The Great Scientists Of The Seventeen Hundreds

I've always wanted to stroll down Nightingale Lane in London, the trouble is that I want to do it by time travel back to over two hundred years ago. Since time travel appears to not going to happen in my life-time, I guess I'll settle for telling you why this particular place and time has a fascination for me.

For me, it's all about wanting to meet first hand a tall, thin man in old-fashioned clothes which varied hardly at all in fashion or material from year to year.

Of all of the strollers, he was probably the least interesting in appearance. He never looked at passers-by, and he seemed greatly confused and ill at ease when obliged to speak to anyone.

Few today would know that this slightly shabby individual was nephew of the Duke of Devonshire and grandson of the Duke of Kent, and that there was more than a million pounds deposited to his credit in the Bank of England.

Other strollers on that lane would be even more surprised to learn that this timid man was one of the most famous chemists in Europe, Henry Cavendish. He was the man who discovered that water is a compound of two gases. For two thousand years before him, it had been thought to be an element.

Henry Cavendish (1731-1810) was born in Nice, France, of English parents. Nearly all his life was spent in London, where he had two houses. He lived in one and kept his library in the other.

Once a week, he dined with certain members of the Royal Society (a scientific association), but he avoided all other company, especially that of his own family -- and all women. Even the women servants in his house were ordered to keep out of his sight. (This avoidance is one of the many reasons I would have liked to have time traveled to see for myself).

When Cavendish was only twenty-four, Joseph Black of Scotland had discovered that bubbles of carbon dioxide (which he called fixed air) were given off when acids were poured on chalk.

Cavendish tried pouring different acids on metals. He found that when he poured sulphuric acid on zinc, or hydrochloric acid on tin -- a gas bubbled up which turned a pale blue flame.

He called it inflammable air, but we now know this to be the lightest of all substances, hydrogen.

Later, he discovered the composition of nitric acid. He made a number of important discoveries in electricity, but he cared so little for public notice that he did not publish the notes of his work. In fact they were not published until sixty-nine years later, after his death. By that time, other scientists had independently made the same discoveries.

Cavendish's last great work was a series of experiments to find the specific gravity of the earth.

Joseph Black was another interesting scientist. He discovered carbon dioxide. Black was a chemist who taught at the University of Glasgow, and later in Edinburgh.

Though at first he had been a believer in the phlogiston theory, he came to see that there is no such thing as negative weight. Phlogiston was a "substance with minus weight, believed in by serious scholars for many years).

Black was the first to point out the difference between heat and temperature. He had the honor of belonging to the French Academy of Sciences as a foreign member.

In 1774, two years before the American Declaration of Independence, an English Presbyterian preacher made a revolutionary discovery in chemistry.

He heated red oxide of mercury with a burning glass and found that a very remarkable gas was given off.

One August day, he focused sunlight on the red powder. Presently he saw bubbles rise through the water trough, bubbles of a transparent, colorless, odorless something which looked exactly like ordinary air.

However, when he tested this gas, he found that candles would remain lighted in it with a remarkably vigorous flame. Mice lived more than twice as long as in a similar amount of ordinary air, and a red-hot iron wire blazed furiously.

The substance, of course, was oxygen, but the discoverer, Joseph Priestley called it "dephlogisticated air" meaning air with phlogiston taken out.

Born in a tiny village in Yorkshire, Priestley received a rather good education in languages. He spoke French, German, Italian, Arabic, Chaldee, and Syriac). However, he received no formal instruction in science.

In his early years his salary as pastor of a small chapel was so small that he had to teach school and also give private lessons in order to support his family.

Priestley's most important work in science was done when he was minister of the Mill Hill Chapel at Leeds, in northern England. There is was also librarian for Lord Shelburne, a liberal scholar and statesman.

Although Priestley was unpopular on account of his views in both religion and poltics (he was an ardent supporter of both the American and the French revolutions), he made friends with some of the greatest thinkers of the time.

With James Watt (famous for his work on the steam engine) and Erasmus Darwin (grandfather of Charles Darwin) he founded a scientific club called the Lunar Society, because it met at the full moon so that the members could walk home in the moonlight. Some people of it's day called it the Lunatic Society.

On July 14, 1791, friends of Priestley's arranged a dinner to celebrate the fall of the Bastille in Paris. Hearing of this, an infuriated mob burned Priestley's chapel, tore down his house and destroyed his property and many of his valuable papers.

