SCIENTIFIC HISTORY OP A PLANT. 



We must all allow, that this fact of the growth of higlily ligneous plants containin 

 juices in arid plains, is not in favor of an hypothesis that considers vegetable mold as the 

 true source of carbon for plants. 



Besides the property of decomposing carbonic acid, vegetables have also the power of 

 decomposing water; hence the source of hydrogen. At first sight we must imagine that 

 there must be a marvellous energy in the chemical process of vegetation, when able to ef- 

 fect what the electricity of a powerful thunderstorm accomplishes only feebly and imper- 

 fectly: but when we reflect upon the various methods by which water can be decomposed, 

 this feeling is somewhat limited. The metals — some at common temperature, others at a 

 red heat, and the same, or more of them in contact with a strong acid; and, as it has been 

 beautifully shown by Mr. Grove, by heat alone. 



We krow that this action must take place, from the fact that caoutchouc, wax, and oils, 

 contain more hydrogen than oxygen; and we also know that water must be the only 

 source of the hydrogen. The water is decomposed, the hydrogen is taken up into a 

 plant with the green principle of the leaf, which diminishes in quantity when oxygen is 

 absorbed. Plants containing water and carbonic acid, and evolving only a little oxygen, 

 give an acid, — evolving more oxygen, they form a neutral substance,^evolving a large 

 amount of ox3'gen they give us an oil. 



Again, chemical analysis pointed out nitrogen as a constituent of plants, and for a long 

 time it was a question how this nitrogen was obtained; later experiments, however, have 

 shown that it has its origin in the ammonia which is always found in the atmosphere. 



It was found that plants would grow in charcoal, or in calcined earth containing not a 

 trace of carbon, if watered with rain water, and this because rain water contains more 

 ammonia — hence its softness. So there are two forms in which this ammonia, so requisite 

 for vegetation, may be found : as a gas existing in the atmosphere, (though this is seldom the 

 case,) and held in solution by water which conveys it to the soil. Agriculturists find that 

 the form in which it is given is of more importance than the actual quantity. Carbonate 

 of ammonia is often found in large quantities; but it is a volatile salt, and for this reason 

 a very considerable qunntity of the ammonia it contains is volatilized and lost. The ob- 

 ject of gypsum as a manure, is to produce that double decomposition by which is formed 

 carbonate of lime and sulphate of ammonia, a more stable compound. 



The source of ammonia exhibits to us one of those beautiful and never ending cj^cles of 

 mutual relationship upon which the mind of the real observer of nature always delights 

 to dwell. Throughout the physical world, from its formation to the present time, there 

 has never ceased to be a perpetual mutation of matter — a ceaseless, ever restless desire for 

 change of form, and after some boundless wanderings, a turning back again, to undergo 

 perchance the same work, though on a different subject — at a great distance from its for- 

 mer one — and after an inconceivably long interval had elapsed. 



" Communion with nature awakens thoughts that had long lain dormant," enthusiasti- 

 cally exclaims the author of the "Cosmos." Surely this sentiment must find within a 

 hearty echo, when for the first time we contemplate — actually by experimental demonstra- 

 tion — the imperishability and the indestructibility of matter: when, as in the case of the 

 combustion of an organic substance with oxide of copper, the sugar, the volatile oil is de- 

 destroyed, but its elements have a.ssumed new forms, rendered cognizant to the senses by 

 the balance. 



It is this great fact which lends to my mind a charm — somewhat ftinciful I must admit 



the science of geology. The thought that the oxygen — as carbonic acid was emitted 



lentifully in the volcanic disturbances of the ancient world — which formed part of its 



