IMPORTANCE OF THE FOUR ORGANIC ELEMENTS 13 



energy of the oxygen. Being incapable of burning 

 or supporting combustion, it prevents the general con- 

 flagration which would occur in pure oxygen, and also 

 reduces its strength to the proper proportion for sus- 

 taining animal and vegetable life, without bringing in 

 any poisonous or deleterious influences, as many other 

 gases would do. We see then that its negative pro- 

 perties just fit it for its office. 



I have been thus particular in describing simple 

 processes for obtaining these gases, because every mind 

 is better satisfied by direct and practical proofs. The 

 experiments here given are so easy that the most in- 

 experienced experimenter could soon perform them 

 without difficulty. There are few places of any size 

 where the necessary materials and apparatus can not 

 be found, and obtained with little expense. Every 

 teacher should illustrate his explanations by these 

 proofs; thereby impressing an idea of each substance 

 upon the mind more indelibly than could be done in 

 any other way. Many farmers could make them for 

 their own satisfaction in leisure hours. 



The reader will now understand why it is that I 

 have urged the necessity of becoming acquainted with 

 these organic bodies; for he has seen that they not 

 only compose by far the larger proportion of the 

 vegetable world, but that mixtures of two or three of 

 them constitute the air we breathe, the water we drink, 

 and, in one shape or another, a large part of the earth 

 upon which we live. Are not these eminently bodies 

 with which all of every profession ought to be well 

 acquainted; and most of all the farmer, who depends 

 on them under various forms for all success, who can 

 not engage in the most simple operation without being 

 influenced by them in different and most important 

 ways? The man who knows the principal properties 

 and the peculiar energies of the materials with which 

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