All! AND LIFE. 



By Henry de Varigny, M. D., Sc. D. ? - 



Member of the Societe de Biologie, Demonstrator in the Institute of Comparative Pathology, 

 in the Paris Museum of Natural History. 



[Translation (by the author) of the essay on L'Air et la Vie, submitted by Dr. 

 Henry de Varigny in the Hodgkins Fund Prize Competition of the Smithsonian 

 Institution, and awarded "the third prize of $1,000, for the best popular treatise 

 upon atmospheric air, its properties and relationships."] 



CONTENTS. 

 I. — Air from the Physical point of View. 



Weight; Liquefaction and solidification; Height of the atmosphere; Its odor; Its 

 penetration into the soil, into salt and sweet water; Proportion and nature of the 

 gases dissolved in water; Variations according to time and place; River pollution; 

 Role of atmospheric dust in the diffusion of air in water; Ratio of the rapidity of 

 the "respiration" of waters. 



II. — Air from the Chemical point of View. 



Constituents of the mixture called air; Air is a mixture, not a combination; His- 

 tory of the discovery of the constitution of air; Jean Rey, Priestley, Lavoisier; 

 Methods of analysis. 



Oxygen, its origin, role of plants in its production. Nitrogen, its origin. 



Carbonic acid; Variations according to time, place, and conditions; Its sources; 

 Respiratory combustion; Fermentation; Industrial combustion; Mineral springs; 

 Volcanoes, etc. Approximate evaluation of carbonic acid production; Causes of 

 destruction of this gas ; Role of calcareous shelled animals, of plants, of the ocean 

 in the absorption and regulation of carbonic acid in the atmosphere. 



Ozone, its character, amount, variations, probable origin. 



Ammonia, nitrous and nitric acids; Carbureted hydrogen; Sulphureted hydro- 

 gen; Salts, their influence upon the crystallization of supersaturated solutions. 



Hypothetical volatile products exhaled from the lungs; Experiments by Brown- 

 Sequard and d'Arsonval. 



III. — Biological R6le of the Chemical Constituents of the Air. 



Role of oxygen; It is the most important respiratory gas; Average ratio absorbed 

 by man; Respiration of plauts identical with that of animals; Necessity of oxygen 

 for plants at all ages. Toxicity of oxygen in excess or under increased pressure; 

 Apparent uselessness of oxygen for anaerobic organisms; anaerobiosis of animal tis- 

 sue. Active life is not possible without oxygen, free or combined. Role of nitrogen ; 



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