1 To delete one or multiple messages from a conversation or thread, click Messages on the left side of your homepage.The Messages can be found on the upper left side of the News Feed screen. 2  Select the conversation or thread you want to delete messages from. 3  Scroll up until you reach the message youâd like to delete.
Uses. Oxygen is of great importance in the chemical and the iron and steel industries. Its major use is in steel production, for example in the Bessemer process. The oxyacetylene torch is another important industrial application.Oxygen is utilized in medicine in the treatment of respiratory diseases and is mixed with other gases for respiration in submarines, high-flying aircraft, and spacecraft.ts major use is in steel production, for example in the Bessemer process. The oxyacetylene torch is another important industrial application. Oxygen is utilized in medicine in the treatment of respiratory diseases and is mixed with other gases for respiration in submarines, high-flying aircraft, and spacecraft.
Most people know that helium is used as a lifting gas in blimps and party balloons, but they can't name another way in which it is used. The number one use of helium is as a cooling gas for magnetic resonance imaging (MRI) machines used in medical facilities. Other important uses of helium include: a protective gas for welding, an inert gas for controlled atmosphere manufacturing, a fugitive gas used for leak detection, and a low-viscosity gas for pressurized breathing mixtures.