On this day in history

On July 29th in 1927, the first iron lung (electric respirator) was installed at Bellevue hospital in New York for the post war polio epidemic. The first iron lung was developed at Harvard University by Phillip Drinker and Louis Agassiz Shaw built with two vacuum cleaners. The iron lung is a negative pressure machine which surrounds the patient’s body except for the head, and alternates a negative atmospheric pressure with the ambient one, resulting in rhythmic expansion of the chest cage (and thus inhalation) in response to the negative extra thoracic pressure. During periods of ambient extrathoracic pressure, the lungs deflate. This type of machine is rarely used today.

The first patients of the iron lung were polio sufferers with chest paralysis.

Historically, in 1670, John Mayow demonstrated that air is drawn into the lungs by enlarging the thoracic cavity. He built a model using bellows inside which was inserted a bladder. Expanding the bellows caused air to fill the bladder and compressing the bellows expelled air from the bladder. This was the principle of artificial respiration called “external negative pressure ventilation” or ENPV that would lead to the invention of the iron lung and other respirators.

For more information visit https://en.wikipedia.org/wiki/Iron_lung

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Ultrasonic Baths

An ultrasonic cleaner is a cleaning device that uses ultrasound (usually from 20–400 kHz) and an appropriate cleaning solvent (sometimes ordinary tap water) to clean delicate items. The ultrasound can be used with just water, but use of a solvent appropriate for the item to be cleaned and the soiling enhances the effect. Cleaning normally lasts between three and six minutes, but can also exceed 20 minutes, depending on the object to be cleaned.

Ultrasonic cleaning penetrates even microscopic openings to provide complete cleaning of the objects treated. This makes it one of the most effective, economical and powerful cleaning methods available. It has applications in laboratories, dental and medical technology, microelectronics, precision engineering, cosmetics, optics and the automotive industry. Ultrasonic cleaners are used to clean many different types of objects, including jewellery, lenses and other optical parts, watches, dental and surgical instruments, tools, coins, fountain pens, golf clubs, window blinds, firearms, musical instruments, industrial parts and electronic equipment. They are used in many jewellery workshops, watchmakers’ establishments, and electronic repair workshops

Modern baths tend to have a heavy duty ultrasonic generator which ensures that the ultrasonic output remains constant, regardless of the bath temperature, fill level and cleaning material. This feature guarantees consistent and reproducible cleaning results. ‘Frequency sweeping’, a frequency modulation of the ultrasonic output generated, prevents ‘standing waves’ from being generated and ensures extremely homogeneous energy distribution in the cleaning bath.
Ultrasonic bath
Ultrasonic cleaning uses Cavitation bubbles induced by high frequency pressure (sound) waves to agitate a liquid. The agitation produces high forces on contaminants adhering to substrates like metals, plastics, glass, rubber, and ceramics. This action also penetrates blind holes, cracks, and recesses. The intention is to thoroughly remove all traces of contamination tightly adhering or embedded onto solid surfaces. Water or other solvents can be used, depending on the type of contamination and the workpiece.
There are various ways to test the level of ultrasonic activity within an ultrasonic bath..

There are a number of recommended tests for establishing levels of ultrasonic activity in the bath.

The foil test involves suspending a strip of foil into various locations around the tank. The foil should not touch the base of the tank and should be held in position for around 1 minute. It should then be removed and there should be an even distribution of perforations and small holes on the surface of the foil.

Another test requires the use of Brownes soil test strips. These are plastic strips which have been contaminated to simulate the contamination which might affect surgical instruments. After running an ultrasonic cycle the strips should be taken from the bath and all contamination should have been removed.

An ultrasonic energy meter can also be used to test the level of ultrasonic activity within the tank.

For help and advice on Ultrasonic baths get in touch.
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Why is milk white?

Milk is mostly made up of water, with smaller amounts of fat, protein, minerals, and other compounds. Fats and water don’t usually mix, but in milk the fat and water form an emulsion. It is also a suspension of a multitude of different proteins in water.

In milk, proteins cluster together to form structures called micelles. These clusters grow from small clusters of calcium phosphate, which help hold them togetherThere are a number of different models of these micelles, with the exact structure still being subject to scrutiny.
 
