130 History of Luminescence 



In Hooke's Cutler Lectures '** there is a tract entitled Cometa, 

 published in 1678, which dealt not only with the Comet of April 

 1677, but also with " Mr. Boyle's Observation made on two new 

 Phosphor! of Mr. Baldwin and Mr. Craft." This section is an eye- 

 witness account by Boyle of Mr. Craft's exhibit of his " Artificial 

 Substance, that shines without any precedent illustration." The 

 demonstration took place after supper September 15, 1677, and 

 Mr. Craft is continually referred to as " the Artist." These observa- 

 tions on the element phosphorus describe various phenomena, espe- 

 cially writing on paper in self-luminous letters. They were intro- 

 duced by Hooke apropos of a discussion of the light of the comet's 

 tail. He took the position that one could not argue that the light 

 of the tail was like " a sulphureous vapor exhaled from the earth 

 and kindled above," because there were " very many and these very 

 differing " ways of producing light, which he then proceeded to 

 enumerate. 



These various methods were restated, together with some new 

 ones, in Hooke's " Lectures on light, explicating its nature, proper- 

 ties and effects," read about the beginning of 1680, and published 

 in Posthumous Works (pp. 71-148) . The luminescences were 

 divided into three categories (p. 112) : 



(1) Bodies shining without Heat, by an inward Fermentation [as] 

 Glow-worms, Scolopendra, several kinds of Flies, decaying Fish, as Whit- 

 ings, Oysters, and many others, sometimes Flesh, as Veal, also rotten 

 Wood, and some sorts of Putrifying Vegetables, also some putrifying 

 Urines; also the Phosphorus made out of the Caput mortuum, or the 

 Rob ^^ of Urine found out by Dr. Kunkell, and many others. (2) " such 

 as shine by Impression of Light made upon them, by being exposed only 

 to the Light of the Sun or Day " as Bononian and Balduinian Phos- 

 phorus. (3) such as shine by Motion, Diamants, Sea water, some sort 

 of Dews, Sugar, Black Silk, the Back of a Cat, and clean warmed Linnen, 

 and several other Substances which will shine with a degree of Motion 

 or a little rubbing. 



He included here iron hammered till red hot or flints struck against 

 each other. 



Hooke also experimented with Baldwin's phosphorus given him 

 by Dr. Slare, which " was found to be very receptive of light " ^^ 



^* Reprinted in facsimile as vol. 8 of R. T. Gunther, Early science in Oxford, 270, 

 Oxford, 1931. Lectiones Cutlerianae, 1674-1679. 



^^ A syrup of fruit juices. The word "rob" was apparently applied to concentrated 

 wine. Caput mortuum refers to the worthless residue of a distillatum, in this case 

 not so worthless. 



^^ R. T. Gunther, Early science in Oxford, 7: 517 and 540, 1930. Part II of Life and 

 work of R. Hooke. 



