418 PLANTS AND THE ATMOSPHERE. 



and to which rarity may possibly be assigned the depreciation of the 

 former study, now too general, yet hardly to be wondered at, when 

 we see the hopeless floundering of metaphysicians of the Hamilton 

 kind over problems which a sprinkling of mathematics would at once 

 dissolve. In conclusion, Senor Lievano will permit us to stretch a 

 hand to him across the equatoi% and greet him heartily and with all 

 good wishes for success, as a fellow-laborer in the field of knowledge. 



J. B. C. 



PLANTS AND THE ATMOSPHERE. 



BY M. J. JAMIN. 



{^Translated from the ^^ Revue des deux Mondes," Sept. 15, 1864.) 

 Those "who have not. devoted themselves to the physical sciences will pardon 

 me if I take the liberty of reminding them that the air, in the midst of which 

 plants and animals live, is a mixture of two very different gases. One, almost 

 inert and without any appreciable influence upon natural phenomena, is called 

 nitrogen. The other, on the contrary, possesses most active properties and 

 plays the foremost part in the maintenance of life upon the globe: this is oxygen. 

 Among other properties, it has that of forming an intimate union with carbon, 

 and during this union, or to employ the seientifie term, while this combination is 

 bein" effected, a considerable quantity of heat and light is evolved. "We say that 

 carbon burns ; and it might, at first sight, be thought to be annihilated ; but 

 really it only transforms itself into a gas, which mingles wfth the atmosphere, in 

 which latter chemistry recovers, at the same time, all the carbon which has been 

 burnt and all the oxygen which has united with it. The name of carbonic acid 

 has been given to this compound gas, in order to recall its origin and composition. 

 Wood, which is essentially composed of carbon and water, burns in the same 

 manner by abandoning the water, which evaporates, and by transforming the 

 carbon into carbonic acid. Fruit, vegetables, bread, all nutritive substances 

 having a chemical composition analogous to that of wood may, like it, be burned 

 in a furnace, and Lavoisier informs us that the substance of these articles of 

 nutrition undergoes a real but slow combustion in the respiratory system of the 

 animals which feed upon them. Every animal, then, is a furnace; every nutritive 

 substance, a combustible ; in respiration, oxygen is absorbed from the air, it is 

 replaced by carbonic acid and the water is rejected either by natural channels or 

 by exhalation. 



" Since carbonic acid is necessarily generated by animal life, it ought, undoubt- 

 edly, to form an integral part of our atmosphere. Accordingly, chemists find it 

 there, but in the minute proportion of from four to five in ten thousand. It is a 

 gas which is incapable of maintaining either life or combustion, being, on the 

 contrary, the effect of both. Thus, all animals placed in a receiver filled with air 