It’s the protein micelles which give milk its white appearance. The micelles are on average about 150 nanometres in diameter, and this very small size means they are able to scatter light that hits them. The overall effect of this scattering by the huge number of micelles in milk is that it looks white.
 
For a fuller explanation and for more information please visit:-
http://www.compoundchem.com/2018/06/02/milk/
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Care and Storage of pH Electrodes

The life of a pH electrode is not infinite. A number of factors affect the life span of a pH electrode. The higher the temperature that the electrode is used at, the more extreme the pH, how often the bulb dries out and needs to be rehydrated, how roughly it is used; all these factors and more shorten the life span of an electrode. An electrode that is well maintained and cared for can last up to 2 years, one that is not well maintained will not last as long, and one that is well maintained will not last significantly longer.

Storage of the pH electrode when not in use.

The pH electrode bulb needs to be moist at all times. When you are done with the electrode pour electrode storage solution into the cap that came with the electrode and put the cap over the bulb of the electrode. Keep the cap on until next use. If the electrode is being stored for a long time you may want to check the cap to be sure the storage solution is still in the cap and keeping the bulb moist. DO NOT STORE THE pH ELECTRODE IN DISTILLED WATER. Storing the pH electrode in distilled water will shorten the life of your pH electrode.

 

If you do not have electrode storage solution use pH 4 buffer solution. If you have neither electrode storage solution or pH 4 buffer solution you can use pH 7 buffer solution for a short time.

 

Rinsing the pH electrode between measurements.

You should rinse your pH electrode between measurements. This can be done with distilled water or rinsing with a sample of the next solution to be measured. Using both distilled water and then a sample of the next solution is also a good way to rinse the pH electrode between measurements.

 

pH electrode fill hole

Some pH electrodes have a fill hole for refreshing the electrolyte in the pH electrode; other pH electrodes do not have a fill hole. If your pH electrode has a fill hole the fill hole cap should be removed during calibration and use. This allows for the correct amount of reference electrolyte to flow into the sample. Replace the fill hole cap when done with the electrode at the end of the day

If bulb dries out, soak electrode bulb in pH 7

pH electrode bulbs should be keep moist at all times. When not in use the pH electrode bulb should be keep moist by pouring electrode storage solution in the cap provided. If the pH electrode bulb does dry out, soak it in pH 7 buffer for a couple of hours before calibrating or taking measurements.

 

Do not wipe the pH electrode with a cloth or any other type of material.

When you are done with the pH meter rinse off the electrode with distilled water, put storage solution in the cap, and put the cap on the end of the pH electrode as described above. If the electrode is wet do not dry it off, let the distilled water evaporate by itself.

 

Cleaning the pH electrode

The pH electrode needs to be cleaned in order to prevent build up of material on the surface of the glass bulb. How often it needs to be cleaned depends upon frequency of use and the material being tested. An electrode used on dark coloured and viscous material usually needs to be cleaned more often than an electrode used on clear thin material.  Material building up on the glass bulb of the electrode will cause the calibration of the electrode to be inaccurate and any subsequent reading to be inaccurate. Follow the instructions supplied with the electrode cleaning solution when cleaning the electrode bulb.

 

Total Lab Supplies offer a wide range of electrodes, storage solutions, buffers and other associated accessories from all major manufacturers including Hanna Instruments, Mettler Toledo, Sentek, Jenway, Schott, WTW etc…

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On this day

In 1980, following a weeklong series of earthquakes and smaller explosions of ash and smoke, the long-dormant Mount St. Helens volcano erupted in Washington state, U.S., hurling ash 15,000 feet into the air and setting off mudslides and avalanches.

Mount St Helens

18/05/1980

An earthquake at 8:32:17 a.m. on Sunday, May 18, 1980, caused the entire weakened north face to slide away, creating the largest landslide ever recorded. This allowed the partly molten, high-pressure gas- and steam-rich rock in the volcano to suddenly explode northwards toward Spirit Lake in a hot mix of lava and pulverized older rock.

Approximately 57 people were killed directly.  Hundreds of square miles were reduced to wasteland, causing over a billion U.S. dollars in damage, thousands of animals were killed, and Mount St. Helens was left with a crater on its north side.

Spirit Lake

Lakes nearest to Mount St. Helens have been partly covered with felled trees for more than thirty years. This photograph was taken in 2012.

