THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



JUNE 1844. 



* 



LIX. Experiments on the Heat disengaged in Combinations. 

 By Thomas Graham, Esq., F.R.S., #c* 



Part II. Neutralization of various Acids by Hydrate of Potash. 



THE arrangements adopted for observing the heat evolved 

 on neutralizing acids by potash were similar to those de- 

 scribed in the former paper. The same platinum crucible, 

 weighing 1201*9 grains, and hollow cylinder of palladium, 

 weighing 207'6 grains, were employed as the containing ves- 

 sel and stirrer ; but the constant quantity of water employed 

 as a vehicle for the acid and alkali was increased from 1000 

 grains to 1544 grains, or 100 grammes, while the equivalent 

 quantities of the substances used were the same as before. 

 The solution of the saline body formed in an experiment was 

 consequently one-half more dilute, and the small but sensible 

 effect of further dilution of the solution in producing cold, ob- 

 servable in some of the former experiments, was thus entirely 

 avoided, while the increase of the mass of fluid reduced the 

 influence of external causes on its temperature. A mercu- 

 rial thermometer of greater delicacy was employed, of which 

 the bulb was a cylinder of 1*25 inch in length and 0*3 inch in 

 diameter; the scale was graduated into degrees Fahrenheit, 

 ranging from 40° to 70°, each degree being 0*42 inch in length 

 (0*74 inch for one degree centigrade), divided into tenths of a 

 degree, each of which could again be subdivided into fifths 

 by the eye, so that the observation was made to one-fiftieth 

 of a degree Fahrenheit. The eye was directed to the scale 

 through a straight cylindrical tube of small diameter, sup- 

 ported in a horizontal position. The mercury in the bulb of 

 the thermometer was equivalent in capacity for heat to 11*5 



* Communicated by the Chemical Society* having been read January 

 15, 1844. 

 Phil Mag. S. 3. Vol. 24. No. 161. June 1844. 2 D 



