688 
PROFESSOR HARLEY ON THE INFLUENCE OF 
After a certain quantity of blood (usually 62 cubic centimetres) or other fluid was 
introduced at the mouth (b), the latter was firmly closed with a tightly fitting cork, and 
the remaining opening (f) secured by a ligature, so that all communication between 
the external atmosphere and the gas confined with the blood was effectually interrupted. 
When the experiment was completed, the gas was obtained from the receiver by 
plunging the lower end of the vessel into mercury, and carefully removing the cork, 
while it was still retained in that position, so that neither the contained gas could find 
an exit, nor the external air obtain admittance. A tube (B) partly filled with mercury 
was now carefully adjusted to the mouth of the receiver by a well-fitting cork ( d ); the 
receiver was next removed from the mercury trough, and a fine capillary glass tube (C) 
inserted into the free end of its piece of caoutchouc tubing ; the end of this tube was 
dipped under the surface of mercury and the ligature at f removed. The mercury in 
B immediately descended and forced the atmospheric air out of the tube C, which in 
its turn became filled with gas from the receiver. The end of the tube C was then 
brought under an inverted eudiometer filled with mercury, and more of that liquid 
poured into B until sufficient gas was obtained from the receiver for analysis. In the 
fourth place, the temperature of the human body was imitated by employing an artificial 
digesting apparatus which could be readily kept at a constant heat of 38° C. 
Lastly, the experiments were performed in a gas-laboratory, the temperature of which 
varied but slightly during the twenty-four hours, and their performance was thereby 
greatly facilitated. For the use of this laboratory I am deeply indebted to the President 
and Council of University College, London, who most liberally placed it at my entire 
disposal during a period of three years. 
As indicated by the title of the paper, the series of researches about to be detailed is 
devoted to the influence of some physical and chemical agents on the blood with refe- 
rence to its action on the respiratory gases. For the sake of convenience, the communi- 
cation is divided into two parts. 
The first includes the influence of the following physical agents. 
a. The effect of simple diffusion in producing a change in the mixture of gases con- 
fined with blood. 
b. The influence of motion on the changes reciprocally exerted upon each other by 
blood and atmospheric air. 
c. The influence of time on the interchange of the respiratory gases. 
d. The effect of temperature on the same, from 0° C. to 38° C. 
e. The influence of the age of the blood, including the effect of the putrefaction. 
The second part of the communication is devoted to the consideration of the influence 
of chemical agents, especially such as are usually denominated powerful poisons. These 
agents are selected from the three kingdoms. 
a. Animal. 
b. Vegetable, and 
c. Mineral. 
