94 DR. R. ANGUS SMITH PHYSIOLOGICAL EFFECTS OF 



found in the air of some mines, and an amount of car- 

 bonic acid actually less, such extraordinary changes should 

 result in the functions of a healthy man. We want no 

 other experiment than this to prove great evil arising 

 from impure air, either in mines or elsewhere. 



In order to obtain similar results in a shorter time, five 

 persons entered the lead chamber, expecting to have in one 

 hour the same results that were obtained by one person in 

 five hours. The figures are here given ; it is seen that they 

 are not exactly the same as previously. Time causes us to 

 yield, although we may struggle against the evil influences 

 for an hour or so. The efiects are not exactly such as were 

 expected. The pulse begins to be irregular very soon, and 

 certainly when the air contains 0*4 per cent, of carbonic 

 acid, in three cases 0*2. It rises and falls, but at last 

 begins to fall. In all cases, however, it becomes very weak, 

 as in the first experiment. 



With the younger it rose rapidly at first, and seems to 

 indicate the more rapid struggle for life with the more 

 advanced ; it was a steady determination not to be changed 

 by external circumstances, although they gradually caused 

 a change at last. 



These figures will probably induce many others to con- 

 tinue the inquiry. 



May it not be useful to lower the pulse in this method 

 in some cases? If so, must the experiment be tried with 

 pure carbonic acid ? And how much was due to the car- 

 bonic acid, and how much to organic matter? All these 

 are interesting questions. Meantime the question is so 

 far answered, that we see the eff'ects due to the want of 

 ventilation. 



