20 GRAHAM I.rSK 



per hour in this first historical experiment on the hasal metabolism was 25 

 per cent too high. As for the experimental plan, it is as modern as the 

 work of to-day, and yet it was executed 140 years ago by the first man 

 who really understood the significance of oxygen. It is only in the last 

 decade that the summation of the individual stimuli caused by food and 

 muscular work and noted by Lavoisier has been verified. Lavoisier (/>) 

 also observed a constant relation between the quantity of oxygen consumed 

 and the rate of the pulse multiplied by the number of respirations. 



How Lavoisier achieved these remarkable results is not known, for 

 the times in which he lived became too troubled to allow further work in 

 pure science. We find, however, the following statement in the original 

 memoir: ."It would have been impossible to accomplish these exact 

 experiments upon respiration before the introduction of a simple, easy 

 and rapid method of gas analysis. This service M. Segiiin has rendered 

 to chemistry." 



If, now, one turns to the report of Seguin (Seguin (#), 1791 ) one finds 

 that he states that in his work with Lavoisier he used eudiometers 8 to 10 

 inches high and an inch in diameter in order to determine the "vital air" 

 or cxygen in the respired air. The tube was first filled with mercury and 

 inverted over mercury, a little of the gas to be analyzed was introduced 

 and then a bit of phosphorus, which phosphorus was later ignited by 

 bringing a burning ember in the vicinity of the glass, The rest of the 

 air to be analyzed was gradually admitted and when the tube cooled the 

 volume of the air remaining could be measured. The loss in volume 

 represented the quantity of oxygen absorbed. Carbonic acid could then be 

 absorbed by potash. Seguin stated that the older method, as originally 

 introduced by Priestley, had twenty sources of error but that his method 

 merited attention on account of the very great exactitude with which he 

 could determine the gases which are contained in respired air. 



He furthermore truly stated that "if we enter into a room containing a 

 large number of people we immediately smell a strong, suffocating odor, 

 but if we use eudiometers to analyze this foul air and compare it with 

 ordinary atmospheric air we find hardly any difference in the proportions 

 of ga?P3 which are contained in them." 



After Lavoisier's death Madame Lavoisier drew from memory the 

 apparatus used by her husband. The drawings were retouched by David, 

 Madame Lavoisier's instructor in art. There are two pictures quite dis- 

 similar. Good reproductions are to be found in Grimaux's "Lavoisier." 

 In both pictures Seguin sits naked in a chair, breathing through a mask 

 into a series of globes or bell jars. In both pictures Madame Lavoisier is 

 shown seated at a table, taking notes of the experiment. In botli pictures 

 the pulse is being counted. In one experiment a -weight is placed on 

 Seguin's instep. The arrangement of the apparatus is quite different in 

 the two pictures. In the experiment showing Seguin at work it seems as 



