Distillation Apparatus

Quick Answer: A laboratory distillation apparatus is a glass set-up that boils a liquid mixture, carries the vapour through a condenser and collects the condensed liquid in a receiver. It is used to purify liquids and to separate a liquid from dissolved solids or from other liquids with a different boiling point.

The Parts and What Each Does

Every distillation set, whatever its size, follows the same path. A boiling flask holds the mixture over a heat source. A still head or side-arm neck turns the vapour sideways, and a thermometer placed at that outlet records the temperature of the vapour actually leaving. A water-cooled condenser, sloping downwards, turns the vapour back into liquid, and an adapter guides the distillate into a receiving flask.

In jointed glassware these pieces connect through ground glass cones and sockets, which lets the same parts be rearranged for other techniques; older teaching sets join them with bored corks or rubber bungs. The listing is titled simply Distillation Apparatus and does not state which pieces, joint sizes or flask capacity are included, so agree the parts list before ordering.

LabEquip also lists more specialised set-ups: the simple type distillation assembly for introductory practicals and the vacuum distillation assembly for high-boiling or heat-sensitive liquids.

Specifications

Principle	Separation by differences in boiling point
Typical components	Boiling flask, still head or side arm, thermometer, condenser, adapter, receiver
Connections	Ground glass joints or bungs, depending on the set
Heat source	Heating mantle, water bath or sand bath, according to the liquid
Parts list, joint size and capacity	Confirm at enquiry

Applications

Preparing distilled water from tap water in a practical on purification
Separating ethanol from a fermented sugar solution and testing the distillate
Recovering a solvent such as ethanol after an extraction
Finding the boiling range of an unknown liquid as a check on its purity

Care & Handling

Drop anti-bumping granules into the mixture while it is still cold; adding them to hot liquid can set off sudden boiling.
Never heat a closed system: the receiver end must remain open to the air.
Fill the boiling flask no more than about two-thirds full and never distil to dryness.
Clamp the flask neck and the condenser separately so that no joint carries a strained load.

Why Choose LabEquip

Schools, colleges and polytechnics usually want one distillation set per bench group, with spare condensers and flasks. LabEquip supplies laboratory distillation apparatus as part of its chemistry lab equipment; agree the parts list and quantities through the contact page.

Frequently Asked Questions

What is the difference between simple and fractional distillation?

Simple distillation passes vapour straight from the flask to the condenser and works when boiling points are far apart or when a liquid is separated from dissolved solids. Fractional distillation adds a packed or indented column that gives repeated condensation and re-evaporation, separating liquids with close boiling points.

Why does the thermometer reading stay steady during distillation?

While a pure substance is distilling, the vapour reaching the bulb is at that liquid’s boiling point, so the reading holds constant. A rise in temperature signals that the first component has largely distilled over and the next is starting.

Which heat source is safest?

A heating mantle or water bath is preferred for flammable liquids such as ethanol, because there is no open flame. A Bunsen burner and gauze is acceptable only for water and other non-flammable aqueous mixtures.

Why should the flask not be distilled to dryness?

The last residue can overheat and decompose, and the flask may crack when no liquid is left to take up the heat. With some solvents, such as ethers, concentrated residues can contain unstable peroxides.

How pure is the distillate from a simple set-up?

Separation of a liquid from dissolved salts is essentially complete, since the salts do not evaporate. Two liquids with similar boiling points are only partly separated in a single simple distillation, and the distillate still contains some of each.

Can the same apparatus be used for reflux?

With jointed glassware, yes: the condenser is moved to a vertical position directly above the flask, so vapour returns to the flask instead of passing to a receiver. Sets joined with bungs are less easy to rearrange.

Last Updated: September 2026

Desiccator, Clear Glass

Quick Answer: A clear glass desiccator is a transparent, lidded glass container with a lower compartment for a drying agent and a plate above it for samples. It gives school and college laboratories a simple way to keep hygroscopic chemicals, dried samples and small apparatus in dry air at room temperature.

Keeping Water Out of Chemicals That Attract It

Many laboratory chemicals take up water from the air. Sodium hydroxide pellets turn wet and sticky, anhydrous copper(II) sulfate turns blue, and calcium chloride can eventually dissolve in the water it absorbs. Once that happens, a weighed amount no longer contains the quantity of substance a student expects. A desiccator slows this down by holding the containers over a drying agent, which soaks up the water vapour that enters each time the lid is opened.

The transparent wall lets a teacher see at a glance what is stored and whether the indicating silica gel has changed colour, without opening the lid and letting moist air in. The listing specifies clear glass without saying which kind; in catalogues that wording usually signals the soda-lime alternative to borosilicate, which is well suited to room-temperature storage but less tolerant of hot items.

For cooling crucibles straight after heating in gravimetric work, the borosilicate glass desiccator is the better match. Plate diameter and lid type are not given in the listing.

