SWEAT. 103 



If a portion of the residue is incinerated, the ash effervesces on 

 the addition of hydrochloric acid. On dissolving out the 

 chlorides with alcohol, and adding bichloride of platinum, we 

 obtain a slight yellow precipitate. The residue is soluble in 

 water, with the exception of some gray flocculi, and on the ad- 

 dition of tannic acid this aqueous solution yields a precipitate, 

 which shows that the sweat contains water-extract. The solu- 

 tion also contains a small quantity of lime, but hardly a trace 

 of phosphoric acid, and only once, in several trials, was there a 

 faint indication of sulphuric acid. When the whole residue of 

 the sweat was incinerated, the amount of phosphate of lime was 

 much larger, and a considerable quantity of sulphuric acid, as 

 well as traces of peroxide of iron, were always perceptible. 



It is true that these are superficial and merely qualitative in- 

 vestigations ; they are, however, sufficient to establish the ex- 

 istence, in normal sweat, of 



1. Substances soluble in ether: traces of fat, sometimes in- 

 cluding butyric acid. 



2. Substances soluble in alcohol : alcohol- extract, free lactic 

 or acetic acid,, chloride of sodium, lactates and acetates of pot- 

 ash and soda, lactate or hydrochlorate of ammonia. 



3. Substances soluble in water : water- extract, phosphate of 

 lime, and occasionally an alkaline sulphate. 



4. Substances insoluble in water : desquamated epithelium, 

 and (after the removal of the free lactic acid by alcohol) phos- 

 phate of lime, with a little peroxide of iron. 



The results of the investigations of other chemists coincide 

 generally with these conclusions of mine. Berzelius infers 

 from his analyses of sweat that collected in drops on the fore- 

 head, that it contains in solution the same substances which 

 occur in a dissolved condition in the acid fluid of muscu- 

 lar flesh, together with an excess of chloride of sodium. The 

 most comprehensive analyses of sweat have been made by Ansel- 

 mino. 1 He inclosed the naked arm in a glass cylinder, and 

 collected the sweat that had exhaled during several experiments : 

 in the course of five or six hours a table-spoonful had condensed. 

 A portion was heated with sulphuric acid, evaporated, and 



1 Tiedemann's Zeitschrift, vol. 2, p. 321. 



