Editing Test tube (section)

==Types and usage==

[[File:Louis Lumiere with microscope and test tubes.jpg|thumb|240px|right|[[Louis Lumière]] with a [[microscope]] and some test tubes]]

===Chemistry===

Test tubes intended for general chemical work are usually made of glass, for its relative resistance to heat. Tubes made from expansion-resistant glasses, mostly [[borosilicate glass]] or [[fused quartz]], can withstand high temperatures up to several hundred degrees [[Celsius]].

Chemistry tubes are available in a multitude of lengths and widths, typically from 10 to 20&nbsp;mm wide and 50 to 200&nbsp;mm long.<ref>{{Cite web |title=Test Tube, culture tube, disposable tube |url=http://catalog.miniscience.com/catalog/Glassware/Test_Tube.html |url-status=dead |archive-url=https://web.archive.org/web/20060518135424/http://catalog.miniscience.com/catalog/Glassware/Test_Tube.html |archive-date=2006-05-18 |website=MiniScience.com}}</ref> The top often features a flared lip to aid pouring out the contents.

A chemistry test tube typically has a flat bottom, a round bottom, or a conical bottom. Some test tubes are made to accept a [[ground glass joint|ground glass stopper]] or a [[screw cap]].  They are often provided with a small [[ground glass]] or white [[glaze (pottery)|glaze]] area near the top for labelling with a pencil.

Test tubes are widely used by [[chemist]]s to handle chemicals, especially for qualitative experiments and assays. Their spherical bottom and vertical sides reduce mass loss when pouring, make them easier to wash out, and allow convenient monitoring of the contents.  The long, narrow neck of test tube slows down the spreading of gases to the environment.

Test tubes are convenient containers for heating small amounts of liquids or solids with a [[Bunsen burner]] or [[alcohol burner]]. The tube is usually held by its neck with a [[clamp (tool)|clamp]] or [[tongs]].  By tilting the tube, the bottom can be heated to hundreds of degrees in the flame, while the neck remains relatively cool, possibly allowing vapours to condense on its walls. A [[boiling tube]] is a large test tube intended specifically for boiling liquids.

A test tube filled with water and upturned into a water-filled [[Beaker (glassware)|beaker]] is often used to capture [[gas]]es, e.g. in [[electrolysis]] demonstrations.

A test tube with a [[stopper (plug)|stopper]] is often used for temporary storage of chemical or biological samples.[[File:Blood test.jpg|right|240px|thumb|Samples of human blood collected for [[blood test]]s]]

===Biosciences===
Culture tubes are test tubes used in [[biology]] and related sciences for handling and culturing all kinds of live [[organisms]], such as [[Mold (fungus)|molds]], [[bacteria]], [[seedling]]s, [[cutting (plant)|plant cutting]]s, etc..  Some racks for culture tubes are designed to hold the tubes in a nearly horizontal position, so as to maximize the surface of the [[culture medium]] inside.

Culture tubes for biology are usually made of clear plastic (such as [[polystyrene]] or [[polypropylene]]) by [[injection molding]]<ref>{{cite book |author1=M. Jeremy Ashcraft |author2=General Manager |author3=Lake Charles Manufacturing | title=Test Tube Molding Process: A discussion on the molding of plastic test tubes |publisher=Lake Charles Manufacturing |year=2007}}</ref> and are often discarded after use. Plastic test tubes with a screwtop cap are often called "Falcon tubes" after a line manufactured by [[Becton Dickinson]].<ref name="BD Falcon Tubes and Pipets">{{cite web |title=BD Falcon Tubes and Pipets |url=https://www.bdbiosciences.com/documents/tube_pipet_brochure.pdf |publisher=[[Becton Dickinson]] |access-date=14 March 2016}}</ref>

Some sources consider that the presence of a lip is what distinguishes a test tube from a culture tube.<ref>Thomas Scott (transl., 1996), ''Concise Encyclopedia: Biology''. Walter de Gruyter. {{ISBN|3-11-010661-2}}, {{ISBN|978-3-11-010661-9}}. 1287 pages.</ref>

===Clinical medicine===
In clinical medicine, sterile test tubes with air removed, called [[vacutainer]]s, are used to collect and hold [[biological specimen|samples of physiological fluids]] such as [[blood]], [[urine]], [[pus]], and [[synovial fluid]].  These tubes are commonly sealed with a rubber stopper and often have a specific additive placed in the tube with the stopper color indicating the additive.  For example, a ''blue-top tube'' is a 5&nbsp;[[milliliter|ml]] test tube containing [[Trisodium citrate|sodium citrate]] as an anticoagulant, used to collect blood for [[coagulation screen|coagulation]] and [[glucose-6-phosphate dehydrogenase]] testing.<ref>[http://medical-dictionary.thefreedictionary.com/blue+top+tube TheFreeDictionary > blue top tube]. Citing: McGraw-Hill Concise Dictionary of Modern Medicine. 2002 by The McGraw-Hill Companies, Inc.</ref> Small [[vial]]s used in medicine may have a snap-top (also called a hinge cap) molded as part of the vial.
{{Table of blood sampling tubes}}

===Other uses===

Test tubes are sometimes put to casual uses outside of lab environments, e.g. as [[flower vase]]s, glassware for certain weak [[shooter (mixed drink)|shots]], or containers for [[spice]]s. They can also be used for raising queen ants during their first months of development.