CALCAREOUS MANURES— APPENDIX. 285 



NOTE VII. — Extension of subject from pp. 67 and 140. 



RECENTLY OBSERVED POWERS OP CALCAREOUS EARTH, FOR INCREASING THe" PRO- 

 DUCTIVENESS OF LAND AND THE HEALTHFULNESS OF THE ATMOSPHERE. 



It was stated at pages 103-4, that though the practical results of applica- 

 tions of calGareous manures conformed strictly to the theory of their action as 

 previously laid down, yet they exceeded the measure or amount of effect 

 which would have been anticipated from the theory alone. Since a 

 large portion of this work has been printed, I have first lieard of the dis- 

 covery, by Dr. William L. Wight, of Goochland, of a before unknown pro- 

 perty of calcareous earth, wh'ch operates to increase in an important 

 degree its fertilizing power, and also its health-preserving power. I was 

 favored by a mutual friend with the perusal of a rough draught of an essay 

 in which these views were incidentally presented, and which Dr. Wight 

 had designed for publication in a medical journal. I immediately re- 

 quested him to communicate these particular and interesting views, in such 

 form as would suit agricultural and general readers, for publication in the 

 Farmers' Register. To this he assented ; and I had hoped before this time 

 to have. been enabled thus to present the article entire to the public, in 

 which case, it might here be merely referred to, as already in the possession 

 of my readers. The communication has been received ; but> too late to be 

 included in the few remaining pages of the current volume of the Farmers' 

 Register, or to precede the appearance of this note ; though it will appear 

 at length in the first number of the second series of that journal. 



Before stating the newly discovered powers above referred to, it is 

 necessary to introduce them by some general statements of established or 

 received opinions of vegetable and animal life and functions. 



The atmosphere is composed mainly of oxygen and nitrogen gases, 

 (and which two alone are deemed essential to the constitution of atmo- 

 spheric air) with a very small but universally occurring admixture of 

 carbonic acid gas. The oxygen gas (formerly termed " vital air," from its 

 admitted quality,) is that part of the atmosphere which is essential to the 

 life of breathing animals, and which is diluted to form atmospheric air by the 

 mixture of nitrogen gas, and also by the small and perhaps accidental, but 

 always present carbonic acid gas, either of which alone is not only incapa- 

 ble of supporting life, but to breathe which is deadly, and immediate in its 

 fatal effects. Hence it has been supposed, and it is difficult to deny the 

 positions, that to give larger supplies of oxygen gas to the atmosphere must 

 render it more healthful, and to increase the quantity of carbonic acid gas 

 must render it less so. It must be admitted, however, that these deductions, 

 though in accordance with the known and opposite qualities of these 

 different gase.^i, and with reason, are not sustained by the analyses which 

 have been made of atmospheric air in various places. For if these analyses 

 are to be entirely confided in, they would show that in all situations, the 

 highest or the lowest, the most pure and healthy and the most pestilential and 

 fatal to human life, the proportion of oxygen in the air is precisely the same. 



By the respiration of animals, the atmospheric air is partially decom- 

 posed, and the relative amounts of its ingredients altered, at least for the 

 time. Some of the oxygen gas of the air inhaled is retained by the lungs and 

 given to the blood ; and some nearly formed carbonic acid gas is given out 

 from the lungs continually, and added to the atmosphere. Thus, the breath- 

 ing, or the existence of animals, if acting alone, or not counteracted, would 

 serve continually to deteriorate the purity of the atmosphere, and to render 

 it less conducive to the support of healthy animal life. 

 . 36 " 



