On this day in history - the first patent for carbon paper was secured

In 1806, Englishman Ralph Wedgwood secured the first patent for carbon paper, which he described as an “apparatus for producing duplicates of writings.” In his process, thin paper was saturated with printer's ink, then dried between sheets of blotting paper.

His idea for the carbon paper was a byproduct of his invention of a machine to help blind people write, and the “black paper” was really just a substitute for ink. In its original form, Wedgwood's “Stylographic Writer” employed a metal stylus instead of a quill for writing, with the carbon paper placed between two sheets of paper in order to transfer a copy onto the bottom sheet.

A sheet of carbon paper, with the coating side down. 

The manufacture of carbon paper was formerly the largest consumer of montan wax. In 1954 the Columbia Ribbon & Carbon Manufacturing Company filed a patent for what became known in the trade as solvent carbon paper: the coating was changed from wax-based to polymer-based.

The manufacturing process changed from a hot-melt method to a solvent-applied coating or set of coatings. It was then possible to use polyester or other plastic film as a substrate, instead of paper, although the name remained carbon paper.

For more information visit:-

http://www.todayinsci.com/10/10_07.htm

https://en.wikipedia.org/wiki/Carbon_paper

https://www.prlabs.co.uk/lab-supplies.php?N=carbon-capsule&Id=44459

What is a Rotary Evaporator?

A rotary evaporator is a device used in laboratories for the efficient and gentle removal of solvents from samples by evaporation. Scientists often talk about a sample being evaporated under reduced pressure - ie in a rotary evaporator.

Rotary evaporators are also used in molecular cooking for the preparation of distillates and extracts.

 

The main components of a rotary evaporator are:

1. A motor unit that rotates the evaporation flask or vial containing the user's sample.
2. A vapour duct that is the axis for sample rotation, and is a vacuum-tight conduit for the vapour being drawn off of the sample.
3. A vacuum system, to substantially reduce the pressure within the evaporator system.
4. A heated fluid bath (generally water) to heat the sample.
5. A condenser with either a coil passing coolant, or a "cold finger" into which coolant mixtures such as dry ice and acetone are placed.
6. A condensate-collecting flask at the bottom of the condenser, to catch the distilling solvent after it re-condenses.
7. A mechanical or motorised mechanism to quickly lift the evaporation flask from the heating bath.

The vacuum system used with rotary evaporators can be as simple as a water aspirator with a trap immersed in a cold bath (for non-toxic solvents), or as complex as a regulated mechanical vacuum pump with refrigerated trap.

Glassware used in the vapour stream and condenser can be simple or complex, depending upon the goals of the evaporation, and any propensities the dissolved compounds might give to the mixture (e.g., to foam or "bump").

Commercial instruments are available that include the basic features, and various traps are manufactured to insert between the evaporation flask and the vapour duct. Modern equipment often adds features such as digital control of vacuum such as the KNF SC950 unit shown below, digital display of temperature and rotational speed, and vapour temperature sensing.

Users of rotary evaporators must take precautions to avoid contact with rotating parts, particularly entanglement of loose clothing, hair, or necklaces. Under these circumstances, the winding action of the rotating parts can draw the users into the apparatus resulting in breakage of glassware, burns, and chemical exposure. Extra caution must also be applied to operations with air reactive materials, especially when under vacuum. A leak can draw air into the apparatus and a violent reaction can occur.  Care must also be taken to avoid implosions resulting from use of glassware that contains flaws, such as star-cracks. Explosions may occur from concentrating unstable impurities during evaporation.

What would it be like... if you could just disappear from the daily lab routine? As easily and quickly as liquid escapes from the rotary evaporator? This is the fantasy in the IKA image video above.

For more information visit:-
http://en.wikipedia.org/wiki/Rotary_evaporator
https://www.prlabs.co.uk/news/article.php?Id=120
http://www.knf.co.uk/products/laboratory-pumps/product/categories/vacuum-pump-systems/
http://www.ika.com/Products-Lab-Eq/Rotary-Evaporators-Rotary-evaporator-distilling-distillation-cph-35/
http://www.heidolph-instruments.com/products/rotary-evaporators/
http://www.stuart-equipment.com/category.asp?dsl=118&mnu=23

All available through P&R Labpak Limited

What is a Soxhlet Extractor?

A Soxhlet extractor is a piece of laboratory apparatus invented in 1879 by Franz von Soxhlet. It was originally designed for the extraction of a lipid from a solid material. However, a Soxhlet extractor is not limited to the extraction of lipids. Typically, a Soxhlet extraction is only required where the desired compound has a limited solubility in a solvent, and the impurity is insoluble in that solvent. If the desired compound has a significant solubility in a solvent then a simple filtration can be used to separate the compound from the insoluble substance.

Normally a solid material containing some of the desired compound is placed inside a thimble made from thick filter paper, which is loaded into the main chamber of the Soxhlet extractor. The Soxhlet extractor is placed onto a flask containing the extraction solvent. The Soxhlet is then equipped with a condenser.

The solvent is heated to reflux. The solvent vapour travels up a distillation arm, and floods into the chamber housing the thimble of solid. The condenser ensures that any solvent vapour cools, and drips back down into the chamber housing the solid material.

The chamber containing the solid material slowly fills with warm solvent. Some of the desired compound will then dissolve in the warm solvent. When the Soxhlet chamber is almost full, the chamber is automatically emptied by a siphon side arm, with the solvent running back down to the distillation flask. The thimble ensures that the rapid motion of the solvent does not transport any solid material to the still pot. This cycle may be allowed to repeat many times, over hours or days.

During each cycle, a portion of the non-volatile compound dissolves in the solvent. After many cycles the desired compound is concentrated in the distillation flask. The advantage of this system is that instead of many portions of warm solvent being passed through the sample, just one batch of solvent is recycled.

After extraction the solvent is removed, typically by means of a rotary evaporator, yielding the extracted compound. The non-soluble portion of the extracted solid remains in the thimble, and is usually discarded.

For more information:-
http://en.wikipedia.org/wiki/Soxhlet_extractor
http://www.scilabware.com/Extraction-&-Fractionation/Soxhlet--Extraction/Soxhlet-complete-assemblies/p-51-52-208/
(Scilabware, Pyrex, Quickfit glassware available from P&R Labpak)