are amongft others, fome Diamonds, and the Hairs of 
Animals ; by Heat, feveral Sorts of Gems, and Moun- 
tain Cryftals ; from the free Accefs of Air, the Phof- 
phori of Kraft and Homberg ; from the Afpeft of 
Light, the Bolognian luminous Stone, the Prepara- 
tion by Chriftian Adolphus Baldwin of Chalk difi* 
folved in Spirit of Nitre, as well as feveral others 
difcovered by the late Monfieur Du Fay , who found, 
that whatever Subftances would, by Calcination, be 
converted into a Calx, or whofe Concrete, from a 
Solution in the Acid of Nitre, would bear Fire enough 
to become red-hot, thefe Bodies were adapted to 
imbibe and retain Light. 
The greateft Number of Phofphori are of the laft- 
mention’d Kind, and thefe are principally the Sub- 
jects of this Treatife. Some of thefe are natural, 
others artificial ; but of thefe laft the Preparation is 
fo flight, as not to change the Nature of their con~ 
ftituent Parts. The natural Phofphori are either foffil, 
vegetable, or animal. The foffil are, though very 
different in Degree, fome Sorts of Earths, white 
Sand, Lime-ftones, Staladlites, and feveral other 
figured Stones, Ifland Cryftals, Flints, fome Species 
of Agates, white Arfenic ; but no fort of Metals, 
metallic or fulphureous Bodies, as Jer, Amber ; ex- 
cept the before-mention’d Arfenic. On the other 
hand, Salts imbibe Light, provided they are diverted 
of every metallic Principle ; otherwife not, though 
pellucid as poffible. For this Reafon, none of the 
Vitriols will imbibe Light j but other Salts will, tho’ 
with a confiderable Difference as to Quantity ; for 
Sal Gem. and Rock-Salt imbibe very little ; Sea-Salt, 
if dry, and in Cryftals, much more; and, in like 
L 2 manner, 