Remember, at the time, there were not many in England who had any sympathy for the French revolutionists. Three years later, Priestley emigrated to America where he was met at the pier by Governor George Clinton of New York. He became the friend of Thomas Jefferson and George Washington.

Among other discoveries made by Priestley were the deadly poison, carbon monoxide, also ammonia, nitrous oxide (laughing gas), nitric oxide, and sulphurous acid.

He was the first person to prepare and drink soda water and he discovered the fact that plants in sunlight take in carbon dioxide and give off oxygen.

Strangely enough, Priestley never realized just how important the discovery of oxygen was, and he fought for the phlogiston theory to the very last breath of his life.

While the discovery of oxygen is largely considered Priestley's, it was actually a poor Swedish druggist, William Scheele, that had prepared oxygen at least two years before Priestly did.

However, Scheele did not publish his results until 1777 so that the scientific world learned of the new "fire-air" from Priestley.

Scheele was apprenticed to an apothecary when he was fifteen and spent most of his life in poverty as a druggist's clerk and later as the proprietor of a small town pharmacy.

In spite of the hard work necessary to make a living, he found time for an enormous number of experiments.

Scheele discovered the yell-green gas, chlorine. He also discovered uric acid and proved that what we now call lactic acid, is what causes milk to sour.

Antoine Laurent Lavoisier (1743-1794) has been called the father of modern chemistry.

Lavoisier enjoyed as a youth all the advantages denied to Priestley and Scheele. His wealthy father sent him to the College Mazarin in his birthplace, Paris, where he studied mathematics, astronomy, chemistry, and botany under some of the leading scientists of the day.

No one ever worked harder than this tall, handsome young Frenchman. He was so busy with researches on chemistry, hypnotism, the prevention of fires, the liting of cities, the aurora borealis and other subjects -- that he went on a diet of milk and bread to save time.

Besides his other activities, he spent six hours a day working at his laboratory furnace and once a week he spent the entire day in his laboratory.

Once he started to write a play, in addition to all his other activities, but he never finished the play.

When Lavoisier was only twenty-five, he was elected to the French Academy of Sciences. The next year, he became a tax farmer (a member of the organization which collected the taxes). Many tax farmers were greedy and dishonest, and the whole system was violently hated by the poor.

All the evidence we have proves that Lavoisier never did anything in the least dishonest and that he was genuinely interested in improving the lot of the poor. However, it turned out to be a sad thing for science that he ever joined the tax farmers, as you will soon see.

One good thing did result though -- he found a charming young wife, the daughter of another tax farmer, who became his lifelong companion and helper.

As previously pointed out -- oxygen, carbon dioxide and many other gases were discovered before Lavoisier studied them. Another French chemist, Jean Rey, had suggested long before that the gain in weight when objects burn in air was due to air "mixing" with the product.

John Black and Cavendish had carefully weighed the materials they experimented with and the products of the chemical change, which we call burning.

However, it was Lavoisier who made it plain that no matter that can be weighed disappears during any chemical change, and that if you weigh the products of any chemical change, you have exactly the same weight of matter that you started with.

This is the cornerstone of the whole modern science of chemistry.

Lavoisier also showed that burning and respiration are both forms of oxidation, one fast and the other slow, and that the whole phlogiston theory, or the idea of a substance with a weight less than nothing was unnecessary. He proved that diamond and charcoal are both forms of the same chemical element -- carbon.

Before Lavoisier's time the study of chemistry had been held back by a strange jargon of weird terms inherited partly from the ancients and the alchemists.

It was not always easy for one chemist to know just what the other was talking about. Our chemical language of today is largely to the work of these four. The words oxygen and hydrogen are inventions of Lavoisier's. A Frenchman, Louis Bernard Buyton de Morveau (1737-1816), was one of those who suggested to Lavoisier a simplified language of chemistry.

When Terror Cost Science Lost A Great Mind

Few scientists have had a happier life than Lavoisier. He was recognized throughout the world as one of the greatest scholars alive. He was happy in his married life and in his friends.

He was well-off financially. He was equally at home in the laboratory and in the company of the wits and social lions of Paris.

However as the French Revolution proceeded Lavoisier's connection with the tax farmers put him under suspicion.

One of the most bloodthirsty leaders in the revolutionary period we call the Reign of Terror was Marat, who had been belittled by Lavoisier years before as a very poor chemist.

This same Marat now attacked Lavoisier and helped to bring about his death by the guillotine in 1794, a month after Priestley had left England for America.