40 



REPORT OF NATIONAL MUSEUM, 1884. 



March 8. 

 Out doors rainy. Lecture began at 3.30 p. m. ; 700 persons present. 



Carbon dioxide : 

 Mean of out-door air, 4. per 10,000/ 



3 p. m., lecture hall, 9.086 per 10,000, one-half hour before lecture. 

 4.15 p. m., lecture hall, 12.505 per 10,000, three-quarters of an hour after beginning lecture. 



Persons present declared the air to be more oppressive than on March 

 1, but the figures show no material difference.* The highest essential 

 impurity (as measured by carbon dioxide) appeared on March 6, when 

 there was no lecture, and it is probable that if there had been a lecture 

 on that day the highest figures for contamination by respiration would 

 then have appeared. 



Summarizing the several observations, they result as follows : 



March 1. Temperature increased 4P F. during the lecture. 



March 1. Relative humidity increased 11 percent, during the lecture. 

 (Floors had been wet before lecture.) 



March 6. Temperature increased 4° during four hours in lecture hall. 



March 6. Eelative humidity increased 7 per cent, during four hours. 

 (No lecture.) 



March 8. Temperature increased 5° during lecture. 



March 8. Relative humidity increased 6 per cent, during lecture. 



March 1, CO2 exceeded outside air 3.53 per 10,000 before lecture. 



March 1, CO2 exceeded outside air 7.08 per 10,000 middle of lecture. 



March C, CO2 exceeded outside air 5.44 per 10,000 at 1 j). m. (No lect- 

 ure.) 



March 8, CO2 exceeded outside air 5.086 per 10,000 before lecture. 



March 8, CO2 exceeded outside air 8.505 per 10,000 near end of lecture. 



If this excess be all attributed to respiratory impurity, it has exceeded 

 " the maximum amount of respiratory impurity permissible in a prop- 

 erly ventilated sjiace" (Dr. Ohaumont), viz, 2 parts per 10,000, by — 



Parts per 10,000 before lecture March 1 1.53 



Parts per 10,000 half throuojh lecture March 1 5. 08 



Parts per 10,000 no lecture March 6 3. 44 



Parts per 10,000 before lecture March 8 3.086 



Parts per 10,000 three-fourths through lecture March 8 6. 505 



The increase due to respiratory impurity on the two lecture days of 

 experiment, while the lecture continued, was : 

 March 1 . In half an hour, 3.55 parts per 10,000. 

 March 8. In three-fourths of an hour, 3.419 parts per 10,000. 



* In the increase of COi during the lecture. 



