for neutralization. The specific heats of these two 

 solutions w^ere taken respectively as 0.950^ and 0.8345.^ The uni- 

 formly employed excess of caustic soda (about 3 percent) above the 

 amount needed to neutralize exactly the sulphuric acid could l^e neg- 

 lected because its heating effect was enough to raise it through the 

 same range of temperature as the main experiment in the way already 

 explained. Hence the water equivalent of the sulphuric acid was 109.1 

 and of the caustic alkali 17.83. It will readily be seen that the specific 

 heat of neither sulphuric acid nor caustic soda needed to be known 

 with very great accuracy because they were essentially constant in 

 all the experiments. A slight error therefore would have a wholly 

 negligible effect on the results, which are relative in their character. 

 For example an error of 2 percent in the value assumed for the spe- 

 cific heat of the acid could only affect the final results by a few thou- 

 sandths of one percent, and there is no likelihood that the assumed 

 specific heat was anything like so much as even one percent in error. 



Data of a Specimen Experiment upon pure Water. Ser. IA, 



No. 1. 

 Temperature Data. 

 Initial Thermometer reading = 16.524° 

 Total Calibration Correction = — 0.033° 

 Initial Temperature (corrected) ( T'l) = 16.491° 



Final Thermometer reading = 20 . 752° 

 Total Calibration correction = — 0.038° 

 Final Temperature (corrected) (^2) = 20.714° 



Temperature Interval {T2-T1) = 4.223° 



Stem Exposure Correction = + 0.001 



7^2-^1 corrected 4.224° 



SMarignac, Arch. sci. nat., 2, 39, 217 (1870); Cattaneo, Cim., 3, 26, 50 

 (1889). Thomsen, Ther. Untersuch. 



9 Determined by the Authors. The experimental data will be given in 

 another paper. 



