Section 26(4) in The Indian Post Office Rules, 1933
(4)Liquids, oils and substances which easily liquefy shall e enclosed in receptacles hermetically sealed. Each receptacle shall be placed in a special box of metal or of strong wood or of strong corrugated cardboard containing saw-dust, cotton, or spongy material in sufficient quantity to absorb the liquid in case the receptacle be broken. The lid of the box shall be fastened down in such a manner that it will not easily be detached.
