202 LudeJcing and Starr— Specific Heat of Ammonia. 



Total water value of calorimeter, thermometer 



and water . . 151*76 cal. 



Water value of steel cylinder 8'34 cal. 



Temperature of air 2f>°*4 C. 



Temperature of steel cylinder.. .. 46°*51 C. 



Temperature of calorimeter after immersion, 26°*69 C. 

 Calorimeter before immersion 24°*44 C. 



Rise in temperature 2°*25 C. 



Thus 341*46 cal. were given off by the cylinder in cooling 

 19°*82 or 17*23 cal. for one degree. Of this 8*34 cal. are due 

 to the steel cylinder itself, leaving 8*89 cal. for 10*01 grams of 

 liquid ammonia or 0*888 per gram = specific heat. In a sec- 

 ond and third experiment the values 0*897 and 0*896 were 

 obtained. The determination of the specific heat of liquid 

 ammonia would be influenced, as stated, by the latent heat of 

 condensation of part of the small quantity of vapor present, 

 when the cylinder cools in the calorimeter. This would to a 

 degree be neutralized by the contraction of the liquid ammonia 

 itself in the cooling and the consequent formation of more 

 vapor space. 



It seemed desirable to ascertain the influence of these factors 

 collectively by experiment. For this purpose specific heat 

 determinations were made in a way somewhat different from 

 the ordinary. The steel cylinder was cooled in an iron shell 

 in melting ice, instead of being heated, and then introduced 

 into the warm calorimeter water. The mode of procedure 

 was in detail similar to that described above and we will there- 

 fore only give our results. In three experiments the values 

 0*878, 0*863, and 0*892 were obtained. They are a trifle lower 

 in their average than the results obtained by the ordinary 

 method. It is reasonable to assume that they are somewhat 

 low, while as stated the other results are presumably some- 

 what high and in order to arrive at the specific heat of this 

 substance nearest the true value from our experimental evi- 

 dence, we will take the average of our six values, viz : 



0*888 ) 0*878 ) 



0*897 [ 1st series. 0*863 [■ 2d series. 



0*896 ) 0*»92 ) 



and state it as being = 8857. 



We beg herewith to acknowledge our obligations to Chan- 

 cellor W. S. Chaplin and Prof. Wm. B. Potter for kindly 

 placing the laboratories under their charges at our disposal. 



Cove Mills, Stamford, Conn. 