Applications

Storing deliquescent reagents such as sodium hydroxide pellets and calcium chloride between practicals
Keeping dried filter papers, weighing boats and small samples dry before weighing
Holding dried plant or soil samples for biology and geography projects before they are weighed
Protecting moisture-sensitive indicator papers and test strips in the prep room

Specifications

Item	Glass desiccator with ground lid, plate and desiccant compartment
Material	Clear glass; composition not stated in the listing
Intended use	Dry storage at room temperature
Seal	Greased ground flange between lid and body
Size and lid type	Confirm at enquiry

Care & Handling

Allow anything warm to cool to room temperature before it goes inside.
Slide the lid on and off, and keep a folded cloth under the base so the desiccator cannot slip on a wet bench.
Change or dry the desiccant regularly, since exhausted silica gel does nothing to protect the contents.
Label containers inside and keep the plate free of spilled powder, which can reach and contaminate the desiccant.

Why Choose LabEquip

Schools and colleges that need dependable dry storage for a handful of reagents often choose a clear glass desiccator as the practical, visible option. It sits in LabEquip’s chemistry lab equipment category, and quantities or a preferred size can be sent via the contact page.

Frequently Asked Questions

What is the difference between a desiccator and an airtight jar?

An airtight jar only stops more moist air getting in. A desiccator also contains a drying agent that removes the water vapour already inside and the vapour that enters when the lid is opened, so the air around the samples stays dry.

Is the clear glass version suitable for hot crucibles?

It is better kept for room-temperature storage. If your work involves cooling crucibles after heating, choose borosilicate glass, which tolerates warm items with much less risk of cracking.

How do I know when the silica gel needs changing?

Self-indicating silica gel changes colour as it absorbs water, typically from blue to pink or from orange to green depending on the indicator used. Once most of it has changed, dry it in an oven and let it cool in a closed container before reuse.

Where should the drying agent go?

In the lower compartment, below the perforated plate. Spread it in an even layer and keep it well below the plate so it never touches the samples or their containers.

Why do students struggle to open the lid?

The flange is greased to seal, and the lid is meant to slide off sideways, not lift. Show students how to hold the base firmly and push the lid across with the palm of the hand.

Can I store chemicals in open dishes inside?

Keep them in their own labelled, loosely capped containers. Open dishes of volatile or reactive chemicals can contaminate the desiccant and react with each other’s vapours.

Last Updated: September 2026

Desiccator, Borosilicate Glass

Quick Answer: A borosilicate glass desiccator is a heavy glass vessel with a ground-flanged lid and a perforated plate above a lower chamber that holds a drying agent. It keeps samples in dry air, most often so that heated crucibles and weighing bottles can cool without absorbing moisture before they are weighed.

Cooling to Constant Mass

In gravimetric analysis a crucible or precipitate is heated, cooled and weighed repeatedly until two weighings agree. Cooling in open air would let a hot, dry sample pick up water vapour, so the cooling step takes place in a desiccator. The drying agent in the lower chamber, commonly self-indicating silica gel or anhydrous calcium chloride, keeps the enclosed air dry, and a perforated plate, usually porcelain, supports the crucibles above it.

The lid seals on a ground glass flange that is lightly greased, and it is opened by sliding it sideways rather than lifting it. Borosilicate glass copes better than ordinary soda-lime glass with warm crucibles set on the plate and with changes in room temperature, which is why it is preferred for regular analytical use. It is still not meant for red-hot items: let crucibles cool briefly on a heat-resistant tile before transferring them.

The listing does not say whether the lid carries a stopcock for evacuation, nor the plate diameter. A plain lid is used at atmospheric pressure; a vacuum lid allows faster drying. See the clear glass desiccator for general storage, and the plastic vacuum desiccator when breakage is the bigger concern.

Specifications

Item	Desiccator with lid, lower desiccant chamber and plate support
Material	Borosilicate glass, per the listing title
Lid seal	Ground flange, sealed with a thin film of grease
Plate	Perforated support plate, commonly porcelain
Lid type and diameter	Confirm at enquiry

Applications

Cooling crucibles, weighing bottles and filter crucibles between heating and weighing in gravimetric work
Holding oven-dried primary standards, such as anhydrous sodium carbonate, until they are weighed for standard solutions
Storing dried soil, cement or plant samples before moisture-content determination
Keeping anhydrous salts from absorbing water between practicals

Care & Handling

Open by sliding the lid horizontally; lifting a greased lid straight up rarely works and risks dropping it.
Regrease the flange sparingly when the lid starts to catch, wiping off old grease first so grit does not scratch the seal.
Replace or regenerate the silica gel when its indicator changes colour, and keep desiccant off the plate.
Carry a loaded desiccator with both hands and a thumb on the lid, never by the knob alone.

