AND PREVENTION OP MALARIA. 225 



greater amount of exhalations. " If the soil is very alka- 

 line aud moist, the conversion of the organic matter into 

 amraoniacal compounds is very rapid. I put some soil 

 not very rich in organic matter into this condition by the 

 assistance of a little ammonia, so as to make it alkaline, 

 and the consequence was the rapid occurrence of a very 

 intense putrefactive decomposition, not in any way differ- 

 ing, as far as could be perceived, from that of ordinary 

 putrefaction of animal and vegetable matter. These nau- 

 seous and unwholesome odours are therefore possible from 

 the ordinarj^ soil of our fields ; but any occurrence such as 

 this on a large scale would be disastrous, and the ground 

 is protected from it by an almost constant acidity, which 

 sometimes increases so as to be injurious, forming what is 

 called sour land. This very acid state generally occurs in 

 wet land, where it is probable that alkalinity would be 

 most injurious, but the soil may be found alkaline in a 

 well-manured garden, and where the ground is dry, 

 without apparent injury.'^ — Author's Report on Air and 

 Water of Toivns, British Association 185 1, p. 69. 



In this experiment I produced in fact artificial malaria. 

 The conditions were exactly such as the best observers 

 have in most cases described, with the addition of the 

 alkaline state, which will probably be found to play a very 

 important part, but which as far as I know has not been 

 attended to. Not that I say that it is impossible to have 

 malaria without ammonia, but ammonia is the wing on 

 which some of the products of decomposition seem to 

 delight to fly. This experiment, which brings the usual 

 condition of warmth and moisture, shows that there may 

 be many modes by which the organic matter in land may 

 pass from the soil besides the transformation into plants, 

 and besides simple oxidation. The decomposition spoken 

 of shows that from soil numerous products may arise. If 

 we allow that putrefaction begins we knov.' no end to the 



SER. III. VOL. I. GG 



