Watch glass

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Caesium fluoride sample on a watch glass
A watch glass is a circular, slightly piece of glass used in chemistry as a surface to evaporate a liquid, to hold solids while being weighed, or as a cover for a beaker. The latter use is generally applied to prevent dust or other particles entering the beaker; the watch glass does not completely seal the beaker, and so gas exchanges still occur.

When used as an evaporation surface, a watch glass allows closer observation of precipitates or crystallisation, and can be placed on a surface of contrasting colour to improve the visibility overall.

Watch glasses are so named because they are identical to the glass used for the front of old-fashioned pocket watches. In reference to this, large watch glasses are occasionally known as clock glasses.




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Evaporation is the process by which molecules in a liquid state (e.g. water) spontaneously become gaseous (e.g. water vapor), without being heated to boiling point. It is the opposite of condensation.
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A beaker is a simple container for liquids, very commonly used in laboratories. Beakers are generally cylindrical in shape, with a flat bottom. Beakers are available in a wide range of sizes, from 1mL up to several litres.
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Precipitation is the formation of a solid in a solution during a chemical reaction. When the chemical reaction occurs the solid formed is called the precipitate. This can occur when an insoluble substance, the precipitate
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Crystallization is the (natural or artificial) process of formation of solid crystals from a uniform solution. Crystallization is also a chemical solid-liquid separation technique, in which mass transfer of a solute from the liquid solution to a pure solid crystalline phase occurs.
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agar plate is a sterile Petri dish that contains a growth medium (typically agar plus nutrients) used to culture microorganisms. Selective growth compounds may also be added to the media, such as antibiotics.
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aspirator, also called an ejector or filter pump, is a device that produces vacuum by means of the Venturi effect. In an aspirator, fluid (liquid or gaseous) flows through a tube which then narrows.
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autoclave is a pressurized device designed to heat aqueous solutions above their boiling point to achieve sterilization. It was invented by Charles Chamberland in 1879.[1] The term autoclave
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Bunsen burner is a common piece of laboratory equipment used for heating, sterilization, and combustion.

History

A common misconception is that the Bunsen burner was invented by German chemist Robert Wilhelm Bunsen and Christian Schonbein.
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calorimeter is a device used for calorimetry, the science of measuring the heat of chemical reactions or physical changes as well as heat capacity. The word calorimeter is derived from the Latin word calor, meaning heat.
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colony counter is an instrument used to count colonies of bacteria or other microorganisms growing on an agar plate. Early counters were merely lighted surfaces on which the plate was placed, with the colonies marked off with a felt-tipped pen on the outer surface of the plate
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colorimeter is an instrument for determining the concentration of a particular compound in a preparation by comparing the intensity of colour in it with that of a standard (control) preparation of known concentration. This device used for colorimetry was invented by Jan Szczepanik.
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laboratory centrifuge is a piece of laboratory equipment, driven by a motor, which spins liquid samples at high speed. There are two main sizes for laboratory centrifuges. The larger ones are known simply as centrifuges; samples are contained in centrifuge tips or
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fume hood or fume cupboard is a large piece of scientific equipment common to chemistry laboratories designed to limit a person's exposure to hazardous fumes. Fume hoods were originally manufactured from timber, but now epoxy coated mild steel is the main construction
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glovebox, also called a glove box, is a sealed container that is designed to allow one to manipulate objects while being in a different atmosphere from the object. Built into the sides of the glovebox are two gloves arranged in such a way that one can place his or her hands
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In microbiology, an incubator is a device for controlling the temperature, humidity, and other conditions in which a microbiological culture is being grown. The simplest incubators are insulated boxes with an adjustable heater, typically going up to 60 to 65 °C (140 to 150 °F),
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A laboratory equipment for the homogenization of various types of material, such as tissue, plant, food, soil, and many others. Many different models have been developed using various physical technologies for the disruption.
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Laminar flow cabinet or laminar flow closet is a carefully enclosed bench designed to prevent contamination of semiconductor wafers, biological samples, or any particle sensitive device.
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magnetic stirrer is a type of laboratory equipment consisting of a rotating magnet or stationary electomagnets creating a rotating magnetic field. The stirrer is used to cause a stir bar, immersed in a liquid to be stirred, to spin very quickly, stirring it.
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A Microtiter plate or microplate is a flat plate with multiple "wells" used as small test tubes. The microplate has become a standard tool in analytical research and clinical diagnostic testing laboratories.
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Microplate Readers (also known as Plate readers) are laboratory instruments designed to detect biological, chemical or physical events of samples in microtiter plates. Sample reactions can be (assayed) in 6-1536 well format microtiter plates.
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In physics, spectrophotometry is the quantitative study of electromagnetic spectra. It is more specific than the general term electromagnetic spectroscopy in that spectrophotometry deals with visible light, near-ultraviolet, and near-infrared.
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stir bar (or flea) is a magnetic bar, used to stir a liquids in a laboratory. The stir bar rotates (and thus stirs) in synch with a separate rotating magnet located beneath the vessel containing the reaction.
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contradict the article Timeline of temperature and pressure measurement technology. Please see discussion on the linked talk page.
A thermometer is a device that measures temperature or temperature gradient, using a variety of different principles.
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vortex mixer is a simple device used commonly in laboratories to mix small vials of liquid. It consists of an electric motor with the drive shaft oriented vertically and attached to a cupped rubber piece mounted slightly off-center.
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static mixer is a device for blending (mixing) two liquid materials. The device consists of mixer elements contained in a cylindrical (tube)or squared housing. The static mixer elements consist of a series of baffles that are made from metal or a variety of plastics.
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Laboratory glassware refers to a variety of equipment, traditionally made of glass, used for scientific experiments and other work in science, especially in chemistry and biology laboratories.
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A beaker is a simple container for liquids, very commonly used in laboratories. Beakers are generally cylindrical in shape, with a flat bottom. Beakers are available in a wide range of sizes, from 1mL up to several litres.
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A boiling tube is a large cylindrical vessel used to strongly heat substances in the flame of a Bunsen burner. A boiling tube is essentially a scaled-up test tube, being about 50% larger in every aspect.
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