42 WATER. 



obtained from the flowers or bark. There are few 

 plants in which a careful examination of their various 

 parts will not discover from fifteen to twenty different 

 organic substances, and in some twice that numbei 

 may be distinguished. The perfect separation and 

 determination of such bodies, is among the mast diffi- 

 cult of problems of modern chemistry. But after all, the 

 substances which make up the great bulk of plants 

 are few in number. Those which give the color, 

 taste, smell, or peculiar properties of that kind, to 

 particular plants, generally form but a small part of 

 their whole mass, and have but little influence on 

 their practical value. 



SECTION III. OF WATER. 



In order to explain some remarkable propeities in 

 the substances to wdiich attention will soon be called, it 

 is necessary here to mention the composition of water. 



This liquid, so universally diffused and of such in- 

 estimable value, is composed of but two gases, oxygen 

 and hydrogen. In nine pounds of water, are about 

 one of hydrogen and eight of oxygen. Although the 

 weight of oxygen is thus greatest, hydrogen is so 

 light that it constitutes the greatest bulk, so that by 

 measure there is only one gallon of oxygen to two of 

 hydrogen. 



a. That water does consist of these two gases alone, 

 may be shown by burning hydrogen in an atmosphere 

 of oxygen. Water will immediately begin to con- 

 dense on the sides of the vessel used by the experi- 

 menter, and will soon accumulate so as to run down 

 in drops. Some of the French chemists once tried 

 this experiment on a large scale, continuing it for a 

 number of days, and obtained several pints of water 

 On burning a jet of hydrogen in common air, under 

 a large glass vessel open at bottom, water will irame- 



