72 Professor T, E. Thorpe [March 14, 



WEEKLY EVENING MEETING, 



Friday, March 14, 1890. 



William Ckookes, Esq. F.R.S. Vice President, in the Chair. 

 Professor T. E. Thorpe, Ph.D. F.R.S. M.B.I. 



The Gloiv of Phosphorus. 



The word phosphorus — originally applied to any substance, solid or 

 liquid, which had the property of shining in the dark — has gradually 

 lost its generic sense, and is nowadays practically restricted, as a 

 designation, to the waxlike inflammable substance which plays such an 

 important part in the composition of an ordinary lucifer match. 

 Phosphorus, indeed, is one of the most remarkable of the many remark- 

 able substances known to the chemist. The curious method of its 

 discovery ; the universality of its distribution ; its intimate connection 

 with the phenomena of animal and vegetable life ; its extraordinary 

 physical properties and chemical activity; its abnormal molecular 

 constitution ; the Protean ease of its allotropic transformations — all 

 combine to make up a history which abundantly justifies its old 

 appellation of phosphorus mirahilis. 



Godfrey Hankewitz, more than 150 years ago, wTote : " This phos- 

 phorus is a subject that occupies much the thoughts and fancies of 

 some alchymists who work on microcosmical substances, and out of 

 it they promise themselves golden mountains." Certainly no man 

 of his time made more in the way of gold out of phosj)horus than did 

 Mr. Hankewitz, for, at his little shop in the Strand, he enjoyed for 

 many years the monopoly of its sale, guarding his Arcana with 

 all the jealousy of a modern manufacturer of the element. 



Phosphorus, or, as it was then called, noctiluca, was first seen in 

 this country in 1677. It was shown to Robert Boyle, who had already 

 worked on phosphorescence in general, and who seems to have been 

 specially struclc with the remarkable peculiarity of a factitious body 

 which could be made " to shine in the dark without having been before 

 illumined by any lucid substance, and without being hot as to sense." 

 In these respects the substance difiered from all the phosphoj-i hitherto 

 known. The conditions which determine its glow were the subject 

 of the earliest observations on phosphorus, and Boyle has left us a 

 minute account of his work on this point. In the first place, he noticed 

 that the substance was only luminous in presence of air. He accu- 

 rately describes the nature of the light, and noticed that the water 

 in which the phosphorus was partially immersed acquired a " strong 

 and penetrant taste .... and relished a little like vitriol." " On 

 evaporation it would not shoot into crystals . . . but coagulated into 

 a substance like a gelly, or the whites of eggs, which would be easily 

 melted by heat." On heating this " gelly " it gave off " flashes of fire 



