PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 533 



of imbibing, taking up and carrying off the effete carboniferous 

 matters, which, by the vital action, are presented at or near the 

 surface. 



During the spring and early summer, while vegetation is grow- 

 ing luxuriantly, carbon is assimilated and the atmosphere is puri- 

 iied ; but later, when plants begin to decline in their growth, the 

 air becomes charged, in greater proportion, with carl)onic acid. 

 To this, and to the fact that in the latter part of summer and hi 

 the fall the atmosphere is more highly charged with aqueous vai)or, 

 is due to the greater prevalence of malaiious diseases in the fall of 

 the year than in the spring. 



In crowded and badly ventilated hospitals, ships, prisons, &c., 

 the air sometimes becomes charged to repletion with the very mat- 

 ters which ha,ve alread}' served their purpose in the animal 

 economy, where))y disease of malignant type is generated. 



These mutters, it may be. true, when taken into the lungs by 

 inspiration, are, in some degree, poisonous ; but their deleterious 

 effects, in this respect, are next to nothing, compared with those 

 occasioned by their effect in depriving the air of its tendency of 

 absorbing and carrying away the exhaling matters. 



I conclude, therefore, that malarious diseases (not including the 

 contagious) are not caused by the exterior poison taken into the 

 system, but by interior effete excremeutitious matters, which have 

 become poisonous, of which the system has failed to be properly 

 depurated, on account of the lack of a good dry atmosphere, hav- 

 ing affinity or appetency for such excretions, and the consequent 

 depuration of that very important auxiliary in the performance of 

 13erspiratory fimction. 



And now for the remedies, the disinfectants ; and what are 

 they? I answer, anything that has a tendency to desiccate, or 

 dry the air, or to enlarge its capacity of absorbing and dissolving 

 the fluid of perspiration— thereupon " fire," as was quaintly re- 

 marked at our last meeting, "is the best disinfectant." 



The immnnity from malarious attacks enjoyed by persons whose 

 calling keeps them much under the influence of artificial heat is 

 proverbial. Fire greatly increases the power of evaporation in 

 the atmosphere. 



Chloride of calcium and other deliquescent salts, owing to their 

 strong attraction for moisture, tend to dry the air, and are, so far, 

 good— but they are costly and inefiicient as compared Avith a little 

 lire. The conunon practice, therefore, of taking down stoves and 



