SWEAT. 



843 



nitrogen when an animal diet had been 

 used, while carbonic acid prevailed when vege- 

 table food was taken. This experimenter also 

 satisfied himself that carbonic acid was evolved 

 from the skin in a gaseous form, and need not 

 be the result of oxydation of carbon by con- 

 tact with air, as he was able to collect it over 

 water from the skin. The insensible cuta- 

 neous transpiration may be regarded then 

 as composed of aqueous vapour, carbonic 

 acid, and nitrogen gases ; the two latter not 

 only vary- in 2 in proportion like the first, but 

 probably being sometimes absent, even in 

 health, according to conditions of the organ- 

 ism, which are not yet sufficiently investi- 

 gated in relation to this subject. 



When, under the conditions referred to 

 at the commencement of this article, the sur- 

 face becomes covered with sweat, the various 

 matters passing away from the skin by exces- 

 sive secretion have been examined by che- 

 mists with the following results : 



The total solid matters passing away from 

 the unexcitcd skin have been calculated at 

 about 7 to 8 scruples in the 24- hours, but the 

 very nature of the inquiry prevents any great 

 reliance being placed in such results. 



When sweat is collected, as was clone by 

 Simon, from persons subjected to the vapour 

 bath, it appears as a turbid fluid, yielding a 

 deposit by standing This deposit consists of 

 epithelium scales. The clear fluid was found 

 by Simon to possess a specific gravity of 

 1003 to 1004-. This result, however, must be 

 modified continually by the water condensed 

 on the surface from the aqueous vapour of 

 the bath. The fluid was acid, but only very 

 slightly so, and in the course of twenty-four 

 hours it became neutral. The acidity of the 

 sweat was therefore dependent on the pre- 

 sence of carbonic acid. Ammonia was evolved 

 from it after exposure. Simon analysed his 

 own sweat. He found it to develop an odour 

 of ammonia, and could detect that gas by 

 testing with the vapour of hydrochloric acid. 

 On evaporation, the peculiar smell of animal 

 extractive mutter was observed. When the 

 dry matter was triturated with potash, ammo- 

 nia came off. Sulphuric acid added to ano- 

 ther portion developed sulphurous acid at 

 first, and afterwards produced a strong odour 

 of acetic acid. In one instance observed by 

 Simon, the sweat gave oft' the odour of 

 butyric acid so strongly as to leave no doubt 

 on bis mind of the presence of that substance. 

 From various experiments, Simon concludes 

 normal sweat to contain 



1 . Matters soluble in ether : traces of fat, 

 sometimes including butyric acid. 



2. Matters soluble in alcohol : alcoholic 

 extractive, free lactic or acetic acid, chloride 

 of sodium, lactates and acetates of potash and 

 soda, lactate or hydrochlorate of ammonia. 



3. Matter soluble in water : aqueous ex- 

 tractive, phosphate of soda, and, occasionally, 

 alkaline sulphate. 



4. Matters insoluble in water : desqua- 

 mated epithelium, phosphate of lime, and 

 peroxide of iron. 



Berzelius examined and analysed sweat as 

 obtained from the forehead. He found it to 

 contain much the same substances that exist 

 in the acid juice of flesh. He states chloride 

 of sodium to be in excess, however. The 

 skin is certainly an active excreter of free 

 phosphoric and lactic acids, and assists the 

 urine in its important office of discharging 

 these acids from the system. Landerer has 

 lately shown the presence of urea in healthy 

 sweat, and it is probably by decomposition of 

 this substance that collected sweat becomes 

 ammoniacal. Tims, the skin would appear, 

 under varying conditions, to assume the excre- 

 tory duties of the lungs and kidneys, and we 

 are almost constrained to regard its function 

 as supplementary as well as complimentary 

 to that of respiration aud the excretion of 

 urine. 



Anselmino has, perhaps, made the best 

 analyses of the sweat. According to him 

 one hundred parts of the solid matters of 

 sweat contain 



1. Substances insoluble in water and 



alcohol (chiefly calcareous salts) 2'0 



2. Aqueous extractive matter (re- 



garded as salivary matter by An- 

 selmino, according to Berzelius 

 without sufficient reason), and 

 sulphates - - - 21'0 



3. Spirituous extractive (chloride of 



sodium and osmazome) - - 48'0 



4. Alcoholic extractive (osmazome, 



lactic acid and its salts, regarded 

 by Anselmino as acetic acid and 

 acetates) - - 20 -0 



In order to obtain the solid matters of the 

 sweat, Anselmino collected it in the vapour 

 bath by means of clean sponges. The fluid 

 so obtained was filtered, and the water dis- 

 tilled off. Acetate of ammonia was found in 

 the receiver. Simon considers acetic acid to 

 be a constant constituent of the sweat, and 

 with Berzelius considers hydrochlorate of am- 

 monia to be a normal component of the fluid. 

 Simon, though agreeing in the general with 

 the results of Anselmino, failed to detect 

 sulphates in freshly collected sweat. He 

 found it, however, in the incinerated residue, 

 from which he infers that some of the con- 

 stituents of sweat contain sulphur. 



The following is Anselmino's analysis of 

 sweat in 1000 parts: 



Water - - 995'00 987'500 



Epidermis and calca- 

 reous salts - -10 -250 

 Aqueous extractive 



matter (sulphates) 1-05 2'625 



Spirituous extractive, 

 chlorides of sodium 

 and potassium - 2'40 G'OOO 

 Alcoholic extractive, 

 acetatcs,lactatcs,and 

 free acetic acid 1 '45 3'625 



In the ash of the dried residue of sweat, 

 Anselmino found carbonate, sulphate, and 

 phosphate of soda, chloride of sodium, phos- 

 phate and carbonate of lime, with traces of 

 iron. In every 100 parts of dry matter of 



