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GOLD. 
GOLD, which is the denfeft of all the metals,, 
imparts a red colour to glafsy whenever it is divided 
into particles fo minute, that it can be intimately 
mixed with the ingredients of which the glafs is 
made ; and it feems indifferent in what manner it is 
reduced to this ftate. Thus 
1. From the powder obtained by rubbing gold 
with a pumice ftone, ufed by the goldfmiths 
in polifhing it, mixed with nitre, borax, and 
potafh, a beautiful red glafs is produced [<j]. 
2. When a fmall quantity of a folution of gold in 
aqua regia is evaporated on a glafs plate, with 
a gentle heat, that part of the glafs on which it 
lay thinned;, is tinged red^ by the entrance of 
the particles of gold into it’s furface [/^]. 
3. Artificial rubies are made by mixing w'nh glafs y 
gold diffolved in aqua regia, and afterwards cal- 
cined in the furnace [c]. 
[fl] Sol fine vefte, cap. 8. 
Junker, Confpc( 5 tus Chem. tab. xxxiii. de Auro, p. 852. 
Aiirum detritum pumice, feu pulvis auri pumice, quo aurl- 
fabri fua opera poliunt et abradunt, commiftus, Gold-Schliff, fi 
cum ana nitri, boracis, ct cinerum clavellatorum liquido funda- 
tur, praebet vitrum^ inftar optimi opificum encauftici, 7 'ubro colore 
pellucidum, fubfidentibus paucis auri granulis ; leftante autore 
Solis fine vcfte. 
Shaw on Boerhaave’s Chem. vol. i. p. 79. Gold ground with 
pumice, and afterwards fufed with equal parts of nitre, borax, 
and pot afhes, affords a fine tranfparent red glafs. 
[^] Philof. Tranf. N°. 286. 
[f] Neri’s art of Glafs, chap. i2g. 
Calcine Gold with aqua regia many times, pouring the water 
upon it five or fix times : then put this powder of Gold in 
4. Kunkcl 
