1846.] Water, its Properties and Uses. 61 



safely consider those proximate vegetable substances, which con- 

 sist of carbon and the elements of water, as actually compounds 

 of carbon and water. 



Water is then a highly essential part of the vegetable economy, 

 and enters largely into the composition of plants. Its chemical 

 relations are however far more extensive than we have thus far 

 seen. Almost every change which takes place in the soil or in 

 the plant in preparing food or appropriating it to these purposes 

 of nourishment, are more or less dependant upon this fluid. In- 

 deed without this, or some other substance capable of supplying 

 its place, all solid matter must remain almost unchanged and in- 

 active. It is to its solvent power that the vast and varied changes 

 constantly taking place around us and within us are owing. 

 Let us examine for a few moments this power. 



Water is capable of absorbing gases and many solids. Oxu" 

 readers need not be informed, in this age of scientific knowledge, 

 that the food of plants is mostly derived from the air and earth in 

 a liquid form, and that that portion which the roots absorb from 

 the earth is necessarily liquid. The leaves may imbibe gases, as 

 such — the roots cannot. Here water is absolutely necessary to 

 render them available as food. The power of absorbing different 

 gases varies much. Thus water will absorb more than its own 

 bulk of carbonic acid, and more than six hundred times its bulk 

 of ammonia, and is thus capable of supplying a large amount of 

 food to growing vegetables. In the form of rain descending from 

 the clouds it absorbs the gases which have mingled with the at- 

 mosphere, and carries them down to the roots of plants. In this 

 manner it purifies the air for our use, while it affords nom-ishment 

 to the vegetable world. 



It is not in the form of water alone that it is capable of ab- 

 sorbing these gases, but it is found that in the form of ice and 

 snow it absorbs them with astonishing rapidity. A certain quan- 

 tity- of ammonia is generally found in freshly fallen snow. This 

 fact was first noticed by Liebig, and has since been confirmed by 

 numbers of others. The quantity will of com"se vary with the 

 amount of that o-as in the atmosphere at the time of the falling 



