CHEMICAL SCIENCE. 293 



animals. The carbonates of lime and magnesia set free during the slow 

 decomposition of the primitive rock, would also go to augment the propor- 

 tion of carbonates in the ocean, and help to f\x in mineral masses the car- 

 bonic acid of the atmosphere. 



At length we reach the carboniferous period of the earth's history, when a 

 luxuriant vegetation completed the work of purifying the atmosphere, by 

 transforming, as Brongniart long since suggested, the remaining excess of 

 carbonic acid into carbon and oxygen gas, thus preparing the air for the 

 support of warm-blooded animals. 



By this hypothesis I think we get a clear conception of the generation 

 from a primeval homogeneous mass of the quartzose, argillaceous and calca- 

 reous materials which make up the bulk of the stratified rocks, and we obtain 

 at the same time a notion of the origin of the saline constituents of the sea. 

 T. Sterry Hunt, Com. to Silliman's Journal. 



EFFECTS OF CARBURETTED HYDROGEN ON PLANTS. 



The recent proceedings of the Philadelphia Academy contain a detailed 

 statement of the effects of carburetted hydrogen gas on a collection of exotic 

 plants, as experienced in an extensive greenhouse in Philadelphia, through 

 the breakage of the city "mains " and the consequent leakage of a large 

 quantity of gas. As a general result of the accumulation of gas, a collection 

 of plants, numbering near three thousand, was almost entirely ruined. The 

 plants not in leaf did not suffer, nor did a row of maple trees immedi- 

 ately over the leak; the injury sustained being entirely through their breath- 

 ing organs. The effect produced upon the plants is detailed at length, a 

 classified catalogue being given, with remarks upon each. In this list it 

 seems apparent that the general sympathy known to exist between the gen- 

 era of the same natural order extends to the action of this deleterious sub- 

 stance upon them. The beautiful Amantiaceee were so keenly sensitive to the 

 poison that even large old specimens were stripped at once. The stage was 

 covered with the leaves, and oranges and lemons in all stages of growth, 

 from fruit just formed to that fully matured. The trees, by careful pruning 

 and nursing, were somewhat restored. Camellia were in the full glory of 

 bloom, about one hundred and twenty varieties. Not a leaf, bud, flower, 

 or woodbud remained upon the largest and finest plants ; and at the slight- 

 est touch the leaves fell off in showers. 



25* 



