OF THE SKIN CUTANEOUS TRANSPIRATION. 523 



he had collected ; whilst those of Schottiu 1 raise it as high as 22.4 parts per 

 1000, of which, however, 12 parts consisted of epithelium and insoluble 

 matters. 



421. The entire amount of fluid which is "insensibly" lost from the Cuta- 

 neous and Pulmonary surfaces was estimated by Seguin at 18 grains per 

 minute; of which 11 grains pass off by the skin, and 7 by the lungs. 

 Funke, 2 with two students, made numerous experiments upon the amount 

 and characters of the Sweat excreted from the hand and forearm under 

 different circumstances. In these experiments the arm was inclosed in a 

 caoutchouc bag, and each experiment lasted for one or two hours. It was 

 found that the largest quantity of sweat obtained from the forearm and 

 hand under favorable circumstances, in one hour, was 740 grains, which 

 would, in 24 hours, supposing the secretion to continue at the same rate, 

 amount to about 2J? Ibs. But, from accurate measurements, Funke ascer- 

 tained that the ratio of the superficies of the forearm and hand to that of 

 the body generally was as 1 : 17; so that if the perspiration took place con- 

 tinuously and at the same rate from the whole surface of the body, upwards 

 of 42 Ibs. might be discharged in 24 hours. On the other hand, the mini- 

 mum quantity excreted by the hand and forearm was 48 grains per hour, 

 which would amount to 1152 grains in 24 hours, and this, multiplied by 17, 

 would give 2| Ibs. for the amount eliminated from the whole body in 24 

 hours. It was found, however, that different regions of the body gave off, 

 in proportion to their surface, very different quantities of fluid : thus, in no 

 instance was the amount discharged by the leg equal to that given off by the 

 arm. Moreover, the three experimenters furnished very different propor- 

 tions of sweat under the same circumstances: thus, with active exercise in the 

 sun, the proportion between them was as 1 : 2.3 : 4.4, and in another experi- 

 ment as 1 : 1.7 : 2.06. Funke draws the conclusion from his experiments, 

 that the entire amount of. perspiration from the whole body may fluctuate 

 from about 2 ounces (819 grains) to about 29 ounces (12,588 grains) per 

 hour, the quantity of solid residue varying from 14.25 to 107.57 grains per 

 hour. Favre,by taking large quantities of warm drinks, and exposing the body 

 to a high temperature, collected no less than 2560 grammes, or above 5s Ibs. 

 of water in 1 J hours. It is difficult to give an average for the 24 hours when 

 the variations are so great ; but it may, perhaps, be estimated at about 2 Ibs., 

 the exhalation of aqueous vapor by the lungs being rather less than 1 Ib. 

 ( 318). An interesting series of observations has recently been published 

 by Dr. Victor Weyrich :i upon the relative amounts of insensible perspira- 

 tion under different conditions. The instrument he employed was a modi- 

 fication of Daniell's hygrometer; and his experiments extended over more 

 than a year. He found that variations of temperature between 55 and 70 

 F., when the body was clothed, produced little effect; but every 1 C. 

 (= 14- F.) above 70 F. occasioned an increase of 2 per cent, in the total 

 amount of vapor exhaled, and for every 1 C. below 55 F. there was a 

 diminution of from 1 to H per cent. He observed that the effects of the 

 relative moisture of the air were in great measure concealed by variations 

 in temperature, so that the highest averages of insensible perspiration occur- 



1 Archiv fur Physiol. Heilkunde, Bel. ii, pp. 73-104. 



2 Beitnige zur Kenntniss dt-r Schweiss Secretion; Moleschott's Untersuchungen 

 zur Naturlehre, u. s. w.. iv, p. 36. 



3 Die unmerkliehe Wasserverdunstung der Menschliohen Haut, Leipzig, 1862. 

 See abstract in Med.-Chir. Rev., 1863, vol. ii, p. 359. See also Rohrig, Die Phys- 

 iologic der Hautathmung, Deutsche Klinik, 1872, No. 23; and ErUrminn, Zur 

 Physiologic der Wasserverdunstung von der Haul, in Zeitschrift f. Biologic, Bd. xi, 

 pp. 1-78,' 1875. 



