We read a lot about xxx tons of CO2 or whatever, but I have trouble imaging the weight of a volume of a gas. I have read that water is about 800 times denser than air, so from that one could calculate the weight of a cubic meter of air, for example. But how about other gases? Is there a metric rule of thumb? Why do engineers measure the output of a gas by weight in the first place?
HARRY WYETH
