VOL. XLIV.] PHILOSOPHICAL TRANSACTIONS. 209 



An Account of a Booh intitled, De quamplurimis Phosphoris nunc primum detectis 



Commentarius. Auctore Jac. Barthol. Beccario, Ato. Bolognia, 1 744. 



Extracted and translated from, the Latin by IV. JVatson, F.R.S. N° 478, p. 81. 



The ingenious author, in the work before us, does not treat expressly on 

 those productions of the chemical art, which we usually call phosphori ; but prin- 

 cipally of such substances, whether natural or artificial, as imbibe the rays of 

 light in such quantities, and in such a manner, as to appear luminous for a time, 

 even in absolute darkness. 



The author divides the phosphori into several kinds, some of which shine of 

 themselves naturally, as the glow-worm and dates, or adventitiously, as the flesh 

 of animals which most probably arises from a degree of putrefaction, sometimes 

 too slight to be obvious to our senses. Other bodies become luminous by attri- 

 tion, heat, the free access of air, and, lastly, by imbibing and retaining the 

 rays of light. Those bodies that are luminous by attrition are, among others, 

 some diamonds, and the hairs of animals; by heat, several sorts of gems, and 

 mountain crystals; from the free access of air, the phosphori of Kraft and Horn- - 

 berg; from the aspect of light, the Bolognian luminous stone, the preparation 

 by Christian Adolphus Baldwin of chalk dissolved in spirit of nitre, as well as 

 several others discovered by the late Mons. Du Fay, who found, that whatever 

 substances would, by calcination, be converted into a calx, or whose concrete, 

 from a solution in the acid of nitre, would bear fire enough to become red-hot, 

 these bodies were adapted to imbibe and retain light. 



The greatest number of phosphori are of the last mentioned kind, and these 

 are principally the subjects of this treatise. Some of these are natural, others 

 artificial; but of these last, the preparation is so slight, as not to change the 

 nature of their constituent parts. The natural phosphori are either fossil, 

 vegetable, or animal. The fossil are, though very different in degree, some 

 sorts of earths, white sand, lime-stones, stalactites, and several other figured 

 stones, Iceland crystals, flints, some species of agates, white arsenic; but no sort 

 of metals, metallic or sulphureous bodies, as jet, amber; except the beforemen- 

 tioned arsenic. On the other hand, salts imbibe light, provided they are divested 

 of every metallic principle; otherwise not, though pellucid as possible. For this 

 reason, none of the vitriols will imbibe light; but other salts will, though with 

 a considerable difference as to quantity; for sal gem. and rock-salt imbibe very 

 little, sea-salt, if dry, and in crystals, much more ; and in like manner sal am- 

 moniac; more yet, sal catharticum and nitre; weak in the natron of the ancients, 

 and alum; but brightest of all in borax. 



In the vegetable kingdom we find very few phosphori ; that of dry rotten wood 

 is weak, and not lasting; it appears chiefly on the edges and inequalities of the 



VOL. IX. E K 



