174 PHOSPHORESCENCE. 



In 1686, Tachard, an ecclesiastic, in order to 

 explain the phosphorescence of the sea, stated 

 that the waters of the ocean absorbed the light of 

 the sun by day and emitted it again at night. 

 The distinguished philosopher Eobert Boyle, who 

 lived at this period, believed that the light of 

 the waves was owing to friction. He imagined 

 that the atmosphere rubbed against the water of 

 the sea by the rotation of the earth, and that 

 this friction had for direct effect the emission of 

 a certain amount of caloric and light. We have 

 already seen that Boyle endeavoured also, by 

 numerous and ingenious experiments, to account 

 for the phosphorescence of rotten wood, flesh, etc. 



Later still, we find that Mayer reproduces the 

 old opinion of Tachard ; and Beccaria affirms that 

 the solar-phosphorus, or Bologna stone, " absorbs 

 light, and emits it some time .afterwards." Bec- 

 caria thought he had observed that this substance, 

 when submitted to coloured light from red, yellow, 

 blue, and green glasses, shone in the dark with a 

 red, yellow, blue, or green light. But this was 

 afterwards distinctly denied by Wilson in England, 

 Zanetti and Algerotti in Italy, by Dufay in France, 

 and by Grosser of Vienna. 



In 1797, Brugnatelli published a singular opi- 

 nion in the ' Annali di Chimica/ He believed 

 that the phosphorescence of the Lampyridce, or 

 glowworms, was owing to a peculiar physiological 



