312 THE FARMER AT HOME. 



ture ; there is scarcely a single process, either natural or artificial, in 

 which oxygen has not a share, but it is known only in combination 

 with other bodies. It forms nearly or quite half of the material of our 

 globe. Of every nine pounds of water, eight pounds are oxygen. Of 

 air it forms the one-fifth part. Of the solid ground, nearly one-half is 

 oxygen ; but to make an estimate correctly we must look at the 

 several minerals composing the earth, and then, knowing the amount 

 of oxygen in each one of these, we may have an idea of its amount in 

 the whole. Silica and alumina are more abundant than all the others 

 together ; the former is composed, 24 parts of oxygen, and 22 of sili- 

 con, the latter of 24 of oxygen and 27 of aluminum. Water is an 

 important constituent of nearly all minerals, and being mainly com- 

 posed of oxygen, it helps to enlarge our estimate of the vast amount 

 of this element in the formation of our planet. But its importance is 

 not more conspicuous in its amount than in the part it acts in the ani- 

 mal and vegetable world. Every grown up person consumes 150 

 cubic feet of it in his lungs daily. It unites with the carbon of our 

 bodies, and then we exhale it as carbonic acid gas. How constantly 

 are our lives dependent upon it ! If deprived of it from three to five 

 minutes, our lives are extinct. Drowning causes death simply by 

 depriving us of oxygen. Strangling or choking instantly causes death 

 in the same way. 



When we think of how much oxygen is daily consumed by the 

 800,000,000 people of our earth, by all the myriads of animals, and 

 by all the fires for warming, cooking, and manufacturing purposes, we 

 are astonished at its vast daily consumption ! How shall the air 

 receive a new supply ? Only from the leaves of plants ! They imbibe 

 carbonic acid in the leaves, decompose it, take the carbonic for build- 

 ing up their structures, and give out the oxygen for the support of 

 men and animals. We are just as much dependent upon plants for 

 the air we breathe as for our food and clothing. And plants are 

 equally as dependent on animals for their necessary supplies of car- 

 bonic acid. Plants have this power of absorbing carbonic acid and 

 giving out oxygen only through the influence of the yellow rays of sun- 

 light. At night this mysterious process does not go on, and if with a 

 prism we decompose the rays of the sun, we find that in the yellow 

 rays alone they give out oxygen. Here we see the dependence of one 

 part of creation upon another, and how in fact the w T hole fabric of the 

 known universe is a unity ! No science is complete in itself alone, 

 because no department of creation is disconnected with the other 

 parts. All are mos intimately interwoven, and their greatest beauty 

 and grandeur is seen in their connections and their harmonious 

 operations. Creation is a great machine no portion of it is for an 

 instant at rest. And among all these motions not one is independent. 

 Each is caused by the other in a mazy round, and the grand Power 



