used to chemical test
this is a laboratory apparatus, usually use in holding substances. for example test tube...
apparatus
Container of liquid/chemical
condenser
crucible tong iron stand iron ring Bunsen burner
beaker crucible watch glassmortar and pestle evaporating dish plastic pipetfunnel ring stand erlenmeyer flaskrubber stopper pH paper test tube holderclay triangle crucible tongs scoopulabunsen burner test tube brush beaker tongsthermometer wire gauze innoculating looptest tube rack buret graduated cylindertest tube clamp ring clamp triple beam balanceforceps buret clamp stirring rodgoggles filter paper test tubewell plate lab apron strikerrubber tubing glass plate weighing boatlitmus paper wooden splint volumetric flaskelectronic balance dropper bottle
the answer is none
This really isn't something that requires an instruction manual ― it's a cork. You place it in a test tube if you intend on shaking the contents. How do you use it? Again...not a complicated process. Fit it inside the test tube.
A test tube rack.
Test Tube brushes are used to easily clean the test tubes .
A test tube holder or rack is used in a laboratory to hold or support test tubes containing chemicals or other contents awaiting further operations. Although it is called a test tube holder, it is also used to hold/support pipettes, etc. Since a test tube has a rounded bottom, it cannot stand by itself; the rack is a convenient and necessary piece of laboratory equipment for the storage of test tubes.
examples of porcelain laboratory apparatus