Du. Buchanan on the Effects of the Inhalation of Ether. 159 



most extraordinary part <»f the whole phenomena, and the most difficult to 

 explain. Daring the inhalation, which is usually continued from five to 

 seven minutes, blood, highly charged with ether, is applied to the heart 

 ami brain; while the blood, circulating in the lower parts of the body, 

 contains a much smaller proportion of it. Now, on stopping the inhala- 

 tion, the blood, circulating in the heart and brain, speedily passes off by 

 tin* v<ius, ami is succeeded by the comparatively pure blood coming from 

 the lower regions of the body; and so the narcotic symptoms disappear. 



It is far otherwise, when alcohol is absorbed from the stomach, for the 

 whole mass of blood must be impregnated with it, before a highly charged 

 blood can be applied to the heart and brain ; and then, the effect continues 

 for many hours till the alcohol has been thrown out of the system by the 

 skin and lungs. 



It must not be supposed, with respect to the ether, that, on the 

 subsidence of the narcotism, it disappears from the body; for it is 

 merely weakened in its effects, by being diffused equably over the whole 

 mass of blood*, but, that it remains within the body is obvious from the 

 smell of the breath for many hours afterwards, and from its frequently 

 causing copious, perspiration. 



The small quantity of ether, necessary to produce narcotism when 

 inhaled, depends on the principle above stated, that the ether is applied 

 directly and continuously to the tissues of the heart and brain. It is 

 difficult to determine the actual dose of the ether, or the quantity of 

 it absorbed into the blood. The first step is to determine what quantity 

 of it is inhaled into the lungs; and this inquiry is the more important as 

 there is a necessary connection between the quantities of air and of ethereal 

 vapour which are simultaneously inhaled, and by determining the one we 

 determine also the other. Now, if at any given temperature, the chamber 

 of the inhaler be saturated with vapour, since there is a free communica- 

 tion between the chamber and the external air, it is obvious that the 

 tension of the ethereal vapour, added to that of the air within the chamber, 

 must just balance the pressure of the external atmosphere. We know 

 the tension of the vapour of ether at all ordinary temperatures from 

 the experiments of Dalton. Supposing, therefore, the barometer to be at 

 30 inches, we have only to ascertain from Dalton's table the height of the 

 column of mercury indicating the maximum tension of the vapour at any 

 given temperature, and also the difference between that column and one of 

 30 inches high, and we then have two numbers which express the relative 

 volumes of ethereal vapour and air existing in the chamber of the inhaler. 

 Thus, at tin temperature of C4°, the maximum tension of ethereal vapour 

 -ponds to a column of mercury 15 inches high, and the difference 

 ii that column and one of 30 inches is also 15 inches, so that equal 

 volumes of ethereal vapour and of air are contained in the chamber of the 

 inhaler. At the temperature of 96°, again, the tension of the vapour is 

 equal to that of the atmosphere, or to a column of mercury 30 inches 

 high, so that the whole air it? expelled from the chamber, which is entirely 



