The Bunsen Burner

Robert Wilhelm Bunsen (1811-1899), a German chemist and inventor is credited with inventing the Bunsen burner, a gas burner used in scientific laboratories.

With Gustav R. Kirchhoff they pioneered work with spectrum analysis, inventing the spectroscope to detect chemicals by the colours they give off when burning. Using this instrument, they discovered the elements caesium (1860) and rubidium (1861).

Bunsen improved the efficiency of blast furnaces after observing gases escaping from them and devising a method of gas analysis. His other inventions include the ice calorimeter, a filter pump, a zinc-carbon electric cell, and the magnesium light. With Sir Henry Roscoe he did important work in the field of photochemistry.

The Bunsen Burner is used for heating chemicals, boiling water, sterilising small objects, preparing microscopic slides, bending glass tubing, and many other purposes.

The Bunsen burner consists of a straight metal tube, about five inches (13 cm) long, fastened to a stand. The bottom is connected by rubber tubing to a source of illuminating gas. Adjustable openings at the base of the burner admit air. The mixture of gas and air produces a very hot flame. Nozzles of various types can be fitted to the top of the burner to control the flame's shape.

Bunsen burner flames depend on air flow in the throat holes (on the burner side, not the needle valve for gas flow): 1. air hole closed (safety flame used for lighting or default), 2. air hole slightly open, 3. air hole half open, 4. hole almost fully open (roaring blue flame).

Flame Test

This is a method of detecting the presence of certain metals by the colours they give off in the flame of a Bunsen burner. A platinum or nichrome wire is dipped in a powder or solution of the compound to be tested, and the compound is then placed in the flame. Barium gives a green flame; calcium, orange; caesium, blue; copper, greenish blue; potassium, violet.

If more than one metal is present, the test is unreliable as one colour obscures another. Except in rough, preliminary analyses, the flame test is little used by chemists. There are more precise methods of identifying elements.

Other burners based on the same principle exist. The most important alternatives to the Bunsen burner are:

Teclu burner
The lower part of its tube is conical, with a round screw nut below its base. The gap, set by the distance between the nut and the end of the tube, regulates the influx of the air in a way similar to the open slots of the Bunsen burner. The Teclu burner provides better mixing of air and fuel and can achieve higher flame temperatures than the Bunsen burner.


Teclu Burner

Meker burner
The lower part of its tube has more openings with larger total cross-section, admitting more air and facilitating better mixing of air and gas. The tube is wider and its top is covered with a wire grid. The grid separates the flame into an array of smaller flames with a common external envelope, and also prevents flashback to the bottom of the tube, which is a risk at high air-to-fuel ratios and limits the maximum rate of air intake in a conventional Bunsen burner. Flame temperatures of up to 1100–1200 °C (2000–2200 °F) are achievable if properly used. The flame also burns without noise, unlike the Bunsen or Teclu burners

Meker Burner

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The Northern Lights or Aurora Borealis

The Northern Lights or Aurora Borealis

An aurora is a natural light display in the sky particularly in the high latitude (Arctic and Antarctic) regions, caused by the collision of energetic charged particles with atoms in the high altitude atmosphere (thermosphere). The charged particles originate in the magnetosphere and solar wind and, on Earth, are directed by the Earth's magnetic field into the atmosphere. Most aurorae occur in a band known as the auroral zone, which is typically 3° to 6° in latitudinal extent and at all local times or longitudes. The auroral zone is typically 10° to 20° from the magnetic pole defined by the axis of the Earth's magnetic dipole. During a geomagnetic storm, the auroral zone expands to lower latitudes.

 

In northern latitudes, the effect is known as the aurora borealis (or the northern lights), named after the Roman goddess of dawn, Aurora, and the Greek name for the north wind, Boreas, by Pierre Gassendi in 1621.

Auroras seen near the magnetic pole may be high overhead, but from farther away, they illuminate the northern horizon as a greenish glow or sometimes a faint red, as if the Sun were rising from an unusual direction. Discrete aurorae often display magnetic field lines or curtain-like structures, and can change within seconds or glow unchanging for hours, most often in fluorescent green.

Its southern counterpart, the aurora australis (or the southern lights), has features that are almost identical to the aurora borealis and changes simultaneously with changes in the northern auroral zone. It is visible from high southern latitudes in Antarctica, South America, New Zealand, and Australia.

Aurora timelapse:-

 

What is happening?

The auroras, both surrounding the north magnetic pole (aurora borealis) and south magnetic pole (aurora australis) occur when highly charged electrons from the solar wind interact with elements in the earth's atmosphere. Solar winds stream away from the sun at speeds of about 1 million miles per hour. When they reach the earth, some 40 hours after leaving the sun, they follow the lines of magnetic force generated by the earth's core and flow through the magnetosphere, a teardrop-shaped area of highly charged electrical and magnetic fields.

­As the electrons enter the earth's upper atmosphere, they will encounter atoms of oxygen and nitrogen at altitudes from 20 to 200 miles above the earth's surface. The colour of the aurora depends on which atom is struck, and the altitude of the meeting.

