212 UNORGANISED FLUIDS. 



four hours seven or eight scruples ; the remainder being 

 merely water, retaining in it carbonic acid and nitrogen, the 

 quantity of the former gas being increased by vegetable 

 diet, and the amount of the latter by an animal regimen. 

 Simon has established the existence, in normal sweat, of 



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

 including butyric acid. 



2. Substances soluble in alcohol: alcohol extract, free 

 lactic or acetic acid, chloride of sodium, lactates, and acetates 

 of potash 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, 

 phosphate of lime with a little peroxide of iron. 



The quantity of fluid exhaled is subject to very great 

 variations ; thus it is increased by a dry and light atmosphere, 

 while it is diminished by a damp and dense condition of the 

 air. It is at its minimum at and immediately after meals, 

 while it is at its maximum during the actual period of 

 digestion. The cutaneous perspiration is in antagonism with 

 the urinary secretion ; thus an excessive secretion of urine 

 diminishes that of the skin, and a diminution of the activity 

 of the kidneys is usually followed by an augmentation of 

 that of the sudoriparous glands. 



But little of interest, in a microscopic point of view, 

 attaches to this fluid; the only solid organic constituent 

 contained in it being detached scales of epidermis, which 

 is ever undergoing a process of destruction and renewal; 

 these scales, therefore, do not form part of the sweat, but 

 become mixed up with it in a secondary manner. 



The copious formation and discharge of the cutaneous 

 fluid which occur under certain circumstances, thus do not 

 merely afford a relief to internal organs, but serve also, by 

 detaching and washing away the older and useless cells, to 

 cleanse the epidermis, and to render this more efficient as an 

 evaporating surface. 



The crystals formed on the evaporation of the sweat, in 



