SANITARY ESSENTIALS. 315 



Under the direction of the privy council, Dr. Siraon made 

 an extensive and elaborate investigation of this subject ; and 

 he remarks, that "it confirms, without any possibility of 

 question, the conclusion previously suggested, — that damp- 

 ness of soil is an imjjortant cause of phthisis to the popula- 

 tion living upon the soil." 



In the Seventh Report of the Massachusetts State Board 

 of Health, Dr. Winsor remarks, after investigating the drain- 

 age of a hundred and twenty-eight towns in Massachusetts, 

 that "no observer can doubt that a large amount of pre- 

 ventable disease is caused by damp cellars." 



The theory of soil-moisture as one of the active causes of 

 consumption through the medium of the air is so confirmed 

 by evidence from different parts of the world, that it may 

 now be regarded as a well-established fact, 'pregnant with a 

 si(jyiificance that cannot he over-estimated. 



Lord Bacon has said, "He who builds a fair house on an 

 ill seat committeth himself to prison." 



Air is essential to the life of all organized beings. It is 

 composed of a somewhat changeable mixture of invisible 

 gases. About twenty per cent of oxygen, seventy-nine per 

 cent of nitrogen, and four-hundredths of one per cent of 

 carbonic acid, constitute a normal atmosphere capable of 

 sustaining vegetable and animal life, in so far as this life 

 depends on atmospheric conditions. 



Air is rendered impure from various causes. It carries 

 odors, miasms, the gaseous products of animal and vegetable 

 decomposition, dust, dirt, sand, saline matters, the pollen of 

 plants, poisonous animal and vegetable exhalations, the germs 

 of epidemic diseases (such as measles, scarlet-fever, and small- 

 pox), and the varied products of combustion. Dead, confined, 

 stagnant air becomes rapidly impure, and unfit for respira- 

 tion. In nature, air is constantly kept in motion through the 

 action of heat, cold, and electricity, and is purified by mov- 

 ing over large bodies of water, by diffusion and oxidation, 

 storms and vegetation. Its most important constituent is 

 oxygen, without which all organized beings would perish ; 

 while at the same time it is the most destructive agent in 

 nature of all organic forms. It combines readily Avith all 

 elementary bodies except fluorine. 



An atmosphere of pure oxygen would be speedily fatal to 