Why Choose LabEquip

Analytical, pharmacy and soil-testing laboratories that weigh to constant mass every day need a desiccator that tolerates warm crucibles. LabEquip lists it among its chemistry lab equipment; give the diameter and lid type you need through the contact page.

Frequently Asked Questions

Why must crucibles be cooled in a desiccator before weighing?

A hot crucible cooling in room air takes up water vapour on its surface, and a warm object also disturbs a balance through air currents. Cooling in dry, enclosed air to room temperature gives a reliable, repeatable mass.

Which drying agent should I use?

Self-indicating silica gel is the most common choice because it shows when it is exhausted and can be regenerated in an oven. Anhydrous calcium chloride is cheap for general storage. Stronger desiccants such as phosphorus pentoxide are reserved for special work.

How do I open a desiccator lid that has stuck?

Push the lid sideways with steady pressure on the knob while holding the base. If it does not move, warm the flange gently with a warm cloth to soften the grease. Never lever the lid off with a tool.

Can I put a red-hot crucible straight into the desiccator?

No. Let it cool in the air for a short time on a heat-resistant tile first. Very hot objects can crack the plate or the glass, and they heat the enclosed air, which then contracts and can make the lid hard to open.

How is borosilicate better than clear glass for a desiccator?

Borosilicate glass expands much less when heated, so it tolerates warm crucibles and changes in room temperature with less risk of cracking. For storing chemicals at room temperature the difference matters less.

What grease should be used on the flange?

Use a laboratory stopcock or vacuum grease, applied as a thin, even film. Too much grease lets the lid slide off and collects dust; too little leaves a leaky seal.

Last Updated: September 2026

Condenser for Soxhlet Apparatus, Allihn

Quick Answer: A Soxhlet condenser of the Allihn type is a water-jacketed bulb condenser that fits on top of a Soxhlet extractor. It turns the solvent vapour rising from the boiling flask back into liquid, which drips onto the sample thimble and drives each extraction cycle.

Where the Condenser Sits in a Soxhlet Set

A Soxhlet set is built as a vertical stack: a boiling flask at the bottom, the extractor body holding the thimble in the middle, and the condenser on top. Solvent vapour travels up the extractor’s side tube, passes the thimble chamber and enters the condenser, where the cooled bulbs turn it back into liquid. The condensate falls onto the sample, fills the chamber and eventually siphons back to the flask, carrying extracted material with it.

The condenser therefore sets a limit on how fast the cycles can run. If it is too small or the water too warm, vapour escapes from the top, solvent is lost and the chamber fills slowly. Allihn bulbs create a large cooling surface in a compact height, which suits the tall assembly, and because the condensate drips straight down from the lowest bulb, bulbs cause no drainage problem in this upright position.

This listing is the condenser made for the Soxhlet extractor, as distinct from the general-purpose Allihn condenser used for reflux on a flask. The practical difference is the joint at its lower end, which must match the socket at the top of the extractor; on many Soxhlet sets that socket is wider than the joint on the flask. The listing does not give the joint size or jacket length, so quote the extractor size when ordering the condenser separately from a complete Soxhlet extraction apparatus.

Applications

Continuous extraction of fat from ground seeds, snacks or feeds with petroleum ether or hexane
Extracting chlorophyll and other leaf pigments for chromatography practicals
Removing caffeine from tea leaves in organic chemistry teaching
Replacing a broken condenser on an existing Soxhlet set of the same joint size

Specifications

Item	Allihn (bulb) condenser for fitting on a Soxhlet extractor
Cooling	Water jacket around a chain of bulbs
Position	Vertical, at the top of the Soxhlet stack
Coolant connections	Inlet low, outlet high, joined with rubber or silicone tubing
Lower joint and jacket length	Confirm at enquiry, to match the extractor

Care & Handling

Start the cooling water before switching on the heat, and leave it on until the flask is cool.
Secure the condenser with its own clamp; the joint alone should not carry its weight at the top of a tall stack.
If vapour reaches the upper bulbs, reduce the heat rather than turning the water up so hard that the tubing blows off.
Wipe solvent residue off the joint and store the condenser lying flat in a padded drawer.

Why Choose LabEquip

Food testing, oilseed and agriculture laboratories that run Soxhlet extractions for hours at a time need a condenser that keeps pace with continuous boiling. Order it alongside other chemistry lab equipment from LabEquip, quoting the extractor capacity and joint size on the contact page.

Frequently Asked Questions

Can I use any Allihn condenser on a Soxhlet extractor?

Only if its lower joint matches the socket at the top of the extractor. General reflux condensers are often made with a smaller cone for flasks, so a condenser sold for Soxhlet use saves adapters and keeps the stack shorter.

How fast should the Soxhlet cycles run?

Methods usually aim for several siphon cycles per hour, set by the heating rate. The condenser must return all the vapour at that rate; if solvent odour is noticeable at the top, lower the heat until condensation stays in the lower bulbs.

