38 REPORT OF NATIONAL MUSEUM, 1884. 



(e) Chemical analysis of the air in the lecture room. 



On several occasions it has been remarked that the air in the lecture 

 room became exceedingly oppressive during the progress of meetings, 

 lectures, &c. In order to verify these statements. Dr. J. H. Kidder, of 

 the United States Fish Commission, was requested by Professor Baird 

 to analyze the air during the progr«ss of some of the Saturday afternoon 

 lectures. Dr. Kidder's notes are here given in full : 



estimation of carbon dioxide in the lecture hall of the 



national museum. 



March 1, 1884. 

 The hall is at the northwest angle of the building and measures 91^ 

 by 49§ feet by 28f feet mean height. 



, Cubic feet 



Total cubical contents 1*30,279.7 



Less space occupied by .500 persons (in cubic feet) 1, 500 



Less space occupied by screens and seats (in cubic feet) 1, 000 



2, 500. 



127.779.7 



The lecture began at 3.30 and continued for three-quarters of an hour; 

 most of the audience were present for a full hour. Its number, as es- 

 timated by the superintendent, was about 500. The hall had been 

 scrubbed and ventilated as well as possible (but very imperfectly) dur- 

 ing the day, and the screens freshly painted. 



Out-door air was damp and cold, slightly below the freezing point. 

 Air of lecture hall, at 9 feet from the floor, about the middle of the hall, 

 was as follows : 



Floor scarcely dry at beginning of lecture. 



Carbon dioxide. — Eighty-six feet of rubber hose, one-quarter inch in- 

 side diameter, were washed for two hours by a continuous stream of tap 

 water and strung upon the gas fixtures from a point 8 feet from the 

 floor, near the center of the hall, to the uppermost room of the north- 

 west tower. Air was i^umped by aspiration through this tube from the 

 hall, and after the residual air in the tube had been displaced, was col- 

 lected in close bottles and examined, with the following results : 



Parts CO2 per 10,000 



March 1, half an hour before lecture 8. 67 



March 1, half an hour after beginning of lecture 12. 22 



March l,air of experiment room 13.04 



February 29, out-door air (4 p.m.) 3. 97 



March 3, out-door air through tube 5.54 