For more information visit:-

https://en.wikipedia.org/wiki/1980_eruption_of_Mount_St._Helens

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Today in Science

On this day in history, in 1947, the B.F. Goodrich Company of Akron, Ohio, announced the development of a tubeless tyre.
A technological innovation that would make cars safer and more efficient.
After more than three years of engineering, Goodrich’s tubeless tyre effectively eliminated the inner tube, trapping the pressurised air within the tire walls themselves. By reinforcing those walls, the company claimed, they were able to combine the puncture-sealing features of inner tubes with an improved ease of riding, high resistance to bruising and superior retention of air pressure.  Testing proved successful, and in 1952, Goodrich won patents for the tyre’s various features.  By 1955 tubeless tires became standard equipment on new cars.
Tyres have moved on since with run flat tyres but the basic design has remained the same.
Total Lab Supplies can’t offer tyres but we can offer other safety items.  If you have any requirements get in touch – we can supply safety storage cabinets, spill kits, safety spectacles, signs, labels, gloves and hazardous waste disposal and more
For more information visit:-
https://en.wikipedia.org/wiki/Tubeless_tire
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Separated thermometer columns

Methods For Reuniting Separated Columns In Thermometers

The largest single cause for the failure of precision thermometers in the lab is the separation of mercury columns. This can occur in transit or in the lab. The life of the thermometer can be greatly extended if the following procedures are employed. Other methods may damage the thermometer.

Cooling Method

With the thermometer in an upright position, gradually immerse only the bulb in a solution of solid CO2 (Dry Ice) and alcohol so that the mercury column retreats slowly into the bulb. Do not cool the stem or mercury column. Keep the bulb in the solution until the main column and the separated portion retreat into the bulb. Remove and swing thermometer in a short arc, forcing all the mercury into the bulb.

Most mercury thermometers can be reunited using this method regardless of range (with the exception of deep immersion thermometers) provided only the bulb is immersed in the CO2 and alcohol solution.

Caution: Do not touch the bulb until it has warmed sufficiently for the mercury to emerge from the bulb into the capillary. Never subject the stem or mercury column to the CO2 solution as it will freeze the mercury column in the capillary and may cause the bulb to fracture.

Heating Method

This method applies to thermometers with a maximum range of 260°C (500°F) equipped with expansion chambers sufficiently large to accommodate the separations plus a portion of the main column. Immerse as much of the bulb and stem as possible in a large beaker containing a liquid whose flash point is well above the highest indication of the thermometer being reunited. Heat the beaker, stirring the liquid with the thermometer, until the separation and a portion of the main column enter the chamber. Tap the thermometer in the palm of gloved hand reuniting the column. Allow to cool slowly.

Caution:

  1. Never use an open flame on the bulb.
  1. Never fill the expansion chamber more than two-thirds full.
  1. Make certain the flash point of the liquid is well above the highest temperature indicated on the thermometer.
  1. Thermometers whose ranges exceed 260°C (500°F) cannot be reunited using heat without damaging the instrument.

Reuniting Organic-Filled Columns

Separated columns in organic-filled (spirit) thermometers require a somewhat different technique in order to be reunited. The simplest and safest method is to force the liquid down the capillary by using a centrifuge, if one is available, with a cup deep enough to ensure that the centrifugal force is below the liquid column. Carefully insert the thermometer, bulb down, in the centrifuge. Have some cotton wadding at the bottom of the cup to prevent any damage to the bulb. Turn on the centrifuge and in just a few seconds all the liquid will be forced past the separation. If the cup is not deep enough and all the centrifugal force is not below the column, the column will split, forcing part of the liquid down. The remainder will be forced up, filling the expansion chamber.

If a centrifuge is not available, the column can be reunited by getting the liquid to run down. This can be accomplished by holding the thermometer in an upright position and gingerly tapping the stem above the separation against the palm of your hand. As you gently tap the thermometer, observe the liquid above the separation until it breaks away from the wall of the capillary and runs down to join the main column.

Remember, mercury in glass thermometers are no longer available.  Contact us for equivalent thermometers which can be supplied as they are or with UKAS calibrations.

