TEMPERATURE. 151 



admixture increases the volume of air, and diminishes its specific 

 gravity; as an inference, warm damp air contains less of the 

 respirable element than any other. The warmer the atmosphere 

 the larger the quantity of water which it can hold in suspension. 

 A damp atmosphere the temperature being equal, or even 

 greater produces a peculiar feeling of chill, widely differing 

 from the bracing effect caused by a cold, dry air. The sensation 

 produced by the former is keener, and seems to penetrate 

 the whole system, thereby producing chilliness and involuntary 

 shivering from within, with a bluish paleness externally ; in fact, 

 a damp atmosphere acts by diminishing the power of producing 

 heat, and the symptoms evinced very much resemble those of 

 an incipient attack of intermittent fever. 



The influence of a damp, warm atmosphere on the various 

 functions is still more distinctly observable than that of a dry, 

 warm air. The proportion of the colouring matter decreases in 

 the blood, thereby showing that hematosis is modified by humidity. 

 As a result of these modifications of the blood, the different 

 organs are variously affected, and, among others, the stomach : 

 its digestive power is weakened, and, generally, a lesser proportion 

 of food is required to satisfy the appetite gentle stimulants and 

 tonics then become necessary. 



The hepatic secretion is much diminished, and the quantity of 

 bile secreted may not only become insufficient for the process of 

 healthy digestion, but even its very quality may become so much 

 altered as to constitute a pathological state. As a consequence of 

 the alterations caused in hematosis, and the digestive functions, 

 nutrition becomes impaired. 



The glandular system is, also, particularly modified, its activity 

 is much increased, and individuals, having lived for a certain 

 period in a damp locality, may be said to be placed under the 

 same conditions as those who are of a lymphatic temperament. 

 If, together with these natural coincidents, are combined those of 

 insufficient non-animal diet, bad lodgings, and the appurtenances 

 of filth, the consequences speedily become apparent : inflamma- 

 tion of the lymphatic glands and vessels, ulcers, chronic exema, 

 and even leprosy, according to individual constitution, must be 

 the deplorable results. 



Light. It is not very easy to obtain practical information as 

 to the influence on man of this physical agent, when considered 



