PERSPIRATION. 279 



and excretes foreign matters, and is an organ of absorp- 

 tion. 



The watery secretion is sometimes termed perspirabile Sanctori* 

 anum m , after the patient and acute philosopher who first applied 

 himself professedly to investigate its importance. 



To ascertain the quantity of watery secretion, Lavoisier and 

 Seguin n enclosed the body in a silk bag varnished with elastic gum 

 and having a small opening carefully cemented around the mouth, 

 so that, by weighing the body previously and subsequently to the 

 experiment, they were able to ascertain exactly what had been 

 lost, and, by subtracting from this loss the weight of the perspired 

 contents of the bag, they also ascertained how much of this had 

 passed off by the lungs. From repeated trials they found the 

 mean pulmonary discharge in twenty-four hours amounted to 



lungs, independently, it would appear, of its chemical effect, as it is of use when 

 there is no circulation, when the heart is excised, either in frogs or cats, which 

 perish after this operation the sooner as the temperature is higher. When the 

 quantity of water, though limited, is sufficient to support life, the want of re- 

 spiration causes the frogs to become as slow in their motions as turtles, and dull 

 to all impressions on the senses (p. 65.)' Lizards, serpents, and turtles, also 

 carbonise the air by their surface ; but serpents and turtles, and, indeed, some 

 varieties of frogs, can live by respiration only, and this happens where the lungs 

 of the animal are proportionally large (p. 128.). The effect of air, however, 

 upon the surface, in reptiles at least, does not require the aid of circulation to 

 distribute its benefits ; for, when their heart is removed (and the same happens 

 with toads, salamanders, and cats), they live much longer in air than, in de-aerated 

 water (p. 3. sqq.) ; yet they live longer if the heart is not removed (p. 7. sqq.). 



m " Ars Sanctor. Sanctorii de Statica Medicina apkorismor. sectionibus vii. com- 

 prehensa. Venet. 1634. 16mo. 



C. de Milly and Lavoisier, Memoires de VAcad. des Sc. de Parts. 1777. 

 p. 221. sq. 360. sq. 



J. Ingen-Housz, Esepts. upon Vegetables. Lond. 1779. 8vo. p. 132. sqq. 



J. H. Voight. Versuch einer neuen Tkeorie des Feuers, p. 157. sq." 



" The balance employed by Sanctorius to estimate the loss of perspired matter 

 is described in his Comm. in primam Fen primi L. Canon. Avicennas. Venet. 

 1646. 4to. p. 781. 



Another, much simpler and better adapted for the purpose, is described by 

 Jo. Andr. Segner, De Libra, qua sui quisque corporis pondus explorare posset. 

 Getting. 1740. 4to. 



J. A. Klindworth, an excellent Gottingen instrument-maker and engineer, 

 altered this at my suggestion, and rendered it more convenient and accurate." 



n Memoires deV Academic des Sciences, 1790, 



