DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.19571#0281
THE ARTIST'S ASSISTANT. 267
Wood a flies, by which is to be underftood, like-
wife, thofe of broom, furze, or any other burnt vege-
table, are ufed as a flux for the common bottle or
green glafs; the afhes muft be taken in their original
ftate, confiding of the calcined earth of the vegetable,
and their lixiviate, or fixed alkaline fait; as their vir-
tue lies in their original manner of commixture ; for
this very extraordinary circumftance attends them,
that though in their primitive ftate, they vitrify
- eafily and act as a ftrong flux to any of the vitrefcible
earths or Hones; yet, if the falts be feparated from
the earth, by folution in water, the earth from,
that time becomes extremely repugnant to vitrifica-
tion; and, though the fame falts which were taken
away from it, or even a much larger quantity be
again added to it, it refifts their fluxing power, and
difplays a nature intirely different from that which,
it appeared to have before its feparation from the
farts. There is no preparation neceffary for thefe
afhes, in order to their entering into the compofition
of alafs. exceDt the lifting them, to free them from all
the fragments of charcoal, or unburnt parts of vege-
tables employed in their production ; but they fhould
be carefully kept from damp and moifture, which
would make the falts deliquiate, and run off from the
earth : the goodncfs of thefe afhes muft be dii'tin-
guifhed by their appearing free from impurities, and
by their whitenefs ; and their abounding in fait, is
Kkewife a proof of their excellence, which may be
examined by making a lixivium of any-known fmall
quantity, and judging of its weight.,
Of the feveral kinds of white glafs, and their com-
pofitions in general:—The feveral kinds of white
tranfparent glafs now inufe, in this part of the world,
L 1 2 are
Wood a flies, by which is to be underftood, like-
wife, thofe of broom, furze, or any other burnt vege-
table, are ufed as a flux for the common bottle or
green glafs; the afhes muft be taken in their original
ftate, confiding of the calcined earth of the vegetable,
and their lixiviate, or fixed alkaline fait; as their vir-
tue lies in their original manner of commixture ; for
this very extraordinary circumftance attends them,
that though in their primitive ftate, they vitrify
- eafily and act as a ftrong flux to any of the vitrefcible
earths or Hones; yet, if the falts be feparated from
the earth, by folution in water, the earth from,
that time becomes extremely repugnant to vitrifica-
tion; and, though the fame falts which were taken
away from it, or even a much larger quantity be
again added to it, it refifts their fluxing power, and
difplays a nature intirely different from that which,
it appeared to have before its feparation from the
farts. There is no preparation neceffary for thefe
afhes, in order to their entering into the compofition
of alafs. exceDt the lifting them, to free them from all
the fragments of charcoal, or unburnt parts of vege-
tables employed in their production ; but they fhould
be carefully kept from damp and moifture, which
would make the falts deliquiate, and run off from the
earth : the goodncfs of thefe afhes muft be dii'tin-
guifhed by their appearing free from impurities, and
by their whitenefs ; and their abounding in fait, is
Kkewife a proof of their excellence, which may be
examined by making a lixivium of any-known fmall
quantity, and judging of its weight.,
Of the feveral kinds of white glafs, and their com-
pofitions in general:—The feveral kinds of white
tranfparent glafs now inufe, in this part of the world,
L 1 2 are