58 Dr. Marcet. .A bsorption of Oxygen and [June 4, 



quadrants. And this expression, although containing only three 

 constants, fitted with considerable accuracy all the curves given in 

 the several sheets accompanying the paper. 



The results of the investigation, briefly summed up, are as 

 follows : 



1. The quadrant electrometer as made by Messrs. "White, although 

 it may be carefully adjusted for symmetry, does not usually even 

 approximately obey the recognised law for a quadrant electrometer 

 when the potential of the needle is altered. 



2. The peculiarities in the behaviour of the White electrometer are 

 due mainly to the electrical action between the guard tube and the 

 needle, and to the slight tilting of the needle that occurs at high 

 potentials. 



3. By special adjustments of the quadrants of the White electro- 

 meter the sensibility can be made to be either nearly independent 

 of the potential of the needle, or to be directly proportional to the 

 potential, or to increase more rapidly than the potential of the needle. 



4. By altering the construction of the instrument as described, the 

 conventional law for the quadrant electrometer is obtained without 

 any special adjustment of the quadrants beyond that for symmetry, 

 and the instrument is rendered many times as sensitive as the 

 specimen we possess of the White pattern. 



V. "Researches on the Absorption of Oxygen and Formation 

 of Carbonic Acid in ordinary Human Respiration, and in 

 the Respiration of Air containing an Excess of Carbonic 

 Acid." By WILLIAM MARCET, M.D., F.R.S. Received 

 May 25, 1891. 



Allow me to begin by recording the valuable help I have expe- 

 rienced throughout the present enquiry from my assistant, Mr. Ed- 

 ward Russell, F.C.S. We have both put our shoulders to the wheel, 

 and have gone together through the great number of calculations 

 the work entailed. I am much indebted to Mr. Russell for the pains 

 be has taken, and the accuracy of his judgment whenever a knotty 

 point had to be met and overcome. 



My object in the following paper is to give an account of the con- 

 sumption of oxygen in human respiration, or, in other words, to 

 determine the proportions of oxygen transformed into carbonic acid, 

 and of oxygen retained in the blood, to which is added a short in- 

 quiry into the effects produced by the inhalation of air containing 

 C0 2 on the interchange of the pulmonary gases. The investigation 

 was carried out, so far, on myself and Mr, Russell, while under the 



