364 CARNEGIE INSTITUTION OF WASHINGTON. 



capacity of the system during the reaction, one could compute the 

 energy-change at each temperature, and therefore the amounts of heat 

 needed to cause the successive definite rises of temperature. Upon 

 introducing the small correction involved by the changing specific 

 heat of water, it was possible to subdivide the thermoelectric scale by 

 these successive steps, and the results indicated that the 18° point of 

 our standard thermometers was thermodynamically somewhat above 

 that half-way point between 16° and 20°. 



The exact amount of this deviation was not fully decided; more 

 experiments were needed. Accordingly, during this last winter, with 

 the help of Dr. Sekuro Tamaru, a somewhat similar method of sub- 

 dividing the thermometric scale was employed, this time taking the 

 energy from a galvanic cmTent passing through a known constant 

 resistance. The process, which involves experimentation precisely 

 like that in a common method of determining the varying specific heat 

 of water, enables us to determine the errors of our thermometers over 

 this range if we assume the relative specific heats of water between 16° 

 and 20° to be known. Many different trials were made, and all 

 except one (which was undoubtedly complicated by an accidental 

 error) agreed in giving essentially the same appreciation of the thermo- 

 metric error at 18° as that given by the previous thermochemical work 

 with Dr. Thorvaldson, although the deviation was not quite so great 

 as that shown before. The thermometric scale thus constituted seems 

 to be the best of any yet at our disposal, but it will be subject to yet 

 further scrutiny and analysis. Much depends upon the correct solu- 

 tion of this problem, because a large amount of thermochemical work 

 carried out by Dr. A. W. Rowe and others, with the help of these 

 grants, is waiting for codification and publication until the thermo- 

 metric observations, made carefully with the excellent thermometers, 

 can be reduced to the true thermodynamic scale. Next winter it is 

 proposed to verify the conclusions by reference to the best electrical- 

 resistance thermometers and thermoelectric couples obtainable. 



4. The Heat of Solution of Metals. 



This problem was undertaken in continuation of the work done by 

 Dr. Thorvaldson last year, with the new apparatus devised with his help. 

 The present investigator was Dr. Tamaru, who not only repeated Dr. 

 Thorvaldson's results with zinc, but also carried out similar determina- 

 tions with cadmium, as well as a number of determinations of the 

 specific heat of the solutions involved. The results with zinc agreed 

 very well with those of Dr. Thorvaldson, and there is therefore good 

 reason to believe (because the method gives identical results in differ- 

 ent hands) that the outcome for zinc is to be depended upon and that 

 for cadmium is also trustworthy. 



