No. 216.] 751 



Judge Van Wyck. I believe that Dr. Underhill is right to some 

 extent, in his theory. Good rich soil will retain the rising gases for 

 some time, for the use of plants; it also retains the moisture, but 

 when it is exposed for a time to a hot sun, they are drawn out. Mois- 

 ture is indispensable for the solution of the essence of manures. No 

 doubt manures should be put deeper in loose porous soils than in 

 more compact ones. Still the depth of manures must te suited to 

 the peculiar wants of plants, as to depth, &c. 



Mr. Hall. If the gases escape from the soil, are they lost? Do 

 they ascend to heaven, or return to the earth for the benefit of plants? 



Dr. Underhill. Yes sir, they do ascend, and on the shores of the 

 Atlantic may be wafted to enrich the ocean: or if near the deserts 

 of Africa, to fertilize them. The elements of manure, the salts, are 

 drawn up near to the surface of soils, but not one quarter, not one 

 half of them, escape in the form of gas. 



Mr. Hall. Carbonic acid gas ascends by day, and descends to 

 soil by night. 



Dr. Underhill. There is about one per cent, of carbonic acid in 

 atmospheric air, and plants consume a portion of it by their leaves. 



Judge Van Wyck. It is well to recollect that in this country 

 droughts are seldom. We have a large proportion of temperate 

 seasons. ' 



Mr. Meigs. We have full opportunity in our greatly increasing 

 city, to examine the subsoils brought to light by the parings and lev- 

 elling of the land. Who has not observed, and I often have, that 

 where a few feet of the rich old surface soil has been taken off, the 

 remaining subsoil was guiltless of all fertility? Not a thousandth 

 of the rich soil, the humus on the surface, since the flood, has de- 

 descended three feet into the subsoil. A barren waste can at any time 

 be made by either paring off a foot or two of the surface of your 

 land, or by the fashionable practice of skinning it by over cropping 

 without any returns of manure. 



Mr. Sherwood, In England we are in the habit of placing raa- 

 nu'-es on the surface, especially in the grazing districts. It is done 

 annually, and is of incontestible benefit. In the south of England 

 they manure in the fall of the year on the surface, and in the spring 



