388 History of Luminescence 



Later observations on crystalloluminescence were made by Jons 

 Jacob Berzelius (1779-1848) and Friedrich Wohler (1800-1882) in 

 1823, and F. Penny in 1855. They noticed the sparkling light dur- 

 ing the crystallization of K2SO4, and that the newly formed crystals 

 would leave a streak of light if they were stroked, i. e., a long-lasting 

 triboluminescence. The phenomenon was lost if the crystals were 

 redissolved and again crystallized. C. H. Pfaff (1815) added 

 Sr(N03)o, K. S. L. Hermann (1824) added cobalt sulphate and 

 potash and A. M. Pleischl (1835) added KHSO4 to the list of crys- 

 talloluminescent substances. Most of these papers appeared in 

 J. S. C. Schweigger's Journal fiir Chemie und Physik, and led 

 Schweigger (1823-1825) to comment on the crystalloluminescences, 

 classifying them as electrical phenomena and referring to " Krys- 

 tallelectricitat " as a general natural principle. He was particularly 

 interested in Dobereiner's new " Feuerprincip " (platinum sponge) 

 and discussed the glow of finely divided platinum under certain 

 circumstances. This led J. W. Dobereiner (1780-1849) to publish 

 an account of Biichner (1824) of " the wonderful spectacle of con- 

 tinuous spray of sparks " when benzoic acid is sublimed in a tall 

 glass tube. Dobereiner declared that the benzoic acid luminescence 

 was a crystalloelectric phenomenon, similar to that observed when 

 manganese dioxide and potassium chlorate are heated for prepara- 

 tion of oxygen. 



It is possible that electrical discharges accompany some types of 

 crystallization. Professor Pontus (1833) described a bright spark 

 which appeared at the end of a small glass ampule containing water 

 a moment before solidification. The water was frozen rapidly by 

 covering the glass ampule with ether-soaked cotton and placing in 

 a vacuum. The experiment was repeated and confirmed by J. S. E. 

 Julia-Fontenelle (1780-1842) . Fontenelle discussed the effect with 

 A. C. Becquerel, who merely mentioned that a similar scintillation 

 occurred during the formation of other crystals.^' 



A quite new compound was discovered and studied in 1835 by 

 Heinrich Rose (1795-1864), professor of chemistry at the Univer- 

 sity of Berlin. This was arsenious acid, whose luminescence on 

 crystal formation Rose described as bright enough to light up the 

 whole room. The ability to emit light would last for two or three 

 days, if the solution was stirred. He determined the conditions 



^■^ What appears to be triboluminescence of ice was described by Wasstrom (Crell's 

 Chem. Ann., 392, 1799, translated from Neues Schwedischen Abhand., 1798) , who 

 explained the light of the sea in cold regions by the light fiom ice crystals rubbing 

 against each other. In recent times, both J. Dewar (1901) and H. Becquerel (1901) 

 have observed light from ice cooled to liquid air temperatures, presumably a tribo- 

 luminescence connected with fracture of crystals. 



