The Atmosphere in relation to Malaria. 219 



organic matter, which existed in the air. Impressed with 

 the idea, that sulphuric acid was a delicate test of the 

 presence of organic matter in the atmosphere, on his de- 

 parture to America, he consulted M. Humboldt, who 

 approved highly of the suggestion. When in company 

 with M. Rivero, he arrived on the hanks of the lake Tari- 

 cagua, the dry season had set in, the waters of the lake 

 had greatly subsided ; the ground, which had been inundated 

 by the rains, was now emitting abundance of effluvia, and 

 dire fever raged among the unfortunate natives. Thus was an 

 excellent opportunity presented of ascertaining the accuracy 

 of the opinion in reference to the agency by sulphuric acid. 

 A quantity of very pure acid was, therefore, exposed to the 

 air for 12 hours. At the termination of that period it had 

 acquired a deep black tinge. No inference could, however, 

 be deduced from this experiment, because the striking 

 effect which he observed might be produced by the numer- 

 ous insects which swarmed in the air. 



In 1829, he operated in a different manner. He was then 

 at Cartago, in the valley of the river Cauca, which in its 

 sluggish course gives origin to several Lagoons, from 

 whence, during the prevalence of the south wind, the 

 malaria is propelled to the town, and produces abundance 

 of disease : such was the state of matters when Boussingault 

 visited the place. A little after sunset, he placed two 

 watch glasses on a table in the middle of a marshy meadow. 

 Into one of the glasses he poured warm distilled water, in 

 order to moisten its surface, and to raise its temperature 

 above that of the air. The other glass being cold was 

 speedily covered with dew, the warm glass received no 

 condensed liquid. When a drop of distilled sulphuric acid 

 was added to each glass and evaporated by the heat of a 

 spirit lamp, a trace of carbonaceous matter was always 

 detected in the dew glass, while none was observable after 

 volatilizing the acid alone. He repeated his experiments, 

 during several evenings, but was then laid on a bed of 

 sickness, by the agency of this very substance which he 

 was endeavouring to detect. These trials shewed the 

 presence of organic matter; the next object was to ascer- 

 tain its quantity. Admitting that miasma as other 

 organic substances contained hydrogen, he considered that 



