trifluoride), SiF_{4}
(silicon tetrafluoride), PF_{5} (phosphorous pentafluoride), SF_{6}
(sulphur hexafluoride) and probably others. In other words, the
fluorides of all the non-metals that can form fluorides. The
phosphorous pentafluoride rains out when the weather gets cold. There
is also free oxygen, but no chlorine. That would be liquid except in
very hot weather. It sometimes appears combined with fluorine in
chlorine trifluoride. The atmosphere has a slight yellowish tinge.

3. SOIL AND GEOLOGY

Above the metallic core of the planet, the lithosphere consists
exclusively of fluorides of the metals. There are no oxides, sulfides,
silicates or chlorides. There are small deposits of such things as
bromine trifluoride, but these have no great importance. Since
fluorides are weak mechanically, the terrain is flattish. Nothing
tough like granite to build mountains out of. Since the fluoride ion
is colorless, the color of the soil depends upon the predominant metal
in the region. As most of the light metals also have colorless ions,
the colored rocks are rather rare.

4. THE WATERS UNDER THE EARTH

They consist of liquid hydrofluoric acid (HF). It melts at-83 deg.C and
boils at 19.4 deg.C. In it are dissolved varying quantities of metallic
and non-metallic fluorides, such as boron trifluoride, sodium
fluoride, etc. When the oceans and lakes freeze, they do so from the
bottom up, so there is no layer of ice over free liquid.

5. PLANTS AND PLANT METABOLISM

The plants function by photosynthesis, taking HF as water from the
soil, and carbon tetrafluoride as the equivalent of carbon dioxide
from the air to produce chain compounds, such as:

H H H H
| | | |
--C--C--C--C--
| | | |
F F F F

and at the same time liberating free fluorine. This reaction could
only take place on a planet receiving lots of ultra-violet because so
much energy is needed to break up carbon tetrafluoride and
hydrofluoric acid. The plant catalyst (doubling for the magnesium in
chlorophyll) is nickel. The plants are colored in various ways. They
get their metals from the soil.

6. ANIMALS AND ANIMAL METABOLISM

Animals depend upon two main reactions for their energy, and for the
construction of their harder tissues. The soft tissues are about the
same as the plant molecules, but the hard tissues are produced by the
reaction:

H H H F F F
| | | | | |
--C--C--C-- +