Is a coil condenser better than an Allihn for Soxhlet work?

Both are used. An Allihn is easy to clean and drains freely when vertical, which makes it a common choice; a coil condenser of the Dimroth type packs more cooling into the same height and helps with very volatile solvents such as diethyl ether.

Should the top of the condenser be closed?

No. The system must stay open to the air so pressure cannot build up. If moisture has to be excluded, fit a drying tube packed with a desiccant rather than a stopper.

What solvents are commonly used in a Soxhlet extraction?

Petroleum ether and hexane are usual for fats and oils, ethanol or methanol for more polar compounds. Choose a solvent that dissolves the target compound but leaves most of the sample matrix behind, and heat flammable solvents on a mantle or water bath, never a flame.

Why does solvent collect in the condenser instead of dripping down?

A few drops held in the bulbs is normal. Flooding, where liquid is pushed upward by vapour, means the heat is too high for the condenser; reduce the heating rate until the condensate falls back freely.

Last Updated: September 2026

Centrifuge Tube, Glass

Quick Answer: The Centrifuge Tube, Glass is a thick-walled glass tube that holds liquid samples while they are spun in a centrifuge. A glass centrifuge tube is chosen when the sample contains solvents that attack plastic or when tubes are to be washed and reused.

When to Choose Glass for Centrifugation

In a centrifuge, denser particles are driven to the bottom of the tube, forming a pellet, while the lighter liquid above, the supernatant, can be poured or pipetted off. Glass tubes are chosen over plastic for work with organic solvents such as chloroform, phenol, acetone and ether, which soften or dissolve many plastics. They can be washed, dried and sterilised repeatedly, and liquid levels and pellets are easy to see through the clear wall.

Glass has limits. It tolerates much lower centrifugal force than many plastic tubes, so it belongs in bench and clinical centrifuges at moderate speeds rather than high-speed rotors, and each tube’s rating should be known before use. Rubber cushions in the buckets help to spread the load. Tubes must be balanced in opposite positions, and any tube with a chip or crack should be discarded, because it can shatter under load.

Tubes of this kind are commonly made with a conical bottom that gathers a small pellet in the tip, graduated or plain; the listing does not state the bottom shape, graduation or capacity. A graduated glass centrifuge tube is listed separately for volume readings.

Specifications

Item	Centrifuge tube, glass
Main advantage	Resists organic solvents; reusable after washing
Limitation	Lower g-force tolerance than many plastic tubes
Accessories	Rubber cushions or adapters for the centrifuge buckets
Bottom shape, graduation, capacity and speed rating	Confirm at enquiry

Applications

Preparing urine sediment for microscopy in a laboratory centrifuge during clinical pathology practicals
Separating precipitates from solutions in chemistry and biochemistry
Phenol-chloroform extraction and other solvent work in molecular biology
Harvesting cells or microbes from broth cultures

Safe Centrifugation

Inspect each glass centrifuge tube against the light for chips, scratches and star cracks before every run.
Load tubes in opposite positions with equal volumes, and use cushions or adapters that fit the tube.
Stay within the tube’s rated speed and let the rotor stop on its own before opening the lid.
If a tube breaks, switch off, wait for the rotor to stop and clean the bucket with care, disinfecting it if the sample was biological.

Why Choose LabEquip

Clinical pathology labs, biochemistry teaching labs and chemistry departments keep glass centrifuge tubes for solvent work and for tests where tubes are reused. LabEquip lists them in Biology Lab Products; tell us the capacity and bottom shape you need through the contact page.

Frequently Asked Questions

When should I use glass instead of plastic tubes?

Use glass for organic solvents such as chloroform, phenol or ether that attack many plastics, and when tubes are to be washed and reused. Use plastic for high-speed runs.

How fast can a glass tube be spun?

Glass withstands much less centrifugal force than most plastic tubes, so it is used at moderate speeds in bench centrifuges. Know the tube’s rating and your rotor’s limits before each run.

Why are centrifuge tubes balanced?

An unbalanced rotor vibrates heavily, which can damage the centrifuge and break tubes. Tubes of equal mass must be placed directly opposite each other.

What is the conical bottom for?

A conical tip collects the pellet into a small area, making it easy to see and to remove the supernatant without disturbing it.

How should the tubes be cleaned?

Rinse promptly, soak in laboratory detergent, scrub gently with a soft tube brush so the inside is not scratched, rinse with distilled water and dry. Scratches weaken the glass under load.

What capacity and bottom shape do these tubes have?

Glass centrifuge tubes are made in several capacities, with conical or round bottoms and with or without graduations. The listing does not specify these, so confirm them when you enquire.

