no 



Chemical and Physical Notes 



height of a column of mercury at o C. at the sea-level, and in 

 latitude 45. In the fourth column the temperature of saturated 

 steam or the boiling-point of water under these true pressures 

 is given. It will be seen that, other things being the same, the 

 boiling-point of water at the sea-level is O'I47 C. higher at the 

 pole than it is at the equator. This figure is based on the 

 assumption that the mass of the earth is homogeneous, or 

 if heterogeneous, that it is symmetrically heterogeneous with 

 reference to its centre. It is also assumed throughout the 

 whole of this argument, that there are no fluctuations in the 

 atmosphere itself, and that the quantity of air in a column 

 having unit area of base, at the sea-level, is everywhere the 

 same. 



TABLE XVIII. Giving the True Atmospheric Pressure and 

 the Boiling-Point of Water Corresponding to a Barometric 

 Height of 73 5 '5 Millimetres at o C. and at the Sea- Level 

 in Different Latitudes. 



In the tabular example it is imagined that we carry 

 a standard barometer from the equator to the pole, and that 

 we read it at the sea-level in certain latitudes, the barometer 

 being entirely and exactly at the temperature of melting ice ; 



