CH. xxxvin.] THE SWEAT. 579 



Water . 98-88 per cent. 



Solids . . ri2 



Salts . . 0-57 



NaCl . . 0-22 to 0-33 



Other salts . o'i8 (alkaline sulphates, phosphates, 



lactates, and potassium chlo- 

 ride) 



Fats . . o - 4i (including fatty acids and iso- 



cholesterin) 



Epithelium. o'i7 



Urea . . cro8 



The salts are in kind and relative quantity very like those of 

 the urine. Funke was unable to find any urea, but most other 

 observers agree on the presence of a minute quantity. It appears 

 to become quickly transformed into ammonium carbonate. The 

 proteid which is present, is probably derived from the epithelial 

 cells of the epidermis, sweat-glands, and sebaceous glands, which 

 are suspended in the excretion ; but in the horse there is albumin 

 actually in solution in the sweat. 



Abnormal, Unusual, or Pathological Conditions of the 

 Sweat. Drugs. Certain drugs (sudorifics) favour sweating, 

 e.g. pilocarpine, Calabar bean, strychnine, picrotoxine, muscarine, 

 nicotine, camphor, ammonia. Others diminish the secretion, 

 e.g. atropine and morphine in large doses. 



Large quantities of water, by raising the blood-pressure, 

 increase the perspiration. 



Some substances introduced into the body reappear in the 

 sweat, e.g. benzoic, tartaric, and succinic acids readily, quinine 

 and iodine with more difficulty. Compounds of arsenic and 

 mercury behave similarly. 



Diseases. Cystin has been found in some cases of cystinuria ; 

 dextrose in diabetic patients ; bile-pigment in those with jaundice 

 (as evidenced by the staining of the clothes) ; indigo in a peculiar 

 condition known as chromidrosis ; blood or hiumatin deriva- 

 tives in red sweat ; albumin in the sweat of acute rheumatism, 

 which is often very acid ; urates and calcium oxalate iu gout ; 

 lactic acid in puerperal fever, and occasionally in rickets and 

 scrofula. 



Kidney Diseases. The relation of the secretion of the skin to that 

 of the kidneys is a very close one. Thus copious secretions of urine, 

 or watery evacuations from the alimentary canal, coincide with dry- 

 ness of the skin ; abundant perspiration and scanty urine generally 

 go together. In the condition known as uraemia (see p. 552), when 

 the kidneys secrete little or no urine, the percentage of urea rises 

 in the sweat : the sputum and the saliva also contain urea under 

 those circumstances. The clear indication for the physician in 



p r 2 