Last Updated: September 2026

Buchner Funnels, Porcelain, With Sintered Disc

Quick Answer: A porcelain Buchner funnel with sintered disc is a white ceramic suction-filtration funnel whose filter plate is a porous, fused ceramic disc instead of a perforated plate covered with paper. It is used on a filtering flask to separate solids from liquids, particularly hot or chemically aggressive mixtures.

Ceramic Body, Porous Plate

Porcelain has long been the traditional material for Buchner funnels because it is rigid, copes well with heat and resists most acids. The version described here replaces the usual pattern of holes with a porous plate made by sintering ceramic particles, so the plate itself retains the solid. Suction from below draws the liquid through the pores, and the solid collects as an even cake across the plate.

Compared with a sintered glass funnel, porcelain is opaque, so the condition of the plate can only be judged from above. It is heavier, stands up well to the knocks of a busy washing-up area, and glazed porcelain handles hot filtrations comfortably. Like glass, it is attacked by hydrofluoric acid and by hot concentrated alkalis, which dissolve the glaze and open up the pores.

Porcelain Buchner funnels are also widely sold with a perforated plate for use with paper, under very similar names. The title here says sintered disc, but confirm the plate type, porosity and diameter when ordering, especially if your method was written for paper. The sintered glass Buchner funnel is the transparent alternative, and either funnel fits a filtering flask on a rubber cone or bung.

Care & Handling

Warm the funnel before a hot filtration and cool it slowly afterwards; porcelain resists heat but can crack if a cold funnel meets boiling liquid.
After use, draw water through from below as well as from above to flush particles out of the pores.
Soak stubborn inorganic deposits in dilute hydrochloric acid, then rinse thoroughly before drying.
Check the rim and stem for chips before fitting the funnel, because a chip can break the vacuum seal.

Applications

Hot suction filtration of mixtures that would crystallise on a cold funnel, with the porcelain pre-warmed in an oven
Collecting inorganic precipitates and washing them free of soluble salts
Separating solids from acidic leach solutions in materials and mineral laboratories
Dewatering filter cakes of pigments, clays or soil samples in student projects

Specifications

Item	Buchner-type suction funnel in porcelain
Filter plate	Porous sintered ceramic disc, per the listing title
Heat (general)	Porcelain tolerates hot filtrations and oven drying; avoid sudden temperature shocks
Chemical limits (general)	Not for hydrofluoric acid or hot concentrated alkali
Plate type, porosity and diameter	Confirm at enquiry

Why Choose LabEquip

Materials, mineral and inorganic chemistry labs often choose porcelain where funnels face heat and heavy daily use. LabEquip lists this funnel in its chemistry lab equipment collection; tell us the plate type and diameter your procedure needs through the contact page.

Frequently Asked Questions

How is a sintered porcelain plate different from a perforated one?

A perforated plate has visible holes and needs a filter paper laid over it to catch the solid. A sintered plate is itself porous, so the solid is retained on the ceramic surface and no paper is required.

Is porcelain or sintered glass better for my filtration?

Glass lets you see the disc and is easier to inspect for blockage. Porcelain is opaque but rugged and handles hot mixtures well. Both are attacked by hydrofluoric acid and hot alkali, so the choice usually comes down to visibility versus robustness.

How should the funnel be sealed to the flask?

Use a rubber cone or a bored bung that fits the stem snugly and sits in the flask neck. Moisten the rubber slightly to seat it. A leak at this joint is the most common reason for weak suction.

Can I put the funnel in a drying oven?

Yes, porcelain tolerates oven drying well. Let it cool in the oven or on a heat-resistant mat rather than rinsing it while hot, because sudden cooling is what cracks ceramic ware.

Why does the filtrate come through cloudy at first?

The first portion may carry very fine particles that pass the pores before a cake forms. Pour the cloudy filtrate back through once a thin layer of solid has built up on the plate; the cake then acts as an extra filter.

How do I remove a precipitate that has lodged in the pores?

Choose a solvent or dilute acid that dissolves it and pull it through the plate under gentle suction, then flush with water from the stem side. Avoid scraping the plate with metal tools, which can damage the surface.

Last Updated: September 2026

Buchner Funnels, Glass, With Sintered Disc

Quick Answer: A sintered glass Buchner funnel is a glass filter funnel with a porous disc of fused glass particles sealed in place of the usual perforated plate and filter paper. It is used for suction filtration of precipitates, crystals and liquids that would attack paper, seated on a filtering flask connected to a vacuum source.

A Filter Built into the Funnel

In a conventional Buchner funnel the solid is caught on a circle of filter paper laid over a perforated plate. Here the filtering layer is part of the funnel itself: a disc made by heating graded glass grains until they fuse at their points of contact, leaving a network of fine channels. Liquid drawn through by suction passes along those channels, while particles larger than the pores stay on top as a cake that can be washed and sucked dry on the disc.

