1 66 On Steam and Brines 



117 grms. of this salt in the tube to begin with. Two minutes 

 were sufficient for heating up to 100 C. In two experiments 

 the amounts of steam condensed were 9-8 and 9*6 respectively, 

 giving a mean of 97 grms. In a similar experiment, where 

 the passage of steam was not stopped until the salt was all 

 dissolved, which took 16^ minutes, the steam condensed was 

 31-5 grms. Deducting 9-7 grms. we have 2r8 grms. condensed 

 in 14^ minutes, or 1*5 grms. per minute. The rate of con- 

 densation is naturally higher, because salt is being dissolved. 

 With the apparatus empty at the start, 9*0 grms. steam are 

 condensed in the first two minutes; with a charge of 117 

 grms. chloride of sodium, 97 grms. of steam are required ; 

 the excess, or 07 grm., may be taken as the steam condensed 

 by the NaCl in the two minutes, and as constant for the same 

 amount of NaCl in other apparatus. 



The boiling tube used in all the experiments up to 26th 

 October 1897 weighed, with thermometer, I57'3 grms. This 

 would require 5'5 grms. of steam in order to raise it to 100 C., 

 and the heating would be complete in one minute instead of 

 in one and a half minutes as with the apparatus weighing 

 239 grms. Allowing ro grm. for the amount of steam con- 

 densed in the next minute, we should have, after two minutes, 

 6'5 grms. steam condensed. Where ^ NaCl was used, we 

 should have to add 07, and the amount thus condensed at 

 the end of the first two minutes would be 7'2 grms. The 

 rate of condensation per minute, after the first two minutes, 

 would be | i '3 5 or 0*9 grm., and adding o - i5 for the 

 chloride of sodium, we have 1*05 grms. per minute, taking 

 30*4 grms. as the amount of steam required to be condensed 

 for i NaCl. 



Localities where Experiments were made. The lowest 

 station, and the one representing the sea-level, was my 

 laboratory in Edinburgh : its elevation is about 85 metres, 

 or 279 feet, above the sea. Although a large number 

 of experiments in this field had been made in the course 

 of previous years, those utilised for this paper were all made 

 after my return from Switzerland, with the same apparatus 

 and the same thermometers that were used there, and 