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The chemistry behind why you shouldn’t eat laundry pods

Laundry pods have featured in the news this week after cases of people eating them in what’s being referred to as the ‘Tide Pod Challenge’. In case you didn’t already realise that this is a pretty terrible idea, this graphic looks at the chemical reasons why you really don’t want them anywhere near your mouth

The Chemistry of Laundry pods



Eating laundry pods is particularly risky since the detergents are at a higher concentration than in liquid detergents. They are highly alkaline; just as highly acidic substances can cause burns, so too can very alkaline ones. If you eat a laundry pod, you run the risk of burns to your throat and stomach from the high concentration detergent they contain. As they pop in your mouth, they can also be accidentally inhaled – definitely not good for your airway and lungs either.

In addition, eating them can also cause breathing problems. Why exactly this is is currently unclear. It seems that in some laundry pod formulations, a sedative effect is seen when they are ingested. This can lead to drowsiness and breathing difficulties. It’s been speculated that a solvent used in the pods, propylene glycol, might contribute. Alternatively, it might be an unknown effect of certain ethoxylated alcohols.


Laundry pods like this also contain a bitter substance to deter children from putting them in their mouths.  For more information visit the full article at the excellent Compound Interest


http://ift.tt/2GiQClE


For all your chemical needs contact us on 01744 455000


TOTAL LAB SUPPLIES

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Happy New Year!

When is it too late to say Happy New Year?  When you first meet someone after the holiday break?  After the first week?  Second week?


Anyway, Total Lab Supplies wishes you a Happy New Year and all the best for 2018.


If you require a catalogue then please contact us on 01744 455000 or e-mail sales@totallabsupplies.co.uk


We can supply a wide range of branded chemicals from Fisher, Acros, Alfa, Honeywell, Fluka and more.  From solvents and acids to more specialist chemicals.  All at competitive prices.  Buying these chemicals you can be assured of quality products.


Please don’t hesitate to get in touch with us and we’ll help you find what you’re looking for.

 

 

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On this day in science history: the first U.S. patent for a liquid soap was issued

In 1865, the first U.S. patent for a liquid soap was issued to William Sheppard of New York City (No. 49,561). The patent described his “discovery that by the addition of comparatively small quantities of common soap to a large quantity of spirits of ammonia or hartshorn is thickened to the consistency of molasses, and a liquid soap is obtained of superior detergent qualities.” The proportions given were to dissolve one pound of common soap in water or steam, and then add 100-lbs of ammonia such that the liquid thickens to the consistency of molasses. The product was expected to be useful for both domestic and manufacturing purposes. (Hartshorn is an ancient name for an aqueous solution of ammonia).
 
Decorative soaps, by Phanton at English Wikipedia (Transferred from en.wikipedia to Commons.) [Public domain], via Wikimedia Commons
So, how does soap clean?
 
Action of soap
 
When used for cleaning, soap allows insoluble particles to become soluble in water, so they can then be rinsed away. For example: oil/fat is insoluble in water, but when a couple of drops of dish soap are added to the mixture, the oil/fat dissolves in the water. The insoluble oil/fat molecules become associated inside micelles, tiny spheres formed from soap molecules with polar hydrophilic (water-attracting) groups on the outside and encasing a lipophilic (fat-attracting) pocket, which shields the oil/fat molecules from the water making it soluble. Anything that is soluble will be washed away with the water.
 
Effect of the alkali
 
The type of alkali metal used determines the kind of soap product. Sodium soaps, prepared from sodium hydroxide, are firm, whereas potassium soaps, derived from potassium hydroxide, are softer or often liquid. Historically, potassium hydroxide was extracted from the ashes of bracken or other plants. Lithium soaps also tend to be hard—these are used exclusively in greases.
 
Effects of fats
 
Soaps are derivatives of fatty acids. Traditionally they have been made from triglycerides (oils and fats). Triglyceride is the chemical name for the triesters of fatty acids and glycerin. Tallow, i.e., rendered beef fat, is the most available triglyceride from animals. Its saponified product is called sodium tallowate. Typical vegetable oils used in soap making are palm oil, coconut oil, olive oil, and laurel oil. Each species offers quite different fatty acid content and hence, results in soaps of distinct feel. The seed oils give softer but milder soaps. Soap made from pure olive oil is sometimes called Castile soap or Marseille soap, and is reputed for being extra mild. The term “Castile” is also sometimes applied to soaps from a mixture of oils, but a high percentage of
olive oil.
 
For more information visit:-
 

 

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