Chap. 38.] Lights about the Beds of Sick Perjons. 255 



the fea entirely proceeds from the putrefcent parts of 

 marine animals *. 



Human bodies, as well as thofe of other animals, 

 emit light juft when they begin to putrify,- and the 

 \valls and roofs of places in which dead bodies have 

 often been expofed have been obferved to have a 

 flimy matter depofited on them, which was luminous 

 in the dark. The lights which are fometimes feen in 

 burial grounds undoubtedly proceed from this caufe 

 alone f. Similar appearances have been obferved 

 about the beds of lick perfons, probably in putrid 

 difeafes: one of thefe was obferved about the body and 

 the bed of a fick woman at Milan, which fled from the 

 hand that approached it, but was at length difperfed 

 by a ftream of air. It is well known that the iweat 

 often contains a confiderable quantity of phofphoric 

 matter j and the fact, which has now been ftated, 

 is ftrongly confirmed by a circumftance related by 

 Henckel, in his Pyritologia. One of.hr. friends, who 

 was of a fanguine temperament, had indulged himfe'lf 

 in the exercife of dancing tofuch excefs,and his perfpi- 

 ration was fb profufe, that he imagined his life in dan- 

 ger. While he undreffed, traces of phofphoric light 

 were feen on his Ihirt, and in thofe parts were a num- 

 ber of reddifh yellow fpots, exactly refembling the 

 concrete phofphoric acid. 



In all thofe animal exhalations, which exhibit phof- 

 phoric appearances, the phofphorus in the ftate of a gas 

 is mixed with hydrogen, and the compound is called 

 fbejpborated hydrogen gas. Of this nature, probably, 

 are many of thofe phenomena, which are clafled 

 under the general name of ignes fatui, and of thofe 

 which were defcribed in a fprmer volume as igneous 

 or luminous meteors. 



* PrifJ}. Of. 576. f Ib^d. 



