Hennig Brand

File:Henning brand.jpg

The Alchemist in Search of the Philosophers Stone (1771) by Joseph Wright depicting Henning Brand discovering phosphorus (the glow shown is exaggerated)

Henning Brand (c.1630 – c.1710) was an unsuccessful merchant and amateur alchemist in Hamburg, Germany, who was the first person to discover the pure element phosphorus .

The circumstances of Brand's birth are unknown. Some said his origins were humble and that he had been an apprentice glass-maker as a young man. But in one letter his second wife Margaretha said he was of high social standing. In any case he held a post as a junior army officer during the Thirty Years' War and his first wife's dowry was substantial, allowing him to pursue alchemy on leaving the army.

Alchemy

Brand was, like alchemists of the time, searching for the "philosopher's stone", a substance which would turn base metals (like lead) into gold. By the time his first wife died he had exhausted her money on that fruitless search. He then married his second wife Margaretha who was a wealthy widow and her money let him continue the search.

Like many before him, he was interested in urine and tried combining it with various other materials, in hundreds of combinations. He had seen for instance a recipe in a book 400 Auserlensene Chemische Process by F. T. Kessler of Strasbourg for using alum, saltpetre (potassium nitrate) and concentrated urine to turn base metals into silver (a recipe which of course didn't work).

Around 1669 he heated residues from boiled-down urine on his furnace until the retort was red hot, where all of a sudden glowing fumes filled it and liquid dripped out, bursting into flames. He could catch the liquid in a jar and cover it, where it solidified and continued to give off a pale-green glow. What he collected was phosphorus, which he named from the Greek for "light-bearing" or "light-bearer."

Phosphorus must have been awe-inspiring to an alchemist. A product of man, and seeming to glow with a life force that didn't diminish over time (and didn't need re-exposure to light like previously discovered Bologna stone). Brand kept his discovery secret, again as alchemists of the time did, and worked with the phosphorus trying to use it to produce gold (unsuccessfully of course).

He no doubt refined his production method over time, the version published later by Leibniz was

• Boil urine to reduce it to a thick syrup.
• Heat until a red oil distills up from it, and draw that off.
• Allow the remainder to cool, where it consists of a black spongy upper part and a salty lower part.
• Discard the salt, mix the red oil back into the black material.
• Heat that mixture strongly for 16 hours.
• First white fumes come off, then an oil, then phosphorus.
• The phosphorus may be passed into cold water to solidify.

The chemical reaction Brand stumbled on was as follows. Urine contains phosphates PO₄^3-, as sodium phosphate (ie. with Na⁺), and various carbon-based organics. Under strong heat the oxygens from the phosphate react with carbon to produce carbon monoxide CO, leaving elemental phosphorus P, which comes off as a gas. Phosphorus condenses to a liquid below about 280°C and then solidifies (to the white phosphorus allotrope) below about 44°C (depending on purity). This same essential reaction is still used today (but with mined phosphate ores, coke for carbon, and electric furnaces).

The phosphorus Brand's process yielded was far less than it could have been. The salt part he discarded contained most of the phosphate. He used about 5,500 litres of urine to produce just 120 grams of phosphorus. If he'd ground up the entire residue he could have got 10 times or 100 times more (1 litre of adult human urine contains about 1.4g phosphorus).

Publicity

By 1675, having been unsuccessful at producing gold, Brand spoke of his phosphorus to friends and soon it was the talk of Hamburg. He enjoyed the fame it brought him, and being a rather pompous man insisted on being called "Herr Doktor".

Alchemist and academic Johann Kunckel had been interested in luminescence for some time and when he heard about Brand's discovery he came from Wittenberg to see it for himself. He wrote of it to fellow alchemist Daniel Kraft in Dresden too. Kunckel wanted to buy phosphorus from Brand, but he would not sell, suspecting Kunckel really wanted the secret of making it.

Kraft came to Hamburg without telling Kunckel, and behind Kunckel's back Brand agreed to sell Kraft all the phosphorus he had and all he could make, and as part of the deal not talk of phosphorus to anyone. Later replying to a letter from Kunckel, Brand revealed this obligation, and Kunckel realized he had been tricked. Kunckel took to mocking Brand and disputing his right to the title Herr Doktor. In time Kunckel succeeding in making phosphorus for himself (though of a lesser quality it seems).

Kraft made money demonstrating phosphorus to various crown heads of state across Europe. One of those was Duke Johann Frederick of Saxony, and attending that demonstration was Gottfried Leibniz, remembered now for calculus but who was interested in all the sciences of his day. In 1677 on a visit to Hamburg, Leibniz by chance learned Brand also had phosphorus, and went to see him. Brand was yet again short of money, so happily owned to being the discover of phosphorus, not Kraft, and even offered the method, for a fee.

Leibniz returned to Hanover where the Duke accepted his recommendation to employ Brand and to offer 6 months salary in advance if he revealed the secret. Brand tried to get a better salary and he negotiated again with Kraft, and with the Duke of Mecklenburg-Güstrow, but in the end accepted Leibniz's offer.

So Brand travelled to Hanover in 1678, setup his equipment and made phosphorus, with all the properties Leibniz had seen Kraft demonstrate. But before long Brand returned to Hamburg, promising to make more phosphorus there, which he didn't. Leibniz wrote asking why and in December Brand replied that he and his children had been ill and unable to work, and he asked for more money.

With an increased salary Brand returned to Hanover in 1679 and again made phosphorus. Leibniz published an account of its manufacture, though omitting Brand's name. That omission was not it seems to try to claim the invention for himself, since when asked he would freely say Brand had shown him.

Some time also in 1679 Ambrose Godfrey, assistant to Robert Boyle, came from London to see Brand, to ask the secret of making phosphorus, since their attempts were unsuccessful. Brand revealed to him that high heat was needed. Godfrey later became one of the most successful early phosphorus manufacturers.

Later life

Little is known about Brand's later life. Leibniz's papers show he was still alive in 1692 and even by 1710 Leibniz had not heard of his death.

The omission of Brand's name from early accounts of phosphorus meant that its discovery was often misattributed to Kunckel, or Kraft, or Leibniz. In fact, Brand's part might have remained unknown altogether if letters from his wife Margaretha were not discovered among Leibniz's papers.

References

• John Emsley, The Shocking History of Phosphorus, 2000, ISBN 0-330-39005-8

Further reading

• Today in science
• Elements - Phosphorus