140 EXCRETION. 



Under violent and prolonged exercise, the loss of weight 

 by exhalation from the skin and lungs may become very con- 

 siderable. It is stated by Mr. Maclaren, the author of an ex- 

 cellent work on training, that in one hour's energetic fencing, 

 the loss by perspiration and respiration, taking the average 

 of six consecutive days, was about three pounds, or accurate- 

 ly, forty ounces, with a varying range of eight ounces. 1 



When the body is exposed to a very high temperature, 

 the amount of exhalation from the surface is immensely in- 

 creased ; and it is by this rapid evaporation that persons 

 have been able to endure for several minutes a temperature 

 considerably exceeding that of boiling water. Dr. South wood 

 Smith made some very interesting observations on this point 

 upon workmen employed about the furnaces of gas-works 

 and exposed to intense heat ; and he found that in an hour, 

 the loss of weight amounted to from two to four pounds, this 

 being chiefly by exhalation of watery vapor from the skin. 8 

 In these instances the loss of water by transpiration is sup- 

 plied constantly by the ingestion of large quantities of liquid. 



Properties and Composition of the Sweat. A very com- 

 plete and satisfactory analysis of the sweat was made by 

 Favre, in 1853. After taking every precaution to obtain the 

 secretion in a perfectly pure state, he collected a very large 

 quantity, nearly thirty pints (fourteen litres), the result of 

 six transpirations from one person, which he assumed to 

 represent about the average in composition. 3 The liquid was 



1 HACLAREN, Training, in Theory and Practice, London, 1866, p. 89. 



2 SOUTH-WOOD SMITH, Tlie Philosophy of Health, London, 1865, p. 284, et seq. 

 Dr. Smith found great differences in the loss on different days in the same per- 

 sons, and a great variation in the different persons employed in his experiments. 

 In his third series of experiments, made upon ten workmen, the minimum of 

 loss in one hour was two pounds. The maximum was in two persons " who 

 worked in a very hot place for one hour and ten minutes." One of these lost 

 four pounds and fourteen ounces, and the other, five pounds and two ounces. 



* FAVRE, Recherches sur la composition chimique de la sueur chez Vhomme. 

 Archives generales de medecine, Paris, 1853, 5me serie, tome ii., p. 1, et seq. 



The analysis of the sweat by Favre is the one most frequently referred to by 