Doing without paper matters in several situations. Strong acids, oxidising solutions such as potassium permanganate and hot concentrated reagents can weaken or char cellulose, while glass is unaffected by most of them. No paper fibres enter the filtrate or the product, and the same funnel can be cleaned and reused many times. Fritted discs are made in a series of porosity grades, from coarse ones that pass liquid quickly to fine ones that hold back very small crystals; the listing does not state which grade is supplied, so choose it by the particle size of your precipitate.

Seat the funnel in a filtering flask using a bored bung or conical rubber adapter, then connect the side arm to a water filter pump or vacuum line. The porcelain Buchner funnel with sintered disc is the opaque ceramic alternative; glass has the advantage that the disc can be inspected for clogging or for colour left by earlier samples.

Specifications

Item	Buchner-type filter funnel with a fused sintered glass disc
Filter medium	Porous glass frit; no filter paper needed
Use with	Filtering flask, rubber bung or adapter, vacuum source
Chemical limits (general)	Attacked by hydrofluoric acid, hot concentrated phosphoric acid and hot strong alkalis
Porosity grade and diameter	Confirm at enquiry

Applications

Collecting recrystallised organic products, such as aspirin or acetanilide, and washing them with cold solvent on the disc
Filtering solutions of potassium permanganate, chromic acid or other oxidising reagents that damage filter paper
Removing fine solids from reagents or solvents before use, without adding paper fibres
Isolating precipitates in teaching labs where the funnel is reused by successive groups

Care & Handling

Wet the disc with the solvent before pouring in the mixture, and apply suction gently at first so fine particles do not pack deep into the pores.
Clean straight after use by drawing through a solvent that dissolves the residue, then plenty of water; flushing from below clears pores better than rinsing from above.
Dry in an oven with gradual heating and cooling, never by putting a wet frit into a hot oven or over a flame, as uneven heating can crack the seal between disc and wall.
Do not scrape the disc with a metal spatula; lift the cake with a plastic or rubber-tipped tool.

Why Choose LabEquip

University organic labs, pharmacy colleges and quality control rooms that filter corrosive or oxidising mixtures tend to prefer a sintered glass Buchner funnel to paper. LabEquip supplies it within the chemistry lab equipment range; state the disc porosity and funnel size you need on the contact page.

Frequently Asked Questions

Do I still need filter paper with a sintered disc?

No. The fused glass disc is the filter medium. Some users lay a paper circle on top when a precipitate is very fine or gelatinous, simply to protect the pores from clogging, but it is not required for normal work.

Which porosity grade should I choose?

Match the grade to the particle size. Coarse grades filter quickly and suit large crystals, medium grades suit most recrystallised products, and fine grades hold back small precipitates but filter slowly. Grading systems differ, so compare the stated pore-size range rather than only the grade name.

How do I clean a clogged sintered disc?

Pull a solvent that dissolves the deposit through the disc, then water. Inorganic residues often respond to warm dilute hydrochloric acid, organic residues to a suitable solvent. Back-flushing from the stem side helps. Avoid hot strong alkali, which etches glass and enlarges the pores.

Can the funnel be heated or dried in an oven?

Yes, glass frits are routinely oven-dried, but raise and lower the temperature gradually. A sudden temperature change, or a wet frit placed straight into a hot oven, can crack the disc or its seal to the funnel wall.

Which chemicals should not be filtered through sintered glass?

Hydrofluoric acid, hot concentrated phosphoric acid and hot concentrated alkali solutions attack glass. For those, use a filter made of a resistant plastic. Most acids, oxidising agents and organic solvents are compatible at room temperature.

Why is filtration through the disc so slow?

Usually because fine particles have been drawn into the pores, or the grade is finer than the solid requires. Start with gentle suction, let a thin layer of solid build up before applying full vacuum, and clean the frit fully between uses so it does not gradually block.

Last Updated: September 2026

Automatic Electrically Heated All Glass Distillation Apparatus

Quick Answer: An automatic all glass distillation apparatus is an electrically heated water still in which the parts in contact with the water are glass, so the water touches no metal. It boils tap or pre-treated water and condenses the steam to give distilled water, with automatic features to control the process.

What Automatic Means on a Water Still

The title calls the apparatus automatic but does not list the features. On electrically heated glass stills the term commonly covers a constant-level device, which keeps the water in the boiler at the right height by feeding it from the condenser’s outgoing cooling water, and a cut-out that switches the heater off if the water supply fails or the boiler runs low. Together they let the still run with far less supervision, but which of these this model has should be confirmed.

All-glass construction is chosen where distilled water must not pick up metal ions from a copper or steel boiler, for example water for EDTA titrations, conductivity work or biological media. Glass is also easy to inspect, so scale, cracks and the water level are all visible. In stills of this type the heating element is sealed in glass or quartz, so the water meets no metal; the output, heater power and supply voltage are not given in the title.

