522 OF SECRETION AND EXCRETION. 



the form either of sensible or of insensible transpiration ; the latter being 

 constant, the former occasional. When collected in the fluid state, sweat is 

 a colorless liquid, possessing a peculiar odor according to the part of the 

 skin from which it is obtained, and more or less turbid from the presence of 

 sebaceous matter and epidermal scales, which constitute from 0.2 to 0.3 per 

 cent, of the whole amount of the excretion. Its reaction is usually acid, 

 though Gillibert 1 and Favre found that after protracted sweating it became 

 neutral or even alkaline. Its acidity appears to be due to the presence of 

 certain volatile acids, as the acetic, butyric, and formic ; to which, and pos- 

 sibly to the metacetonic and capric acids, we are probably to attribute the 

 sour smell which it possesses in some disordered states of the system. The 

 substances which have been found to be constant constituents of the sweat 

 are, water, fat, various volatile fatty acids in addition to those already men- 

 tioned, urea and inorganic salts, amongst the chief of which are the chlorides 

 of sodium and potassium, the alkaline phosphates and sulphates, the earthy 

 phosphates, and iron. That it is a true secretion, and not a mere transu- 

 date, is shown by the entire absence of albumen, except under very unusual 

 conditions, and then only occasionally. 2 Other constituents of the sweat, 

 whose presence is not constant, or the nature of which has not been satisfac- 

 torily determined, are, the salts of ammonia, of lactic acid, and of the hy- 

 drotic acid of Favre, and certain pigmentary substances of various shades. 

 In disease, uric acid, grape-sugar, albumen, and biliary coloring matters, 

 have been found ; and when taken with the food, benzoic acid (partly con- 

 verted into hippuric), succinic, cinuamic, and tartaric acids, arsenious and 

 arsenic acids, with iodine and iodide of potassium, have been recovered in the 

 sweat. Fuuke calculates that about 11 grains of nitrogen are daily elimi- 

 nated by the skin through the desquamatiou of the epithelial scales. He 

 also found urea (as was first stated by Dr. Lauderer 3 ) to be a constant con- 

 stituent. In one experiment, the entire quantity of perspiration for the 

 whole body for 1 hour being 3320 grains, 6J grains were found to be present. 

 If the secretion had continued at the same rate for 24 hours, 157 J grains of 

 urea would have been eliminated, containing 73 J grains of nitrogen. Under 

 ordinary circumstances, however, it is probable that a very much smaller 

 quantity is thus eliminated. From the general uniformity in the proportion 

 of solids to 100 parts of sweat, observed by Fuuke, it is obvious that, with 

 an increase in the quantity of fluid excreted by the skin, there is also an 

 augmented excretion of solids; and to the deficiency which is thus produced 

 in the salts of the blood may be partly assigned the debilitating effects of 

 profuse perspirations. Other causes, however, probably concur in producing 

 those effects. Thus the great fatigue which is experienced as a consequence 

 of muscular exertion in a heated atmosphere, may fairly be set down to the 

 diminished activity of the respiratory process at high temperatures ( 311, i), 

 and the colliquative sweating of hectic fever is obviously not a cause but a 

 consequence of, though it may also react upon and increase, the debilitated 

 state of the general system. The proprotion of solid matter contained in 

 different specimens differs very greatly ; thus, according to Anselmino, it 

 varies between 5 and 12.5 parts in 1000; the observations of Favre'* give 

 4.43 parts per 1000 as the proportion contained in nearly nine gallons which 



1 Gillibert d'Hercourt, Gaz Med. de Lyon, Mai, 1853, Rev. Mod., 1850. 



2 See Loube, Virchow's Archiv, Bd. xlviii, pp. 181,31)1; and Archiv f. Klin. Med., 

 Bd. vii, p. 1. 



3 HelWs Archiv, I3d. iv, p. 196. See also Deiningor, Deutsch. Archiv f. Klin. 

 Med , 1870, lid. vii, p. 587. 



4 Archives Goner, do Med., 1853, 5me Sor., torn, ii, pp. 1-12. 



