268 History of Luminescence 



Hermbstadt (1760-1833) , a physician and royal apothecary in Berlin, 

 in 1808, both described men whose sweat was luminous, especially 

 when rubbed or on removing clothing. Although the light was 

 attributed to the sweat, and was thought to be due to sahs eaten by 

 the men, the accounts suggest that electric discharges were respon- 

 sible for the lisfht at the time their clothes were removed. 



Such " lucid effluvia in animals " were supposed to be a kind of 

 burning or were explained by the principles of fermentation. Only 

 as a result of the growing interest in electricity was the true origin 

 of the light generally accepted, a connection which will be traced in 

 the next section. 



RELATION TO ELECTRICITY 



Although Stephen Gray (1720) noted the light when silk wool 

 was pulled through the fingers, and knew the effect was electrical, 

 he made no mention of ignis lambens. One of the first cases to 

 which an electrical origin was applied (by H. Miles in 1745) , was 

 an old one, that of Mrs. Suzanna Sewall, wife of Major Sewall and 

 daughter of Lord Baltimore, described in a letter from William 

 Digges to the Reverend John Clayton at James City, Virginia, and 

 sent by him to Robert Boyle under date of June 23, 1684: 



There happened about the Month of November to one Mrs. Susanna 

 Sewall: ... a strange Flashing of Sparks (seem'd to be of Fire) in all 



the wearing Apparel she put on, and so continued until Candlemas 



The said Susanna did send several of her wearing Apparel; and, when 

 they were shaken, it would fly out in sparks, and make a noise much like 

 unto Bay-leaves when flung into the fire; and one spark litt on Major 

 Sewall's Thumb-nail, and there continued at least a Minute before it 

 went out, without any Heat: All which happend in the Company of 

 Wm. Digges, my Lady Baltimore, etc. . . . 



They caused Mrs. Susanna Sewall one Day to put on her sister Digges's 

 Petticoat, which they had tried beforehand, and would not sparkle, but 

 at Night when Madam Sewall put it off, it would sparkle as tlie rest of 

 her own Garments did.-^ 



The letter was read before the Royal Society in 1745 by the 

 Reverend Henry Miles, F. R. S., parson at Totiting in Surrey and a 

 writer on electrical matters. He proceeded to explain the effect 

 as due to electricity rather than " fermentation." He wrote: " I 

 humbly apprehend, the Properties of the Effluvia in animal Bodies 

 are many of them common with those produced from Glass, etc.; 

 such as their being lucid, their Snapping and their not being excited 

 without some Degree of Friction, and I presume, I may add Elec- 

 ts From H. Miles, Phil. Trans. 43:441-446, 1745. 



