INTRODUCTION. 



acquainted with the elementary com- 

 ponents of water, or the manner of 

 their union, we will premise, that the 

 atmosphere, which surrounds the earth, 

 is composed of two kinds of air, called 

 oxygen and nitrogen gases, in the pro- 

 portion of one part of the former, to 

 four of the latter ; while water is com- 

 posed of oxygen and hydrogen gases, 

 in the proportion of eight parts, by 

 weight, of the former, to one of the 

 latter. Hydrogen and oxygen gases 

 may be chemically combined, by com- 

 bustion, in the following manner : 

 Let a quantity of hydrogen gas be 

 brought in contact with the flame of a 

 burning candle, in the air, and the 

 oxygen of the atmosphere will combine 

 with the heated hydrogen of the candle, 

 and water will be formed by the com- 



