272 Scientific Intelligence. 
the well and the basin; so that the greatest difference of temperature 
at the two extreme levels corresponds precisely to the moment of the 
eruptions. 
We can now ascertain what would be the boiling point of water 
submitted to a pressure equal to that of the atmosphere, were by 
the liquid column, the height and mean temperature of w we have 
determined in our five experiments. For this purpose, we must first 
express the pressure of this liquid column in millimetres of mercury 
at 0° density of the water of the Geysir, found at from 1-0010 
- 10° centigrade ; the curve which represents the results obtained by 
M. Isidore Pierre for the dilatation of distilled water, and which | ad- 
mit as being applicable to the water of the Geysir, extending it up to 
113° ; lastly, the density of the mercury at 0°, compared to that of 
distilled water at 4°, and found at 13°596 by M. eghaute enables us 
to make this reduction. We thus find that the heights of the columns 
of water in our different experiments correspond, in millimetres of 
mercury at 0°, to the following numbers :— 
Third and fourth aii 1-645 
Fifih experimen 1593 
First ex eriihent, 4 ‘ 1:587 
Second experiment, . ; 1°654 
From the equations 
log e=a-— be*, x—t— 100°, 
and from the data 
log e=1-9977641, log d—0-4692291, a=5'8267990, 
laid down by M. Regnault, in which e represents the tension of steam 
at saturation, expressed in millimetres of mercury, and x the tempera- 
ture to which that pressure corresponds, we can derive the value of # 
and of ¢; and this last quantity ~e py represent the boiling 
point of water submitted to the pres 
0°760-+-1™-645, 0 760-+-1™-593, 
0°760-+-10-587, 0-760-+ 1-654, 
The corresponding values of ¢ are as follow :— 
Third and fourth experiment, i. Slo 
Maximum temperature at the bottom, 127 
eee EUG ; i 9°-151 
Fifth experimen f ; t—135°-398 
Minimum sampetuie at the bottom, 122°'5 
Difference, : ; peo 7 
First experiment, : ; ; #—=135°'31 
Temperature at the bottom, ; : 122°°5 
Difference, . 2 ; . 12°81 
Second experiment, ; ; ; t= 136°:28 
Temperature at the bottom, gre, i 123°°60 
Difference, : : : ‘ 12°-68 
