ix THE SKIN AND CUTANEOUS GLANDS 491 



the composition of the sweat in a patient suffering from rheumatism, 

 who was made to sweat 1-2 hours in a bath : 



Specific gravity .... 1003-1006 



Water 99'09-99'16 per cent, 



Solids 0-91- 0-85 



Organic substances . . . 0'42- 0'85 



Inorganic substances . . . 0'67- 0'65 



Sodium chloride .... 0'52 



Earthy phosphates . . 0'03 



Sulphuric acid . . . 005 



Potassium 0'04 



Urea 012 



This table does not include either the lactic acid or the 

 sudoric or hidrotic acid (a nitrogenous acid with the empirical 

 formula C 10 H 16 N 2 O 13 ) of Favre, which were not found by any 

 other observers. 



The chlorides, and still more the phosphates and sulphates 

 of sweat, are less abundant than those of urine, as shown by 

 Kast (1887). 



There is now no doubt as to the presence of urea in normal 

 sweat. The different amounts found by different observers may 

 partly depend on the dissimilar interval between the secretion 

 and its analysis, in which a certain variable proportion of the 

 urea undergoes conversion by ammoniacal fermentation. 



According to Argutinsky's experiments on himself, by the 

 vapour-bath, as to the total nitrogen eliminated from the skin, 

 68 '5- 74-9 per cent is present in the sweat in the form of urea, 

 and 31-5-25'! per cent in the form of ammonia. The same 

 observer estimated the amount of nitrogen eliminated in the 

 sweat during severe walking or climbing exercise. With this 

 object he wore a special suit of cotton clothes, which were 

 extracted, when saturated with sweat, at the end of the excursion, 

 the extract being analysed by Kjeldahl's method. The following 

 were the results of three experiments : 



Excursion of about 20-22 kilos, in 7 hrs. (July). N excretion = 704 '4 mgrins. 

 18-20 partly climbing (Aug.) =753'5 



18-20 (Oct.) =219-3 



According to Argutinsky the nitrogen excreted by the skin 

 may amount to 4*7 per cent of that eliminated by the urine, which 

 should be taken into account in making exact calculations of the 

 total products of metabolism. 



Besides urea and ammonia, other urinary constituents have 

 been found in human sweat. Capranica detected creatinine 

 in the proportion of '04 per cent. In uraemic conditions the 

 cutaneous excretion of these products may be enormously increased. 

 Schottin and others found urea crystals in the skin of uraemics. 



The small quantity of fatty acids which causes the character- 