For water of higher purity, the all quartz double distillation apparatus distils twice through quartz. For general supplies, a single all-glass stage suits most teaching and routine uses.

Applications

Distilled water for preparing reagents and standard solutions in college labs
Water for titrations and conductivity measurements where metal ions must be avoided
Final rinsing of volumetric glassware
Topping up water baths and humidifiers to limit scale

Specifications

Type	Electrically heated water still
Construction	All glass in contact with the water
Automatic features	Not listed in the title (commonly level control and a heater cut-out)
Services needed	Electrical supply, cooling water, drain
Output, heater rating and voltage	Confirm at enquiry

Care & Handling

Site the still on a firm bench within reach of a tap and a drain, and get cooling water running through the condenser before the heater goes on.
Descale the boiler and heater sheath regularly; scale insulates the heater and makes it run hot.
Throw away the opening run of water whenever the still has been descaled or has stood unused for some days.
Keep electrical connections dry and have the installation checked by a qualified electrician.

Why Choose LabEquip

Teaching institutions and routine testing labs that want metal-free distilled water on site buy an automatic glass still for routine supply. LabEquip lists it in its chemistry lab equipment range; describe your daily water need and electrical supply on the contact page.

Frequently Asked Questions

What does automatic mean on this still?

It usually means the still keeps its own water level and switches off the heater if the water supply fails or the boiler runs low. The exact features of this model are not listed in the title.

Why choose an all-glass still instead of a metal one?

In an all-glass still the water touches only glass, so it picks up no copper, iron or other metal ions. That matters for titrations, conductivity work and biological media.

Is the distilled water pure enough for trace-metal analysis?

For routine work it usually is. For trace-metal analysis, water distilled twice in quartz, or further purified, is normally used.

How often should the still be descaled?

Whenever white scale builds up on the heater or boiler wall; with hard tap water that can be every few weeks. Softened or deionised feed water reduces scaling greatly.

What happens if the cooling water stops?

Steam is no longer condensed and the boiler level falls. A still with a water-failure cut-out switches the heater off; without one the heater can overheat, so such a still should never be left running unattended.

Why should the first distillate be discarded?

It rinses out anything left in the condenser and outlet after cleaning or standing idle. Collecting from the second portion onward gives water of consistent quality.

Last Updated: September 2026

Arsenic Apparatus

Quick Answer: An arsenic apparatus is a glass assembly used for the limit test for arsenic by the Gutzeit method. Arsenic in the sample is converted to arsine gas, which passes up a tube and stains a test paper impregnated with a mercuric salt; the stain is compared with one produced from a standard arsenic solution.

How the Gutzeit Test Works

The sample is dissolved in acid in the generator bottle or flask of the apparatus, and potassium iodide and stannous chloride are added to reduce any arsenic to the trivalent state. Zinc granules then generate hydrogen, which converts the arsenic to arsine gas. The gas rises through a glass tube packed with cotton wool moistened with lead acetate solution, which removes hydrogen sulfide that would otherwise darken the paper, and then meets mercuric chloride or mercuric bromide paper held across the top, depending on the pharmacopoeia followed. A yellow to brown stain forms in proportion to the arsenic present.

The result is a limit test, not a measurement. The stain from the sample is compared with that from a standard containing the permitted amount of arsenic, run at the same time in an identical apparatus. If the sample stain is no more intense than the standard, the sample passes. That is why arsenic apparatus is normally used in matched pairs.

Pharmacopoeias describe the apparatus in detail, including the bore of the tube and the way the paper is clamped, and the monograph being followed takes precedence. The listing title does not state which pattern this apparatus follows or which parts are included.

Care & Handling

Carry out the test in a fume cupboard: arsine is highly toxic, and the hydrogen generated by the zinc is flammable.
Handle mercuric salt papers with gloves, and dispose of used papers and lead acetate cotton as hazardous waste.
Use arsenic-free zinc and reagents, and run a blank if contamination is suspected; a stained blank shows the reagents are unsuitable.
Clean the apparatus with dilute acid and then distilled water after every test.

Applications

Limit test for arsenic in pharmaceutical raw materials in pharmacy college practicals
Quality control of chemicals and excipients against pharmacopoeial limits
Teaching qualitative trace analysis in analytical chemistry
Screening laboratory reagents for arsenic contamination

Specifications

Method	Gutzeit limit test for arsenic
Typical parts	Generator bottle, tube for lead acetate cotton, paper holder at the top
Detection	Mercuric chloride or mercuric bromide test paper
Material	Glass
Pattern and parts included	Confirm at enquiry

Why Choose LabEquip

Pharmacy colleges and pharmaceutical quality-control labs buy arsenic apparatus for limit tests, usually as a matched pair for sample and standard. LabEquip lists it with its chemistry lab equipment and within its wider range of pharmacy lab equipment; state the pattern you follow on the contact page.

Frequently Asked Questions

What is the Gutzeit test?

