and water of crystallization?

9. If steam is heated to 2000 deg. and again cooled, has any chemical change
taken place in the steam?

10. Why is cold water passed into C instead of D (Fig. 24)?

11. Mention at least two advantages that a metal condenser has over a
glass condenser.

12. Draw a diagram of the apparatus used in your laboratory for
supplying distilled water.

13. 20 cc. of hydrogen and 7 cc. of oxygen are placed in a eudiometer
and the mixture exploded. (a) How many cubic centimeters of aqueous
vapor are formed? (b) What gas and how much of it remains in excess?

14. (a) What weight of water can be formed by the combustion of 100 L
of hydrogen, measured under standard conditions? (b)What volume of
oxygen would be required in (a)? (c)What weight of potassium
chlorate is necessary to prepare this amount of oxygen?

15. What weight of oxygen is present in 1 kg. of the ordinary hydrogen
dioxide solution? In the decomposition of this weight of the dioxide
into water and oxygen, what volume of oxygen (measured under standard
conditions) is evolved?

CHAPTER V

THE ATOMIC THEORY

~Three fundamental laws of matter.~ Before we can gain any very definite
idea in regard to the structure of matter, and the way in which
different kinds of substances act chemically upon each other, it is
necessary to have clearly in view three fundamental laws of matter.
These laws have been established by experiment, and any conception which
may be formed concerning matter must therefore be in harmony with them.
The laws are as follows:

~Law of conservation of matter.~ This law has already been touched upon in
the introductory chapter, and needs no further discussion. It will be
recalled that it may be stated thus: _Matter can neither be created nor
destroyed, though it can be changed from one form into another._

~Law of definite composition.~ In the earlier days of chemistry there was
much discussion as to whether the composition of a given compound is
always precisely the same or whether it is subject to some variation.
Two Frenchmen, Berthollet and Proust, were the leaders in this
discussion, and a great deal of most useful experimenting was done to
decide the question. Their experiments, as well as all succeeding ones,
have shown that the composition of a pure chemical compound is always
exactly the same. Water obtained by melting pure ice, condensing steam,
burning hydrogen in oxygen, has always 11.18% hy