How to Make Phosphorus

An explanation of how phosphorus can be made.

Phosphorus was first isolated in 1669 by an alchemist called Hennig Brand. He believed that the yellow colour of urine was due to gold and he had been trying to devise a method of extracting it. After roasting a paste of stale urine, he boiled it dry until an intense white glow emanated from his apparatus. He had just become the first person to isolate a new element since antiquity.

Phosphorus can be used to make bone china, baking powder, food additives, detergents and fertilisers.

Brand had isolated phosphorus because of the ammonium sodium hydrogen phosphate dissolved in urine (55mg of phosphorus can be obtained from each litre of urine processed). The English chemist Robert Boyle managed to improve on Brand’s technique by intensely heating sodium phosphate (from urine) with sand and coke to give sodium silicate, carbon monoxide and phosphorus vapour which was passed through water and sank to the bottom of the container so that the phosphorus did not burn off. The carbon monoxide just bubbled off and the sodium silicate stayed in the crucible, keeping the phosphorus relatively pure.

A more abundant source of phosphorus than urine is bones – about one-eighth the mass of bones is phosphorus – which exists as calcium phosphate. The bones should be degreased first by immersing in a warm solution of one molar caustic soda (sodium hydroxide). I have found that about one-twentieth the mass of the bones is lost after this. The bones are then burnt until they are highly charred and then broken down into a dark powder. Heat over a hot flame, mixed with sand and charcoal. This should take place in a well ventilated place (ideally outside) because the carbon monoxide liberated by this reaction is extremely toxic. Collect the vapour using an inverted funnel above the reaction mixture and pass through water for the phosphorus to condense in. The white phosphorus should be left in sunlight until it turns into red phosphorus, which is much safer to handle.

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One Response to “How to Make Phosphorus”
  1. Eden Says...

    On December 26, 2010 at 9:22 pm

    Amazing! Can phosphor be obtained in similar fashion with other materials, such as coffee grounds (lower yield perhaps)?

    When distilled, would the solid residue be urea?


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