DECOMPOSITION OF SALINE BODIES. jgj 



ments, all of which might have been quoted as examples of the observations which I 

 wish to deduce from it. 1st. They all coincide in this respect, that the oxygen is never 

 evolved without the simultaneous appearance of nitrogen. 2d. That when certain 

 leaves are employed, as those of the Pinus tada, there seems to be a very simple rela- 

 tion between the volumes of oxygen and nitrogen. In the first and second of those ex- 

 periments, the volume of the oxygen is to that of the nitrogen as two to one ; in the third, 

 as one to one. In certain cases this apparent simplicity of proportion is departed from; 

 but from its frequent occurrence in many analyses I have made, it seems to demand at- 

 tentive consideration. Moreover, in other plants, as in experiments 4 and 5, the amount 

 of oxygen is relatively greater, and between it and the nitrogen there does not appear 

 any exact proportion. 



800. In order to ascertain whether decompositions taking place under absorbent me- 

 dia, as bichromate of potash, produce the same results as indicated in the foregoing ta- 

 ble, I made several analyses of gas collected under these circumstances. The presence 

 of the absorbent medium did not seem to exert any influence whatever, the general re- 

 sults coming out as though it had not been employed. 



801. It has long been a matter of popular observation that the sunlight has the qual- 

 ity of extinguishing domestic fires. I do not know whether there is in reality any 

 ground for this opinion ; or if so, whether the phenomenon is in any way connected 

 with the relations of light to carbon and oxygen. Popular opinion ascribes the effect 

 to the light, and not the heat of the ray. To determine whether radiant heat, unaccom- 

 panied by light, had the power of producing the decomposition of carbonic acid through 

 the agency of leaves, I placed in the focus of a large brass concave mirror a vessel con- 

 taining some pine leaves in carbonated water. The mirror was set before a wood fire, 

 and after a little time the leaves began evolving bubbles. The temperature of the wa- 

 ter rose as high as 140 Fah., and when sufficient gas was collected, examination proved 

 that nearly the whole of it was absorbed by lime or potash water. From this, it is 

 evident that radiant heat merely liberates the carbonic acid, and does not decompose 

 it. This corroborates, therefore, the result of the prismatic analysis, that it is the light, 

 and not the heat, which brings about the change. 



802. Decomposition of Alkaline Salts. The conditions under which carbonic acid 

 gas is decomposed being understood, I pass now to the description of similar decompo- 

 sitions occurring in the case of saline bodies. It has always been a subject of surprise 

 to chemists, that the powerful affinity by which carbon and oxygen are held together 

 should be so easily overcome at common temperatures. Even potassium cannot de- 

 compose carbonic acid in the cold. It might, therefore, be reasonably expected that the 

 energetic forces which bring about this change ought also to effect other remarkable 

 decompositions. In fact, as I shall now proceed to show, the decomposition of carbonic 

 acid is only one of a very numerous series. 



803. The alkaline bicarbonates, as is well known, undergo decomposition by a slight 

 elevation of temperature. When boiled with water they gradually give off their second 

 atom of acid, and slowly pass into the condition of neutral carbonate. This easy de- 

 composibility led me to inquire whether green leaves, under the action of the sunlight, 



