CHEMICAL NATURE OF SKIN SECRETIONS. 



671 



the breaking out of sweat, the excretion of carbon dioxide by the skin 

 is also suddenly increased, a fact probably related to the increased 

 activity of the gland-cells : 



E.ccretion of Water and Carbon Dioxide by the Skin at various Temperatures 



of Surrounding Air. 

 (Separate experiments on same individual, naked, in a Pettenkofer and A r oit's chamber). 1 



The sweat of man is a colourless, opalescent liquid of salt taste, 

 poorest in solids of all the secretions, though richest in salts in relation 

 to organic solids. 



Sweat is acid in reaction, even when collected from the palm of the 

 hand, where there is no danger of admixture of sebaceous secretion. 2 

 This acidity is probably due to volatile fatty acids, which may be 

 subsequently driven off, leaving an alkaline reaction at the surface of 

 the skin. 8 In profuse sweating the acidity may give way to neutrality, 

 followed later by alkalinity. 4 



NOTE TO TABLE. The sudoric or hidrotic acid of Favre has not been found by any 

 .subsequent observers. He gives the empirical formula, C 10 H 16 H 2 13 . Lactic acid also 

 has not been found by any other observer. 5 



1 Schierbeck, loc. cit. 



2 Fraii9ois-Franck, "Diet, encycl. d. sc. med.," Paris, 1884, Ser. 3, tome xiii. p. 51, 

 Art. "Sueur." 



3 Tourton, "These de Lyon," 1879, No. 24, Ser. 1. 



4 Favre, loc. cit. ; Trumpy and Luchsinger, Arch. f. d. gcs. Physiol., Bonn, 1878, 

 Bd. xviii. S. 494. 



5 For analysis of sweat of a rheumatic patient, see Harnack, Fortschr. d. Med., Berlin, 1893, 

 S. 91 ; also Hermann, Jahresb. il. d. Fortschr. d. Anat. u. Physiol.. Leipzig, 1895. Bd. ii. 

 S. 226. 



