292 OBSERVATIONS ON' THE TRKMOLllR. 



refcent the tre- Among thefe carbonates of lime, which conititute the gangiflfc 

 mo e is no o. Q p ^ Q tremolite, and very frequently belong to the fpecies. 

 which is called dolomie, a great number are endowed with 

 the double phofphorefcence ; but, on the other hand, we meet 

 with feveral, in which not the flighted trace of this property- 

 can be found. The tremolites inelofed in the firfr partake^ 

 though in rather an inferior degree, of their phofphorefcence, 

 whereas thofe which are inelofed in a non-phofphorefcent car* 

 bonate of lime are equally void of that property. 

 That the phof- From the very firll moment when I obferved this fact, it oc- 

 fr h or!nterpoL°d e curred to me > that the phofphorefcence of the tremolite might 

 carbonate of very probably proceed merely from that of the carbonate of 

 {| m ^ k ^^ u ved lime, which undoubtedly is interpofed between its parts. I 

 by nitric acid, therefore (elected fome cryilals that were inelofed in phofpho- 

 ■which deftroyed r elcent carbonate of lime, and after having fatisfied myfelf 

 • uality. that they were themfelves phofphorefcent, both by friction 



and by the aclion of heat, I digefted them for fome time in ni- 

 tric acid. When I took them out, their furface was perfo- 

 rated with fmall cavities, occafitJfWd by the folution of the por- 

 tions of carbonate of lime, and friclion was then incapable of 

 making them difplay the flighted phofphorefcent light. This 

 light, however, was emitted, at the point immediately 

 after ignition, though in an extremely weakened degree. I 

 afterwards reduced fome of the fame cryftals to a coarfe pow- 

 der, and this powder having remained again for fome time in 

 the acid, was intirely deprived of all its phofphorefcent pro- 

 perty. 

 This quaKty I could no longer doubt that the carbonate of lime, inter- 



therefore belongs p f ed b etween t i le p ar ticles of the tremolite was the real caufe 

 and not the fpe- of the phofphorefcence of this fubftance, when its gangue was 

 cIes * endowed with the fame property. It therefore appeared to 



me to be at the fame time perfectly proved, that phofphoref- 

 cence cannot be ranked amongft the characters of the fpecies 

 in this fubftance, and that it ought to be confidered merely as 

 diftinelive of one of its varieties. 

 Whether the A new doubt, which was a very natural confequence of this 



large portion of obfervation, now prefented itfelf. Could it be true, that the 

 in tremolite can h'me which chemifts have reckoned to amount to ^ 6 \ amongft 

 be admitted as a the conftituent parts of the tremolite, does exift in it in fo 

 wjlitutntfart? Jarge a p ro p ortion . In orf j e r, ifpoflible, to fatisfy this doubt, 

 I fele&ed fome cryftals of non-phofphorefcent tremolite, which 

 2 - had 



