1 If the invitation says black tie, women should wear a floor-length, evening gown. 2  A tuxedo is mandatory if you're a man. 3  This is your chance to dress as if you were headed to the Oscars. 4  Black tie optional means that wearing a tuxedo or long evening gown is not mandatory, but guests should feel free to do so.
Ether is an organic functional group consisting of a disubstituted oxygen, or an oxygen atom bonded to 2 carbon atoms (if adjacent to a ketone, functional group is then called an ester).
Petroleum ether is the petroleum fraction consisting of Câ and Câ hydrocarbons and boiling in the range 35â60 â; commonly used as a laboratory solvent. The term ether is used only figuratively, signifying extreme lightness and volatility.IN 51630 provides for Petroleum spirit (also called here Spezialbenzine-Petrolether) which is described as a special boiling-point spirit commonly used in laboratory applications, having high volatility and low aromatics content.. Its initial boiling point is above 25 â, its final boiling point up to 80 â.