1.  All gases exert pressure on their surroundings.

     2.  The pressures exerted by individual gases in the same vessel are independent of each
          other.

     3.  Dalton's Law:  The partial pressure of a gas in a gas mixture is the pressure the
          gas would exert if it occupied the total volume of the mixture in the absence of the other
          components.

     4.  The partial pressures of all gases in a gas mixture can be summed to give the total pressure
          of the mixture.

          Example:  Ambient air contains 21% oxygen (O₂) and 78% nitrogen (N₂).

          If atmospheric pressure  =  760 mmHg, then

               Po₂  =  760  x  0.21  =  160 mmHg

               PN₂  =  760  x  0.78  =  593 mmHg

          The sum of the partial pressures of oxygen, nitrogen, carbon dioxide (CO₂), and all
               other gases in ambient air is 760 mmHg.

     5.  The number of gas molecules which dissolve in a liquid is proportional to the partial
          pressure of the gas.

     6.  Henry's Law:  The concentration of a gas dissolved in a liquid is proportional to its
          partial pressure.

     7.  The proportionality constant is the solubility of the gas in the liquid.

     8.  At equilibrium, the partial pressure of a gas in solution is equal to its partial pressure in
          the gas mixture.

          Example:  Solubility of oxygen in blood  =  0.003 ml O₂/100 ml blood/mmHg Po₂

          If Po₂  =  100 mmHg, then the concentration of oxygen dissolved in blood  =
              100  x  0.003  =  0.3 ml O₂/100 ml blood.