504 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



be reduced to the normal amount found in the air without, even 

 by the introduction of any quantity of fresh air. It may, how- 

 ever, be reduced to within the limit of health, that is to say, eight 

 hundredths of one per cent. 



The air of a dwelling may be vitiated by the human breath; by 

 ettiuvia from the human skin, by the products of combustion in 

 the commo]! process of illumination ; by gases escaping from 

 heating apparatus and cooking ranges ; by emissions from poison- 

 ous compounds, like many wall papers containing green colors 

 produced by arsenic; by exhalations arising from damp cellars — 

 and lastly, Ijy the gaseous products of vegetable and animal 

 decomposition. 



The intricate and delicate structure of the organs which receive 

 these deleterious gases will always excite our admiration and 

 wonder. The lungs of an ordinary sized man contain about 

 1,750,000,000 of air cells, and the surface of the membrance is 

 more than 1,500 square feet in extent. In one minute such a per- 

 son would respire from 3 to 400 cubic inches of gas; and in one 

 hour the quantity of oxygen consumed or combined with carbon, 

 would usually reach 1,300 cubic inches. 



The chairman then spoke at some length of the actual necessity 

 of better ventilation of our dwellings. He described the method 

 now used on some of the principle railways, for ventilating sleep- 

 ing cars. The air to be breathed is made to pass through a chamber 

 into which water in fine spray is forced, thus separating the air 

 from dust and all other impurities. The plan first used on cars, 

 for preserving fresh meat brought from the West, which consists 

 in placing ice in the top of the inside of the car, over which the 

 heated air from the outside passes, and, after falling to the floor, 

 is allowed to enter the car and drive otf, through an opening iu 

 the top, the warmest air, thus keeping the meat surrounded with 

 air cooled to near the freezing point. This method, with some 

 modifications, had been used with success in supplying fever hos- 

 pitals with fresh air. 



Mr. T. D. Stetson said, an experiment was tried at a stable in 

 this city, to ventilate the stalls by allowing air to come from the 

 outside down over the horses' heads, but it was found that the 

 horses were always sick with colds and other ailments. This was 

 tried for two years, when the openings were closed, after which 

 the horses were in good health. 



Dr. R. P. Stevens doubted very much the thei)ry advanced at a 



