602 report— 1878. 



TUESDAY, AUGUST 20, 1878. 



The following Papers were read: — 



1. On the Excretion of Nitrogen. Part II. — By the Skin. 

 By J. Byrne Power. 



I have already published a paper upon the renal excretion of nitrogen. Since 

 then I have made some experiments on the cutaneous excretion of nitrogen, the 

 results of which, and the modus operandi, I beg to lay before this Association for 

 the first time. I may mention that I was induced to undertake these as well as 

 my former researches with a view to the study of the physiological action of the 

 hot-air bath, which I have found personally beneficial, in the hopes of establishing 

 its utility on a scientific basis. In considering the action of prolonged sweating 

 the question most practically important is, can the skin be made to act vicariously 

 of the other organs of excretion, and, if so, to what extent ? I believe that the 

 generally received opinion is that the skin can be made so to act ; and how far such 

 opinion is warranted by experiment I hope in this paper to show more clearly than 

 has hitherto been done. At present I confine myself to the cutaneous excretion of 

 nitrogen, an element the excretion or retention of which in the system is a ques- 

 tion of supreme importance, physiologically and pathologically. Without here 

 attempting to quote the numerous authorities, I may shortly state what I consider 

 to be the present position of this important question. Funke, by the results of his 

 experiments upon himself and his two pupils published in 1853, not only verified 

 those of Anselmino, Berzelius, Favre, and others as to the existence of nitrogen in 

 the sweat, but proved its existence as urea, and was the only person, as I believe, 

 who ever succeeded in making an estimation of the total quantity of nitrogen ex- 

 creted by the skin in a given time until I attempted it myself. On the other hand, 

 many experimenters — Voit, Ranke, Parkes, and others — have denied the existence 

 of nitrogen in the sweat. They arrive at this conclusion inferentially, finding that 

 the amount of nitrogen excreted by the kidneys and bowels was equal, and in some 

 cases even exceeded, the quantity ingested, therefore leaving no room for any 

 excretion by the skin. The most recent English authority on the point — the late 

 eminent Professor Parkes, in the Croonian Lectures delivered by him before the 

 College of Physicians in London, in 1871 — after reviewing most of the authorities, 

 thus concludes : — " Ou the whole, there appears to be little doubt that, apart from 

 detached skin structures, the balance of evidence is against the passage of nitro- 

 genous substances by the human skin." I do not think that the form of negative 

 proof advanced by these authorities can stand before the positive results of those 

 who obtain nitrogen in some form or other as a constituent of the fluid portion of 

 the sweat. With regard to Funke, I consider that his estimation of the excretion 

 of nitrogen per diem — amoimting to as much as from 4 - 76 to 7 - 045 grammes — 

 is excessive. He arrives at these results by multiplying the quantity obtained in an 

 hour by 24, necessarily assuming the constancy of the sweat secretion, which 

 assumption is contradictory to the statement made in another part of his paper, to 

 the effect that " in one or two hours the quantity of the supply begins to diminish, 

 even though the temperature and movements remain unaltered, and falls to such a 

 minimum that one can scarcely perceive the increase even during greater intervals 

 of time." Funke obtained the sweat from the arm only, and, having ascertained 

 by measurement a ratio between its superficies and that of the whole body, he thus 

 estimated the entire cutaneous excretion. His experiments were made under con- 

 ditions of more or less violent exercise. I made mine on the body in a state of 

 rest in the hot-air bath, considering results thus obtained more referable to con- 

 ditions of disease. I shall now, without dwelling on my many failures, briefly 

 state the mode of collecting the excretion which I finally adopted as being the 



