OP ARTS AND SCIENCES. 121 



Boscha has attempted to correct Regnault's results so as to reduce 

 them to the air thermometer ; but Regnault, in Cumptes Rendus, has 

 not accepted the correction, as the results were already reduced to the 

 air thermometer. 



Ilirn (Comptes Rendus, lxx. 592, 831) has given the results of 

 some experiments on the specific heat of water at low temperatures, 

 which give the absurd result that the specific heat of water increases 

 about six or seven per cent between zero and 13°! The method of 

 experiment was to immerse the bulb of a water thermometer in the 

 water of the calorimeter, until the water had contracted just so much, 

 when it was withdrawn. The idea of thus giving equal quanti- 

 ties of heat to the water was excellent, but could not be carried 

 into execution without a great amount of error. Indeed, experi- 

 ments so full of error only confuse the physicist, and are worse than 

 useless. 



The experiments of Jamin and Amaury, by the heating of water by 

 electricity, were better in principle, and, if carried out with care, 

 would doubtless give good results. But no particular care seems to 

 have been taken to determine the variation of the resistance of the 

 wire with accuracy, and the measurement of the temperature is 

 passed over as if it were a very simple, instead of an immensely diffi- 

 cult matter. Their results are thus to be rejected ; and, indeed, 

 Regnault does not accept them, but believes there is very little change 

 between 5° and 25°. 



In Poggendorff's Annalen for 1870 a paper by Pfaundler and Plat- 

 ter appeared, giving the results of experiments around 4° C, and 

 deducing the remarkable result that water from to 10° C. varied as 

 much as twenty per cent, in specific heat, and in a very irregular man- 

 ner, — first decreasing, then increasing, and again decreasing. But 

 soon after another paper appeared, showing that the results of the 

 previous experiments were entirely erroneous. 



The new experiments, which extended up to 13° C, seemed to give 

 an increase of specific heat up to about 6°, after which there was 

 apparently a decrease. It is to be noted that Geissler's thermometers 

 were used, which I have found to dejiart more than any other from 

 the air thermometer. 



But as the range of temperature is very small, the reduction to the 

 air thermometer will not affect the results very much, though it will 

 somewhat decrease the apparent change of specific heat. 



In the Journal de Physique for November, 1878, there is a notice of 

 some experiments of M. von Munchausen on the specific heat of 