• Green - oxygen, up to 150 miles in altitude
• Red - oxygen, above 150 miles in altitude
• Blue - nitrogen, up to 60 miles in altitude
• Purple/violet - nitrogen, above 60 miles in altitude

All of the magnetic and electrical forces react with one another in constantly shifting combinations. These shifts and flows can be seen as the auroras "dance," moving along with the atmospheric currents that can reach 20,000,000 amperes at 50,000 volts.

Structure of the Magnetosphere

For more information visit:-

http://science.howstuffworks.com/nature/climate-weather/atmospheric/question471.htm

http://en.wikipedia.org/wiki/Aurora_borealis

Using digital SLRs to measure the height of Northern Lights

Scientific research doesn’t often start from outreach projects. Yet, Ryuho Kataoka from the National Institute of Polar Research in Tokyo, Japan, came up with an idea for a new method to measure the height of aurora borealis after working on a 3D movie for a planetarium. Kataoka and collaborators used two digital single-lens reflex (SLR) cameras set 8 km apart to capture 3D images of Northern Lights and determine the altitude where electrons in the atmosphere emit the light that produces aurora. The results are published today in Annales Geophysicae, a journal of the European Geosciences Union (EGU).

“We had initial success when we projected the digital SLR images at a planetarium and showed that the aurora could be seen in 3D. It was very beautiful, and I became confident that it should be possible to calculate the emission altitude using these images,” recalls Kataoka, who also works at the Graduate University for Advanced Studies (Sokendai) in Hayama, Japan. He teamed up with other Japanese researchers and an American scientist to do just that.

The separation distance between the human eyes is what allows us to see in 3D. When we look at an object, the images captured by the left and right eyes are slightly different from each other and when combined they give the brain the perception of depth. But because the distance between our eyes – about 5 cm – is small, this only works for objects that are not very far away.
Since aurora extend between about 90 and 400 km in altitude, a much larger separation distance is needed to see them in 3D. The researchers used two cameras, mimicking the left and right eyes, separated by 8 km across the Chatanika area in Alaska. Their two digital SLRs, equipped with fisheye lenses and GPS units, captured two simultaneous all-sky images that the researchers combined to create a 3D photograph of the aurora and measure the emission altitude.

“Using the parallax of the left-eye and the right-eye images, we can calculate the distance to the aurora using a [triangulation] method that is similar to the way the human brain comprehends the distance to an object,” explains Kataoka. Parallax is the difference in the apparent position of an object when observed at different angles.

Scientists have obtained altitude maps of aurora before. They are useful because they provide information about the energy of the electrons that produce the lights. But this is the first time the emission height of Northern Lights has been measured using images captured with digital SLR cameras. As the authors explain in the new Annales Geophysicae paper, the altitude maps obtained in this way are consistent with previous observations.
The technique is low cost and allows researchers to measure the altitude of small-scale features in the aurora. Further, it opens up the door for citizen scientists to get involved with auroral research.

“Commercially available GPS units for digital SLR cameras have become popular and relatively inexpensive, and it is easy and very useful for photographers to record the accurate time and position in photographic files. I am thinking of developing a website with a submission system to collect many interesting photographs from night-sky photographers over the world via the internet,” says Kataoka.

The researchers believe this may lead to new scientific findings, while working to engage the public in auroral research. After all, it was the beauty of 3D imaging of auroras that inspired Kataoka to develop a new tool for scientific research in the first place.

For more information, the scientific article is available online, free of charge, at http://www.ann-geophys.net/31/1543/2013/angeo-31-1543-2013.html.

Hearing Protection

Exposure to noise at work causing hearing loss is still a significant occupational illness.

Employers have a duty of care to protect their employees while at work and this may mean providing personal protective equipment.  In the case of loud environments this may be ear plugs or ear muffs.

It can be tempting to pick the hearing protection with the highest level of protection (or attenuation), however 'over attenuation' can bring it's own problems.  If the sound level at the ear is reduced too far, the wearer can become isolated, unable to hear people's voices, moving vehicles or warning sounds/alarms.

In a workplace where noise may be an issue the noise level needs to be measured.  This is covered by the Control of Noise at Work Regulations 2005.  Between 80 and 85db(A) hearing protection is not compulsory but is made available to workers for their comfort and protection.  Above this hearing protection is compulsory.  These regulations give a new limit of 87db at the ear (under hearing protective equipment) which must not be exceeded.

Ear plugs can be used against various sound levels which are normally disposable.  Alternatively ear muffs similar to those shown above can be used.

Please check out the link below for more information.
http://www.prlabs.co.uk/news/article.php?Id=209
http://en.wikipedia.org/wiki/Personal_protective_equipment

The Microscope

The optical microscope, often referred to as the "light microscope", is a type of microscope which uses visible light and a system of lenses to magnify images of small samples. Optical microscopes are the oldest design of microscope and were possibly designed in their present compound form in the 17th century. Basic optical microscopes can be very simple, although there are many complex designs which aim to improve resolution and sample contrast. Historically optical microscopes were easy to develop and are popular because they use visible light so that samples may be directly observed by eye.

