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SECT. XXVII. 
Some of thefe bodies melt to a colourkfs tranf* 
parent glafs with the borax ^ for inllance, the 
Calcareous Subilances, when pure, the Fiuores, 
feme of the Zeolites, &:c. Others tinge the borax 
with a green tran {parent colour *, viz. ^tQranatea^ 
T rapp^ home of the Argillace^^ fome of the Jdicar 
ce^e 2ii\^ AJhefiince : This green has its origin, partly 
from a fmall portion of iron, which the Grdnatea 
particularly contain, and partly from phlogifton. 
SECT, XXVIII. 
The borax cannot diflblve but a certain quan- 
tity of a mineral body proportional to its own; 
Of the calcarepus kind it difiblves a vaft quantity, 
but turns at laib, when too much has been added, 
from a clear, tranfparent, to a white, opaque flag. 
When the quantity of the calcareous matter ex- 
ceeds but little in proportion, the glafs looks very 
clear as long as it remains hot ; but as foon as it 
begins to cool, a white half opaque cloud is feen 
to arlfe from the bottom, which fpreads over the 
third, half, or more of the glafs globe, in propor- 
tion to the quantity qf calcareous inatter *, but the 
glafs or Hag is neverthelefs fhiping, and of a glaffy 
texture when broke ; if more of this matter be 
added, the cloud rifes quicker and more opaque, 
and fo by degrees till the flag becomes quite milk 
white : It is then no more of a ihining, but rather 
appearance, on the furface y is very brittle, and 
pf a graiped texture, when broke. 
SECT. 
