and undergoes transformation into more stable
combinations. This modification would not, in any essential way, be at
variance with the atomic theory as propounded by Dalton.

EXERCISES

1. What properties have the alkaline-earth metals in common with the
alkali metals? In what respects do they differ?

2. Write the equation for the reaction between calcium carbide and
water.

3. For what is calcium chlorate used?

4. Could limestone be completely decomposed if heated in a closed
vessel?

5. Caves often occur in limestone. Account for their formation.

6. What is the significance of the term fluorspar? (Consult dictionary.)

7. Could calcium chloride be used in place of barium chloride in testing
for sulphates?

8. What weight of water is necessary to slake the lime obtained from 1
ton of pure calcium carbonate?

9. What weight of gypsum is necessary in the preparation of 1 ton of
plaster of Paris?

10. Write equations to represent the reactions involved in the
preparation of strontium hydroxide and strontium nitrate from
strontianite.

11. Write equations to represent the reactions involved in the
preparation of barium chloride from heavy spar.

12. Could barium hydroxide be used in place of calcium hydroxide in
testing for carbon dioxide?

CHAPTER XXV

THE MAGNESIUM FAMILY

===========================================================================
|SYMBOL |ATOMIC |DENSITY |MELTING |BOILING | OXIDE
| |WEIGHT | | POINT | POINT |
---------------------------------------------------------------------------
Magnesium | Mg | 24.36 | 1.75 | 750 deg. | 920 deg. | MgO
Zinc | Zn | 65.4 | 7.00 | 420 deg. | 950 deg. | ZnO
Cadmium | Cd |112.4 | 8.67 | 320 deg. | 778 deg. | CdO
===========================================================================

~The family.~ In the magnesium family are included the four elements:
magnesium, zinc, cadmium, and mercury. Between the first three of these
metals there is a close family resemblance, such as has been traced
between the members of the two preceding families. Mercury in some
respects is more similar to copper and will be studied in connection
with that metal.

1. _Properties._ When heated to a high temperature in the air each of
these metals combines with oxygen to form an oxide of the general
formula MO, in which M represents t