Cobalt Wonders- Invisible Ink, Indrajal Flowers, Magnetic Bombs, Cobalt Therapy (Post No.6218)

Written by London swaminathan

Date: 21 March 2019

GMT Time uploaded in London – 20-32

Post No. 6218

Pictures shown here are taken from various sources including google, Wikipedia, Facebook friends and newspapers. This is a non- commercial blog. ((posted by AND

Cobalt is an essential element for human beings. It is the heart of B12 vitamin. Lack of it will produce fewer red corpuscles and cause anaemia.

People are familiar with cobalt blue colour in glass and ceramic materials. But it is used in other ways as well.
There are very interesting titbits about this element
Cobalt name came from goblin. Sixteenth century Saxony miners tried to extract sliver from cobalt ores thinking that they were silver ores. But they were disappointed to find toxic fumes of arsenic were given off. It was indeed cobalt arsenide. They cursed the ores saying that it had been bewitched by goblins.

Egyptians, Sumerians and ancient Chinese used it.
Cobalt blue is famous because of the glass and ceramic materials with cobalt blue colour.
Cobalt requirement of human body comes from food. Clams, sardines, salmon herring, liver and eggs contain B12.

Magnetic Mines 

Cobalt steel with highly magnetic properties was used by Nazi Germany in the making of magnetic mines. Those mines were triggered by the magnetic field of British ships and were sinking British ships. But Britain put degaussing coils around its ships and then Germany used them to make bombs which damaged British buildings.

Cobalt producing countries— Zaire, Canada , Morocco, Sweden.

Georg Brandt of Stockholm discovered it.
Magnetised cobalt has some advantages over iron magnets. They have magnetism even at higher temperatures.
Stellite made with cobalt, tungsten and other elements is used to make cutting tools.
Mainly used in colouring glass and ceramic materials.
Cobalt 60 is a radioactive isotope. It is used in cobalt therapy and irradiating preserved food.

Chemical properties

Symbol Co
Atomic number 27
Melting point 1495 degree C
Boiling point 2870 C
It is a lustrous silvery blue metal.

Invisible Inks

Cobalt was once used to make invisible ink. When cobalt chloride solution was used to write messages, it would become invisible. When it is heated the message would appear and can be read easily. Spies used it to send secret messages using this property. They would use cobalt chloride for writing secret messages. On top of it they use normal ink to write innocent messages. Only spies would know the secrets.

In the nineteenth century artificial flowers were coated with cobalt chloride. As the weather becomes hotter it would turn from pink to violet and then to blue. Indrajal (magic) was done with colour changes.

source:-Nature’s Building Blocks by John Emsley


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