Chapter 20. Leblanc (Soda)


A Most Easie Way of Acquiring Spirit of Salt Together With the Salt Mirabile.

R. of common salt two parts, dissolve it in a sufficient quantity of common water; pour A upon the solution; put the mixture into a glass Body, or a glass Retort well coated, or else into an earthen Body or Retort. If a Body, set on an Head, and begin to destil with Fire of sand, encreasing your Fire gradually; with the first heat comes off the unsavory Phlegm, which gather apart; when the Liquor comes forth sowrish, change your Receiver and receive the sowre spirit: Continue the operation till no more spirits will arise, then let out the Fire, and permit the Vessel to stand in sand till all is cooled, when cold, take it out, and if it be unbroke, fill it again with the aforesaid matter, and proceed as we taught: The Phlegm is not to be cast away, but must be kept, that in it may be dissolved Salt (because it is better than common water) for another destillation. Thus from every pound of salt you will have lb. 1 of the best and most pure spirit. Dissolve the salt remaining in the Body or Retort (if neither be broke) in Water, filter and evaporate the Water, let it crystallize, the Crystals will be white, endowed with wonderful Virtues, to be declared here following.

 — Rudolf Glauber, Miraculum Mundi, ca. 1658 AD [1]


When I was born in 1742 the king was on his throne, God was in his heaven, and all was right with the world. It would not last. I was orphaned at the age of nine and apprenticed to an apothecary, where I learned my chemistry from sacred texts such as the one quoted above. I studied surgery at college, graduating as Nicolas Leblanc, MD. In 1780 I became physician to the Duke of Orleans and with his patronage devoted myself to the winning of a prize of 2,400 livres offered by the Académie des Sciences for "anyone who should find the most simple and economical method to decompose in bulk salts from the sea, extract the alkali which forms their base in its pure state, free from any acid or neutral combination, in such a manner that the value of this mineral alkali shall not exceed the price of the product extracted from the best foreign sodas."[2] You are probably wondering why the Académie would offer such a prize. I will tell you.

See, the glass business had been using potash or soda ash as a flux ever since about the twenty-fifth century BC (Chapter 13); the paper business needed alkali ever since the first century AD (Chapter 14); and the soap business had filled out by the eighteenth century, which increased the demand for alkalis even more (Chapter 19). And ever since God was a child, folks had been making potash and soda ash by leaching ashes (Chapter 8), lime by burning limestone (Chapter 10), and caustic soda by reacting soda ash and lime (Chapter 15). So alkali was a pretty good business by the eighteenth century, what with increasing demand from lots of different businesses and all.

Any country that had a glass, paper, or soap industry needed soda and to get it they tried burning all kinds of stuff to get ash. The saltwort plant, which grew mostly in Spain and the Canary Islands, was about the best thing to burn, on account of its ash, called barilla, contained about 20% soda. If you didn't want to have to kiss up to Spain, you could burn seaweed, which they did in Ireland and Scotland, but its ash, called kelp, contained only about a third as much soda as barilla did. No matter what you burned, you had to burn lots of it to get a little ash, and not all of that ash was soda. As the eighteenth century wore on, the supply of ash couldn't keep up with the demand for soda and the price doubled from 1750 to 1790. Now the French Academy of Sciences was worried about the dependence of domestic glass and soap on imported soda, so they offered a prize to promote the foundation of a domestic soda industry which would liberate France from Spanish barilla and Scottish kelp.

Pardon me; this was my story.


Earlier, in 1736 the French agriculturalist Henri Louis Duhamel du Monceau had revealed that soda and sea salt were salts of the same base, now known as sodium hydroxide. This being so, he proclaimed that it was possible, in principle, to make soda (sodium carbonate) from sea salt (sodium chloride). This information came down to me—

Like a spider.

More like a revelation, really, and I began to look for an intermediate between salt and soda. Glauber's salt (sodium sulfate) was well known among doctors (Chapter 18) and was easily produced from sea salt and sulfuric acid. If it were possible to convert Glauber's salt to soda, it would prove even more mirabile than had previously been imagined. Several people had taken this approach to the problem and after a thorough review of the successes and failures of my contemporaries—

For inspiration.

—I devised a process for this conversion involving the calcination of limestone, coal, and Glauber's salt in a furnace to produce "black ash," from which soda could be extracted by recrystallization. The Académie had increased the prize to 12,000 livres in 1789 and two years later I was granted a patent from the king. I set up a factory at Saint-Denis with the financial backing of the Duke; at its peak the factory was producing 320 tons of soda per year. Unfortunately, the 1790's were not the best of times for the French nobility, as the Comité du Salu Public provided a brisk trade for the guillotine business. The Duke lost his head in 1793, the plant was confiscated, and the Académie des Sciences abolished.

Now, all I wanted to do was to found a domestic soda industry for the benefit of French glass, paper, and soap makers, collect my prize, and settle down to a life of quiet contemplation. But in the space of a few years the king was de-throned, God seemed to have taken a holiday, and all was not particularly right with my world. Seeing the writing on the wall, I surrendered my patent to the Comité and the details of my process were published in 1797 in the Annales de Chimie. In 1802 Napoleon finally came to the realization that cheap domestic soda would be good for France and returned the now-derelict factory to me, but balked at the suggestion that he make good on the Académie's promised prize. I tried to make a go of it, I really did. But by the time I was allowed to resume my vocation, the secrets of my process had wandered far and wide.

Like spiders.

Like prodigal spiders, perhaps. Facing stiff competition from ungrateful imitators with more capital, my business failed. I must confess that I sank into depression and in a fit of melancholy shot myself in 1806.

By 1810, French soda plants were making 15,000 tons of soda per year. Meanwhile, back in England there was a stiff salt tax which discouraged the black ash process from hopping the Channel, but the salt tax was repealed in 1823.

May I continue?

I thought you were supposed to be dead. So, with the salt tax gone and with inspiration from Leblanc, James Muspratt opened a black ash soda works at Liverpool, near the Cheshire salt fields. Pretty soon everybody and his dog had a soda plant. By 1852, the French soda production of 45,000 tons would be topped by the English production of 140,000 tons per year.

Largely subsuming the chamber acid industry, Leblanc soda would become the foundation of a diversified chemical industry with products that included sulfuric and hydrochloric acids, soda, lime, salt cake (Glauber's salt), and caustic soda. Growing from scattered factories to immense complexes, soda manufacturers would, by the end of the nineteenth century, introduce such modern innovations as toxic waste dumps, water pollution, and acid rain. This pollution would create a climate of government regulation which would force manufacturers to find markets for former waste products. Eventually these new chemicals would become even more profitable than the original ones, leading to another round of industrial growth and rendering the word chemical synonymous with the word poison in the popular culture. But I am getting ahead of myself.



Reference [18], pp. 31-32.


Reference [52].