epara

re up through the orifice in the shelf of a p.t. (pneumatic trough), having water at least l cm. above the shelf. Heat another wire, touch it to the P, and quickly invert an empty receiver over the P, having the mouth under water, so as to admit no a

easuring the water with a graduate; then fill it with water and measure that; compute the percentage which the former is of the latter. What proportion of the air, then, is O? What w

t O. Experiment 19 will prove this conclusiv

roper

appeared, slide the plate along, and insert

Since it does not unite with C, S, or P, is it an active or a passive element? Compare it wit

s, physical and chemical, of

will even go through a carbon crucible to unite with it. It is not combined with O in the air; but the two form a mixture (page 86), of which N mak

rom compounds in earth, water, and air. By reason of its inertness N is very easily set free from its compounds. For this reason it is a constituent of most explosives, a

as the nitrates; but the great source