ANALYSIS OF WATER. 



the constituents, and consists in showing, that by combining these 

 constituents water may be produced. 



The method by analysis presumes the previous discovery of some 

 physical agent capable of overpowering the mutual attraction by 

 which the constituents of water are held together, and tearing 

 them asunder, and exhibiting them separated one from the other, 

 so that their characters and properties may be ascertained. 



Since the question itself is of the very highest interest and 

 importance, and since both the methods of synthesis and analysis 

 are in themselves most instructive and easily intelligible, we shall 

 here explain them. 



36. There are two airs or gases known to chemists, and denomi- 

 nated oxygen and hydrogen. 



A general idea of oxygen and its leading properties has been 

 already given in our Tract on Air. 



Hydrogen, like gases in general, is an invisible colourless air, 

 which when perfectly pure is without taste or odour. But as 

 commonly produced it is mixed with very minute proportions of 

 impurities, which impart to it a peculiarly disagreeable odour, 

 with which every one is rendered familiar by the occasional 

 leakage of the pipes used for gas-lighting. 



37. This gas is the lightest of all material substances, being 

 bulk for bulk more than fourteen times as light as common air. 



38. For this reason it is eminently fitted for the inflation of air- 

 balloons. Two thousand cubic feet of this gas will weigh only 

 about 11 Ibs., while the same volume of common air will weigh 

 about 160 Ibs. A balloon, therefore, which would contain 2000 

 cubic feet of hydrogen would have a buoyancy or tendency to 

 ascend, amounting to 149 Ibs., and if the silk bag, cordage, and 

 car, with its load, have less than this weight, it will have an 

 ascensional force equal to the excess. 



39. Hydrogen is one of the most inflammable bodies in nature. 

 It burns with a very pale bluish flame, giving very little light, 

 but intense heat. 



40. If a mixture of oxygen and hydrogen gases be introduced 

 into a strong glass vessel, and be shut into it by closing the stop- 

 cock in the pipe by which the gases are introduced, an electric 

 spark transmitted through the mixture will inflame the hydrogen 

 gas, and an explosion will take place, after which the glass vessel 

 will appear to be filled with vapour, and will acquire an increased 

 temperature. When, after a short interval, it cools, the inside 

 surface of the glass will appear to be bedewed. "Water will trickle 

 down the sides. A certain quantity of gas will remain in the 

 vessel. If this gas be examined by the usual tests it will be found 

 that it is no longer a mixture of oxygen and hydrogen, but is one 



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