CONTENTS.

PART I.

Page

Carbon a Compound Body made by Plants in quan-tities VARYING WITH THE CIRCUMSTANCES UNDER

WHICH THEY ARE PLACED :—

Carbon ..». 1

On the production of carbon by plants. 3

Carbonic acid one source of carbon . 8

Of fertile land. 13

Of inferior land . 17

Of bad land. 19

Of meadow land. 22

Evidence in support of carbon being derived from the at-mosphere . 30

Production of carbon by plants. 60

Plants impart to the air more carbon than they receive from it 74Plants do not increase their quantity of carbon when carbonicacid is removed from the atmosphere in which they grow.. 81Influence of carbonic acid in the atmosphere upon the growth

of plants .. 87

Increase of carbon in plants is not equal to that which dis-appears from the atmosphere. 91

What becomes of the carbonic acid which disappears from the

atmosphere during the growth of plants .101

The carbonic acid which proceeds from combustion.112

The carbonic acid given off by animals during respiration and

perspiration.113

Carbonic acid given off during fermentation and the decay of

organic matter.115

Carbonic acid given off from volcanoes, fissures of the earth,

and water springs .116

The proportions in which plants make carbon under variouscircumstances . 120