A limit test for arsenic in which arsenic in the sample is converted to arsine gas, which stains a mercuric salt test paper. The stain is compared with one from a standard arsenic solution.

Why is lead acetate cotton wool used in the tube?

It absorbs hydrogen sulfide, which can come from sulfur-containing samples or from the zinc and would also darken the test paper. Removing it prevents a false result.

Why are two apparatus needed?

The sample and the standard are run side by side under identical conditions. Matched apparatus means any difference in the stain comes from the arsenic content, not from the equipment.

Is the arsenic test dangerous?

Yes, if handled carelessly. Arsine is a highly toxic gas and the test papers contain mercury salts, so work in a fume cupboard, wear gloves and eye protection, and dispose of papers and residues as hazardous waste.

What does the stain colour mean?

A yellow to brown stain shows arsenic is present, and a deeper or longer stain means more of it. The sample passes the limit test if its stain is not more intense than the standard’s.

Why are stannous chloride and potassium iodide added?

They reduce arsenic in the higher oxidation state to the lower one, which the zinc and acid then convert to arsine quickly and completely, so sample and standard react in the same way.

Last Updated: September 2026

All Quartz Double Distillation Apparatus

Quick Answer: An all quartz double distillation apparatus is a laboratory water still in which the boiling vessels and condensers are made of fused quartz, and the water is distilled twice in succession. It produces distilled water with a very low content of dissolved solids for trace analysis and other purity-sensitive work.

Why Quartz, and Why Twice

A single distillation leaves most dissolved salts behind, but a little spray is carried over and some substances are picked up from the apparatus itself. Distilling the product a second time removes most of what the first stage let through. Building both stages from fused quartz, also called fused silica, deals with the other source: quartz is almost pure silicon dioxide and releases far less boron, sodium and other elements into hot water than borosilicate or soda-lime glass, which matters when the water is used for blanks and standards in trace-metal analysis.

Quartz also tolerates rapid temperature change and high temperature, which suits boilers that are heated directly. In the usual arrangement the distillate from the first stage feeds the second boiler, the doubly distilled water is collected from the second condenser, and cooling water passes through both condensers. The listing does not state the output rate, heater rating, electrical supply, cooling water demand or whether automatic cut-outs are fitted, and these should be confirmed before installation.

Even doubly distilled water takes up carbon dioxide from the air, which lowers its pH and raises its conductivity slightly on standing, so it should be stored in clean closed containers and used fresh for the most demanding work.

Specifications

Type	Double distillation water still
Wetted parts	Fused quartz boilers and condensers, as the title states
Heating	Electrical; heater details not stated in the title
Services needed	Electrical supply, cooling water, drain
Output, heater rating and safety cut-outs	Confirm at enquiry

Applications

Preparing blanks, standards and dilutions for trace-metal analysis
Water for conductivity measurements and sensitive electrochemistry
Research and pharmacy labs needing water free of glass-derived contaminants
Final rinsing of apparatus used for trace work

Care & Handling

Feed the still with softened or pre-treated water where possible, as hard tap water scales the boilers quickly.
Descale with a dilute acid suitable for quartz; never use hydrofluoric acid or hot strong alkali, which attack silica.
Never switch on the heaters with the boilers empty or the cooling water off.
Have the electrical installation and earthing checked by a qualified electrician before first use.

Why Choose LabEquip

Analytical, research and pharmacy laboratories that need very pure distilled water every day are the usual buyers of an all-quartz double still. LabEquip lists it with its chemistry lab equipment and also supplies the automatic all-glass distillation apparatus for general-purpose water; send your required output and installation details through the contact page.

Frequently Asked Questions

Why is quartz used instead of glass in a water still?

Fused quartz is nearly pure silica and releases far fewer trace elements into hot water than borosilicate or soda-lime glass. It also withstands sudden temperature changes.

What does double distillation achieve?

The water is distilled once, and that distillate is distilled again. The second stage removes most of the impurities carried over by spray or volatility in the first, giving a purer product.

Is double distilled water the same as deionised water?

No. Distillation removes dissolved salts and most non-volatile impurities, including most microorganisms and non-volatile organic matter. Deionisation removes ions efficiently but not uncharged organics, and many labs combine the two for the most demanding uses.

How should the distilled water be stored?

In clean, closed containers made of a material that does not leach into the water, filled fresh and used quickly. Water left open absorbs carbon dioxide from the air, which lowers its pH and raises its conductivity.

What services does the still need?

An electrical supply suited to the heaters, a continuous flow of cooling water for the condensers and a drain. The exact ratings are not stated in the title and should be confirmed before installation.

How often do the boilers need cleaning?

It depends on the feed water. With hard tap water, scale can appear within weeks; with softened or pre-purified feed water, cleaning is needed far less often. Descale whenever a white deposit forms.

Last Updated: September 2026