[*] The proportion of oxygen in the atmosphere varies from 21 to 22 per cent.
[CONVERSATION VII.]
ON HYDROGEN.
CAROLINE.
The next simple bodies we come to are CHLORINE and IODINE. Pray what kinds of substances are these; are they also invisible?
MRS. B.
No; for chlorine, in the state of gas, has a distinct greenish colour, and is therefore visible; and iodine, in the same state, has a beautiful claret-red colour. The knowledge of these two bodies, however, and the explanation of their properties, imply various considerations, which you would not yet be able to understand; we shall therefore defer their examination to some future conversation, and we shall pass on to the next simple substance, Hydrogen, which we cannot, any more than oxygen, obtain in a visible or palpable form. We are acquainted with it only in its gaseous state, as we are with oxygen and nitrogen.
CAROLINE.
But in its gaseous state it cannot be called a simple substance, since it is combined with heat and electricity?
MRS. B.