Proceedings of the Polytechnic Association. 1023 



above observers. But it was only in conditions of considerable 

 intensity that these processes were applicable, and by much trouble 

 and exposure that it could be put in practice. In 1842, experiment- 

 ing on the compounds of manganese, I found, as was already known, 

 that permanganic acid was very unstable, and its salts more or less so, 

 especially when exposed to the air. In testing the effects of various 

 bodies on these compounds, we found some neutral, others hastening 

 tlie process of decomposition. Oxygen, nitrogen and carbonic acid 

 neutral ; ammonia, sulphureted hydrogen, and others, producing 

 instant decomposition. The high intensity of color, compared with 

 the small amount of the material required, gave us the idea of apply- 

 ing it for the detection of our object by special interest. Our hopes 

 were fully realized. By passing air through a solution of perman- 

 ganate by the aid of an aspirator, the minutest quantity could be 

 detected. By a standard solution of permanganate and a given quan- 

 tity of water in the aspirator, the relative quantity of malaria was easily 

 and promptly determined. By attaching a long tube to the bulb 

 containing the solution, the air could be drawn from any particular 

 place ; from swamps, wells, pools, sinks, beds, under houses, &c. By 

 analysis of the contents of the bulbs when they have become colorless, 

 the constitution of the malaria is ascertained. We now have our 

 first query answered : How can malaria be detected ? The answer 

 is, by a permanganate. 



2d. What are the conditions under which malaria is produced ? 



Whenever organic materials are undergoing decomposition, with 

 free access of air, with, a sufficient degree of moisture and a tem- 

 perature from ninety to 100 degrees Fahrenheit, one of the results 

 of decomposition is malaria. It is not in swamps or filthy places 

 alone this element is prodnced, but from every soil that will support" 

 vegetation, and from the emanations of our bodies. We have 

 obtained it from common garden soil hy moistening it and subject- 

 ing it to tlie appropriate temperature ; from the water in which 

 mider clothing has been washed, we have obtained it in great 

 intensity. 



3d. AVliat is the nature of malaria ? On this point the scien- 

 tific world is divided. One,' on which Liebig stands promhient, 

 is what is called the chemical theory. This theory supposes that 

 malaria is a material that is undergoing decomposition, and by 

 contact with highly complex substances, as the blood, produces 

 a change from the normal condition of the blood, thus producing 



