Question

Why does window glass of old building looks milky

Answer 1

HELLO FRIEND HERE IS YOUR ANSWER.
Glass is an amorphous solids and it is also called supercooled liquid.Hence like liquids it hastendency to flow. therefore in old buildings the bottom of the glass panes look milky in appearence or thicker because glass over the years flown down under the influence of gravity.
i hope it will help you.
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Answer 2

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The window panes of buildings are exposed to continuous heat and change in temperature heat from day to night which converts the amorphous glass to crystalline form. This process is very slow just like the flow in glass. ... Therefore, the window panes of old buildings appear milky.