410 PHILOSOPHICAL TRANSACTIONS. [aNNO I7O8. 



I have tried all or most of the other precious stones, but could find no such 

 phenomenon in any of them. All these experiments were made at the latter 

 end of May and beginning of June, and therefore I cannot pretend to account 

 for the phaenomena that may attend experiments made while the sun is on the 

 other side of the equator. 



Some other bodies are known to afford light, and perhaps there are many more 

 which remain yet undiscovered; but I am well assured, that all or most of the 

 bodies which have an electricity, yield light; for it is the light that is in them, 

 that is the cause of their being electral ; yet this electricity never shows itself 

 without friction ; if you rub any body that has an electricity, and apply it near 

 to some light bodies, as particularly very thin slices of cork, it will put them 

 into a great agitation, and make them seem to the eye as if hanging at the 

 body by a fine hair. Jet seems to be a kind of black amber, having most of 

 the same properties, though less perfect and pure. 



Another natural phosphorus, or noctiluca, is gum lac, and also red sealing- 

 wax, which is made of gum lac and cinnabar, the cinnabar no way impeding 

 but rather promoting its luminous quality ; for I caused long taper rolls to be 

 made up of lac alone, and of pure red sealing-wax, both being well polished ; 

 the sealing-wax, upon friction, seems to emit its crackling and light sooner than 

 the lac, which I impute to the cinnabar constringing its parts; though I think 

 lac by itself has the greatest electricity, both having all or most of the pro- 

 perties of amber; and by all the trials I have hitherto made of lac and sealing- 

 wax, I find that though the cracklings are as plentiful in the day-time, as when 

 the sun is down, yet in the darkest places I could discover but a little appear- 

 ance of light. I know not in the animal kingdom any thing except pismires 

 that affords a volatile acid; and in the East-Indies there is a large kind of them, 

 that live on the sap of certain plants, yielding both a gum and a colour ; which 

 sap, passing through the body of these insects, is by their acid spirit converted 

 into an animal nature ; which is the reason that with the colour extracted from 

 gum lac (which is nothing else but the excrement of these insects) almost as 

 good and full as lasting colours are made, as from cochineal : I am the more 

 confirmed in this, because I know of an artificial way of converting vegetable 

 colours into an animal nature, very much like this, by which the colours are 

 made more pleasant and permanent. After the same manner, the remaining 

 gum, which is an oleosum, being digested, and passing through the bodies 

 of those insects, is by their volatile acid converted into a vegetable animal 

 phosphorus, or noctiluca. The artificial phosphorus is a mineral animal phos- 

 phorus ; whereas I take the others to be altogether mineral. 



