142 History of Luminescence 



yet because some Watry and Aiery plyable parts, are mingled with them, 

 they have the power to kindle heat and fire, but not of receiving the 

 action of Light. Hence it is that when the Spirit of Vitriol and Oyl of 

 Tartar are poured together, an effervescence or boyling is caused, be- 

 cause the free passage of the subtil matter being hindered in them, doth 

 produce a wrestling or contest betwixt these two liquors which is the 

 cause of a vehement heat. . . . 



Quick lime sprinkled with water waxeth hot because its parts are so 

 suited and disposed as to admit the water surrounded only with the 

 matter of the 1st Element; so that the Globuli, being expelled, the matter 

 of the 1st Element only bears sway. For those Bodies are said to have 

 the form of Fire whose particles do separately comply with the motion 

 of the 1st Element and imitate the agitation thereof. . . . 



When a Cats Back is strongly rubb'd with ones hand, sparks of Fire 

 seem to proceed from them. 



The Reason whereof seems to be this, because this Rubbing drives 

 out some Particles of Moisture and causes them to be dissipated into 

 the Air whereupon the particles of the fire, or if you will, the Sulphureus, 

 greasy Particles, wherewith the Hair and Skins of Animals do abound; 

 and those of Cats more than any other, croud and meet together, whence 

 proceeds fire, and from the fire, light. Now this fiery Stream, or Exhala- 

 tion, is easily retained or kept close in this Thicket of Hair, which con- 

 sisting wholly of Sulphureous filaments, becomes easily entangled amongst 

 the said Hairs. Which is the true Reason, why a Garment lin'd with 

 Fur doth so obstinately retain the heat committed to it, and keep off the 

 Cold. But it is to be noted, that these sparks of Light, which by stroak- 

 ing are forc'd from the Back of a Cat, do only appear in the Dark, be- 

 cause a greater Light obscures and swallows them, as the Light of the 

 Sun does that of the Stars. 



Here we have the observations and the explanation of many kinds 

 of luminescence according to a system of philosophy which Le Grand 

 was ready to defend at all costs. This method of presentation is very 

 characteristic of French science *"' of that day and is particularly well 

 show^n in the next section by the ingenious explanations of the 

 chemist, Lemery. Quite naturally, he devoted considerably more 



'* Another Frenchman, Edme Mariotte {ca. 1620-1684) of Dijon, treated lumines- 

 cence briefly in his book, Traite de la nature des coule\irs (Paris, 1688) . He noted 

 that the flame of wood may be white, yellow, red, or blue, that of charcoal is red, 

 and that of molten copper appears either blue or green, while the flame of sulphur 

 and that of spirit of wine are blue. Rotten wood, the glowworm, and scales of some 

 marine fish emit a light which also approaches blue. In this category, Mariotte also 

 placed the artificial phosphors, " the blue light of sea water when agitated, and the 

 light which appears when certain parts of the flesh of some animals begins to spoil." 

 The light of these luminescences is blue " because of the fineness (subtilite) of some 

 exhalations of volatile salt or of sulphureous material which give off no sensible heat 

 whatever. It is true they resemble but are not like a flaming material, as water does 

 not put out their light and they are not consumed." 



