Dalton's Law is named for John Dalton, who stated the law in
1801. The law states that the pressure exerted by a mixture of
gases is equal to the sum of the pressures which would be
exerted by the gases individually. P = p(1) + p(2) + p(3) ... +
p(n) Where P is the total pressure exerted by the sum of
pressures p. Dalton's discovery was all gases tend to compress
similarly. If you have a mixture of nitrogen and oxygen and you
add 100lbs of pressure both the nitrogen and oxygen will
compress equally. In other words, mixed gases will stay in the
same proportions under pressure - you will not find some gasses
compressing more than others. For instance, imagine squeezing a
cloth bag equally full of marbles and popcorn. You know that the
popcorn will compress more than the marbles and with sufficient
pressure the proportion of marbles and popcorn in the bag (by
volume) will change. Dalton's law assures us that among gases it
will not happen. To a scuba diver this assures us that our
bodies absorb gases in the same