842 



SWEAT. 



indeed, been termed " Sanctorian" in honour 

 of him. 



This subject, curiously enough, received 

 some attention from the merry monarch 

 Charles the Second, who instituted many ex- 

 periments on the subject. Among other less 

 exalted, but probably more trustworthy ob- 

 servers, may be mentioned Dodart, Keil, Ro- 

 binson, Home, and Linings, and of later date 

 Lavoisier and Seguin. According to an ex- 

 periment of Home, the perspiration during the 

 twelve hours of night varies from 12 to 18 oz., 

 and in 23 hours the discharge amounted to 3 

 Ibs. 3 oz. On another occasion, however, the 

 amount was only 2 Ibs. 6^ oz. Keil states the 

 medium quantity of perspiration to be 31 oz. 

 only. Robinson states the amount for summer 

 to be 27 oz., and in winter 30 oz. daily. 

 Hartmann, in Germany, makes the daily 

 amount of perspiration 45 to 46 oz. Dodart, 

 in France, gives 40 oz. 3 dr. 26 gr. for summer, 

 and 26 oz. 46 gr. for winter. Sanctorius found 

 that in the warm humid air of Venice, having 

 taken 8 Ibs. of ingesta, the perspiration in 

 the 24 hours amounted to 5 Ibs., the faeces 

 to 4 oz., and the urine to 69 oz. 



The observations made by Linings, in the 

 climate of South Carolina, bear importantly 

 on this subject. He found that while perspir- 

 ation, as might be expected, was most abund- 

 ant in the warm weather of summer, the 

 urine diminished proportionally, and that the 

 converse pertained for the winter. He ob- 

 served the perspiration to exceed the urine 

 during seven months, and the urine the pers- 

 piration during five months of the twelve. 

 The largest proportion of urine observed was 

 143 oz., which occurred in December. The 

 largest proportion of perspiration was 130 oz., 

 and was observed in September. The ingesta 

 were to the perspiration as 2'18 to 1. The 

 perspiration of the whole year was to the urine 

 as 1 to 1*08. These experiments differ from 

 those of Sanctorius and Rye, in showing that 

 the urine exceeds the perspiration even in a 

 hot climate. 



On reviewing all that has been done by 

 various experimenters, it appears doubtful 

 whether, even in warm climates, the cutaneous 

 exhalation exceeds that of the urine, and we 

 ought most probably to regard it as consider- 

 ably below the quantity stated by Sancto- 

 rius. It must be remembered that, as in 

 the experiments described above, the per- 

 spiration is estimated from the loss sustained 

 by the body during a given period, alter 

 subtracting the weight of fa?ces and urine 

 discharged ; we have the pulmonary exhalation 

 therefore included in the account, as well as 

 the cutaneous. 



Mr. Cruikshank made experiments which 

 are free from this source of error. He placed 

 his hand in a glass jar, making it air-tight by 

 means of bladder fixed round his wrist and 

 also bound tight to the mouth of the jar. He 

 assumed that his hand presented a surface 

 \yth that of the whole surface of the body, 

 and from that datum arrived at the conclusion 

 that the exhalation from the skin was 7 Ibs. 



6 oz. in the 24 hours, which, under exercise, 

 would amount to 12 Ibs. 



Mr. Abernethy made an experiment very 

 similar to the above, but according to his cal- 

 culation, the exhalation for 24 hours would 

 amount only to 2 Ibs. This extraordinary 

 difference may perhaps be accounted for by 

 the fact that Mr. Abernethy continued his 

 experiment six hours, and Mr. Cruikshank 

 only one hour, and such being the case, the 

 exhalation may have nearly ceased some length 

 of time before six hours had elapsed, owing 

 to the extremely moist atmosphere in which 

 Mr. A.'s hand was placed. Cruikshank, it 

 will be seen, would have to multiply by 24, 

 and Abernethy by 4 only for the result tf 24 

 hours. Thus the former would magnify the 

 excess (obtained by the first hour affording a 

 dryer atmosphere) into an important quan- 

 tity. 



Lavoisier and Seguin have made excellent 

 experiments with a view of ascertaining the 

 amount of cutaneous exhalation. They en- 

 closed the whole body in a varnished silk 

 bag. There was a small opening to this, which 

 was carefully cemented around the mouth of 

 the subject of experiment. Thus all the mois- 

 ture from the lungs escaped, while the cuta- 

 neous exhalation was confined in the bag. 

 By weighing the body before and after leaving 

 the bag, the total loss from skin and lungs 

 was ascertained. The amount of loss by the 

 lungs was ascertained by weighing the person 

 before he got into the bag and immediately 

 before he left it. After a long series of ex- 

 periments conducted in this manner, Lavoi- 

 sier and Seguin found that the mean loss by 

 pulmonary and cutaneous exhalation amounted 

 to 18 grs. per minute, or 2 Ibs. 13 oz. in 24 

 hours. Of this the pulmonary discharge was 

 15 oz., and the cutaneous exhalation 1 Ib. 

 14oz. This they regard, then, as the mean 

 amount of daily perspiration. The greatest 

 quantity of matter perspired in a minute, was 

 26'25 grs. troy, and the minimum 9 grs. Ex- 

 halation is increased by fluids, but not by solid 

 food. It is at its minimum during meals, and 

 at its maximum during digestion. 



Under certain conditions vapour has been 

 observed to escape from the body in very 

 great quantity. Thus, Haller observed, when 

 in the subterraneous caverns of Clausthal and 

 Rammelsberg, that a distinct cloud or smoke 

 could be perceived rising from the naked 

 human figure. 



Some diversity of opinion has prevailed 

 among experimenters as to the gases which 

 pass off from the body in company with the 

 water, by the function of insensible perspira- 

 tion., Abernethy and Mackensie detected 

 carbonic acid, and Collard de Martigny found 

 nitrogen in addition. These gases appear in 

 variable quantity, and are sometimes alto- 

 gether absent. After muscular exertion, and 

 after meals, they appear in great abundance. 

 According to Trousset, Barruel, and Ingen- 

 houss, nitrogen is sometimes exhaled without 

 carbonic acid. Monsieur Collard found that 

 the cutaneous transpiration contained most 



