SULPHURIC ACID FOR WATER. 361 
EVAPORATING FORCE. 
~ Morn. Noon. Night. 
Inch of Mer, | Inch of Mer.| Inch of Mer. § 
0.13 0.13 0.14 
0.14 0.16 0.17 
0.15 0.15 0.15 
0.15 0.15 0.15 
0.15 0.15 0.15 
0.15 0.13 0.15 
On comparing the results of the several weigh- 
ings with this register of evaporating force, we 
observe that weight was found to be lost till and 
on the morning of the 5th, and that from the 
commencement of the experiment to that time 
the evaporating force had ranged from 0.13 of an 
inch of mercury to 0.17 of an inch. We also 
observe that on the morning of the 6th a slight 
regain of weight was found; and that from the 
morning of the 5th to that of the 6th the evapor- 
ating force had all the time been stationary at 
0.15 of an inch of mercury. Up to the night of 
the 4th the acid had become concentrated to such 
a degree as that it was capable of resisting an 
evaporating force of 0.16 or 0.17 of an inch of 
mercury ; and when the evaporating force hap- 
pened to be reduced on the 5th to 0.15 of an 
inch, the acid was so far capable of overcoming 
that force as to regain 0.2 of a grain, and to 
retain that on the 6th, and as long as the evapor- 
ating force remained as then. 
22 
