CHEMICAL SCIENCE. 239 



Malaria has unquestionably been proved to be caused by the decom- 

 position of organized bodies. If so, it must exist to some extent 

 everywhere. By the mode of testing the air invented by the author, 1 

 every place tried at home and abroad was found to have some oxid- 

 izable matter in it, although in some this was extremely small. In 

 such cases the matter was probably oxidized to a state in which it 

 would be innocuous. This oxidizable matter no doubt rises, in a 

 great measure, from vegetation. Vegetation does not merely grow ; 

 it dies. This death may be caused by various circumstances, but 

 two conditions are remarkable : one where the agents are animals, 

 and the other where the agents are chemical. Animal life may act 

 in various amounts on vegetation in the soil, from the large vermin 

 to the microscopic classes. These do not prevent chemical action ; 

 on the contrary, it is probable that they further it exceedingly. De- 

 composition goes on in the soil at various rates, and in various ways. 

 In a rich, highly-manured soil, kept warm, the soil will be found alka- 

 line. Soils generally are acid. The author has shown, in a paper 

 published in 1847, that in an alkaline, peaty district, cold weather 

 produced acidity in a few days. It would appear as if the acids of 

 the moulds (so elaborately described by Mulder) were incapable of 

 further decomposition in the cold, and were thus retained and in- 

 creased. Our great struggle with the soil is to produce alkalinity, 

 or at least to diminish acidity, and where most acids exist we use 

 most limp. Where most alkali exists there is a greater facility for 

 the escape of vapors such as we suppose to be hurtful. So far as 

 the vapors of putrid substances have been examined by the author, 

 they have shown indications of containing substances composed some- 

 what like protein ; at least their carbon and nitrogen have rela- 

 tions to each other similar or nearly identical with those found in 

 protein. 



The extreme condition of putrescence may be very readily pro- 

 duced in a soil by artificial means ; the use of a little ammonia, for 

 example, more than vegetation will bear. The substances putrefy 

 until the whole becomes fetid in the highest degree. We have then 

 a soil rich in organic matter and undrained. It is a swamp of the 

 worst form if the soil be not very poor ; worse, perhaps, than was 

 ever seen in nature. Such a soil would bring death everywhere. It 

 is artificial malaria. We can, then, produce malaria from the soil by 

 fostering some of its tendencies ; and we see by the rapid acidifica- 

 tion of soil in colder weather why malaria is diminished by a lower 

 temperature. 



As we can imitate malaria of some kinds, so can we also imitate 

 the methods by which nature prevents it. The warm alkaline soil, 

 moistened, and washed with air and water, becomes acid ; it sends 

 forth less volatile matter ; decomposition is stopped to a great extent ; 

 the matter is preserved. Cold prevents the action, drainage assists 

 oxidation by a more active state of soil. By these modes and others 

 the soil is olisinfected by nature ; when these do not act sufficiently, 

 we may use disinfecting agents. By their means decomposition may 

 be interrupted without fear of diminishing the power of the plant to 



1 See Annual Sci. Dis., 18GO, p. 239. 



