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manner, Sal. Ammoniac. ; more yet, Sal catharticum 
and Nitre ; weak in the Natron of the Ancients, 
and Alum; but brighteft of all in Borax. 
In the vegetable Kingdom we find very few Thof- 
phoriithat of dry rotten Wood is weak, and not lad- 
ing; it appears chiefly upon the Edges and Inequali- 
ties of the Surface. But this is moft remarkable in 
the rotten Wood of the Fir-tree, and fome others, 
where in the dark you fee fhining Spots as big as 
Tares; whereas, in full Light, the whole Surface 
appears alike. Some few Barks are luminous, but 
not confiderably fo; but no Fruits, Seeds, or their 
Meals. Cotton appears very bright, and the Cryftals 
of Tartar ; but fine Loaf Sugar appears the moft lumi- 
nous of all, both without and within. Gums and 
Refins retain no Light. 
There is a vafl Variety of Bhofphori in the animal 
Kingdom, fuch as the Bones and Teeth ; to thefe may 
be added the Shells of Fifh, Egg-fhells, the human Cal- 
culus, Bezoar, and in whatever Parts of Animals the ter- 
reftrial Principle is very predominant. But where there 
is a confiderable Quantity of oily Matter, as in the 
Hoofs, Horns, and Feathers, no Light is manifeft. 
The Author, having gone throngh the natural 
Phojphori, propofes fome Queries concerning them ; 
of which the firft is, In what and how great a 
Light the Object ought to be placed ? He tried 
different Thofphori indifferent Degrees of Light, and 
found them imbibe moft Light from the Sun itfelf ; 
next in Quantity, when the Sky was clear ; and the 
lead in foggy W eathcr. Thefe Experiments fhould be 
made in the open Air, and not in a Houfe with the 
glafs Windows fhuv; becaufe many Bodies appear 
luminous, 