Binocular Microscope

 

There are two basic configurations of the conventional optical microscope: the simple (single lens) and the compound (many lenses). The vast majority of modern research microscopes are compound microscopes while some cheaper commercial digital microscopes are simple single lens microscopes. A magnifying glass is, in essence, a basic single lens microscope. In general, microscope optics are static; to focus at different focal depths the lens to sample distance is adjusted, and to get a wider or narrower field of view a different magnification objective lens must be used. Most modern research microscopes also have a separate set of optics for illuminating the sample

It is difficult to say who invented the compound microscope. Dutch spectacle-makers Hans Janssen and his son Zacharias Janssen are often said to have invented the first compound microscope in 1590.

Christiaan Huygens, another Dutchman, developed a simple 2-lens ocular system in the late 17th century that was achromatically corrected, and therefore a huge step forward in microscope development. The Huygens ocular is still being produced to this day, but suffers from a small field size, and other minor problems.

In August 1893 August Köhler developed Köhler illumination. This method of sample illumination gives rise to extremely even lighting and overcomes many limitations of older techniques of sample illumination. Before development of Köhler illumination the image of the light source, for example a lightbulb filament, was always visible in the image of the sample.

For more information on microscopes visit:-

http://en.wikipedia.org/wiki/Optical_microscope

Or visit http://www.prlabs.co.uk/news/article.php?Id=207 and read all about our range of Visiscope Microscopes.

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Radium

Radium is a chemical element with symbol Ra and atomic number 88. Radium is an almost pure-white alkaline earth metal, but it readily oxidizes on exposure to air, becoming black in colour. All isotopes of radium are highly radioactive, with the most stable isotope being radium-226, which has a half-life of 1601 years and decays into radon gas. Because of such instability, radium is luminescent, glowing a faint blue

Radium, in the form of radium chloride, was discovered by Marie Curie and Pierre Curie in 1898. They extracted the radium compound from uraninite and published the discovery at the French Academy of Sciences five days later. Radium was isolated in its metallic state by Marie Curie and André-Louis Debierne through the electrolysis of radium chloride in 1910. Since its discovery, it has given names like radium A and radium C2 to several isotopes of other elements that are decay products of radium-226.

Radium is not very interesting to biologists because it is not necessary for life. It is, in fact, quite harmful to life due to its radioactivity and chemical reactivity. However, this did not stop a 30-year radium craze in the United States, where some people and manufacturers claimed radium to be a "wonder drug" and added it to all sorts of items, from toothpastes and suppositories to foods and even to drinking water, claiming it prevented or cured all sorts of ailments, ranging from arthritis and cancer to mental illness.  Yet at the same time that radium's health effects were being touted, it was also being added to pesticides and insecticides.

Radium is luminescent, glowing a lovely pale blue colour. This quality led to it being incorporated into a paint for watch and clock hands and dials in the United States, causing the deaths of many dial painters (all young women) who used their lips to give their paint brushes a fine point. These women, dubbed "Radium Girls", ended up suffering from a number of health problems such as anemia and cancer. Some Radium Girls ingested so much radium that their hair, hands, faces and arms glowed a luminous pale blue in the dark.

Radium covered watch hands under UV light

It wasn't as though there wasn't adequate warning of radium's dangers; its discoverer, Nobel-laureate Marie Curie, noted that a vial containing radium that she carried in her pocket caused an ulcer to appear on her skin. She later died of aplastic anaemia, most likely due to her years of exposure to radiation.

Desiccators

Desiccators are sealable enclosures containing desiccants used for preserving moisture-sensitive items such as cobalt chloride paper for another use. A common use for desiccators is to protect chemicals which are hygroscopic or which react with water from humidity.


Desiccator

The contents of desiccators are exposed to atmospheric moisture whenever the desiccators are opened. It also requires some time to achieve a low humidity. Hence they are not appropriate for storing chemicals which react quickly or violently with atmospheric moisture such as the alkali metals.

The lower compartment of the desiccator contains lumps of freshly calcined quicklime or (not as effective) calcined calcium chloride to absorb water vapours. The substance is put in the upper compartment (on the porcelain plate). The ground-glass rim of the desiccator lid must be thoroughly greased with a thin layer of petroleum jelly melted together with beeswax or paraffin wax.

In order to open the desiccator without damage, remove the lid sideways horizontally not to upwards. Cover the desiccator in the same way.

In laboratory use, the most common desiccators are circular and made of heavy glass. There is usually a removable platform on which the items to be stored are placed. The desiccant, usually an otherwise-inert solid such as silica gel, fills the space under the platform.

A stopcock may be included to permit the desiccator to be evacuated. Such models are usually known as vacuum desiccators. When a vacuum is to be applied, it is a common practice to criss-cross the vacuum desiccator with tape, or to place it behind a screen to minimize damage or injury caused by an implosion. To maintain a good seal, vacuum grease is usually applied to the flanges.
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