(2J9 ) 



N°. 83 III § 4 These Proc. Fehr. 1903). Sufficient precautions were 

 taken to prevent conduction of heat from outside to parts of the apparatus. 



§ 3. Variations of density found in the repetition of the experi- 

 ment of de Heen after correction of the difference in temperature 

 of the reservoirs. 



De Heen brings the temperature of the two reservoirs (see $ 2 

 beginning) from 28° to about 35° C, and opens the cock between 

 them 6 times four seconds during the heating ; then when the 

 temperature lias become constant at about 35°, he opens the 

 cock once more 6 times 4 seconds. Then he assumes that tempe- 

 rature and pressure are the same in the two reservoirs. 



When repeating the experiment (being very careful to prevent 

 drops from being scattered from one reservoir into the other) we 

 found confirmed by reading the thermo-elements (nickel-iron), what 

 was observed in Comm. N°. 68 viz. that every time when the cock 

 between is opened for adjustment of pressure, a difference of tempe- 

 rature arises between the two reservoirs, and that when closing the 

 cock at the end of the experiment a difference of temperature remains, 

 which must be taken into account. 



In order to find out in how far the equilibrium of temperature 

 and pressure has been reached, -we have in the first place made 

 three determinations, in which the cock was opened respectively 

 2, 4, and 6 seconds every time (probably our cock allowed compara- 

 tively less substance to pass than that of de Heen). The results have 

 been given in the following table : v denotes the upper; / the lower 

 reservoir, so qi is the density in the lower reservoir; the numbers of 

 times the cock was opened during the heating (distributed over 

 15 minutes) and then at constant temperature (distributed over half 

 an hour) have been separately given; q'i is o/ corrected for t — ti. 



SERIES I. 



