Journal . n a High Temperature Zeit. 12, 184. The presence of small quantities of iron in kaolin used forthe manufacture of porcelain has led to the idea that thisimpurity is the cause of the yellowish colour which some-times results, at least in cases where an oxidising flame isused; with :i re<luciug flame the porcelain would have ablue-grceu tinge due to the ferrous salts. This is not so;at the high temperatures employed in the furnace neitherferrous nor ferric oxide result; the magnetic oxide of iron(FcjOj) is formed, and this colours the porcelain from greyto black accord
Journal . n a High Temperature Zeit. 12, 184. The presence of small quantities of iron in kaolin used forthe manufacture of porcelain has led to the idea that thisimpurity is the cause of the yellowish colour which some-times results, at least in cases where an oxidising flame isused; with :i re<luciug flame the porcelain would have ablue-grceu tinge due to the ferrous salts. This is not so;at the high temperatures employed in the furnace neitherferrous nor ferric oxide result; the magnetic oxide of iron(FcjOj) is formed, and this colours the porcelain from greyto black according to the ciuantity present. The yellow-colour of porcelain is not due to iron at all, but to thereduction of alkaline sulphates to suli)hides by a smoky-flame. In the manufacture of glass, iron behaves similarly,forming the magnetic oxide of iron ; by adding a sufiieieutamount of ferric oxide to the melted glass and allowing it tocool slowly, crystals of the magnetic oxide separate in themass.—C. A. ^^:^ ^.^-^ ^^^^^^^^^ 111 4^TPi t^*: u: W 4-- ^tS* FIC 2 IT ^-?-^—i—~ m ^^i==: 2^ 1^774 T zn «^ =lSt^=544^}=^=^ *e* .riv_ ^^t^ 9/, IZT tct =J5t Z^ t^TF*
Size: 2308px × 1083px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectchemist, bookyear1882
