Louis Pasteur (1822-1895) in 1886.

In September 1854, Louis Pasteur is named Professor and Doyen of the new Faculty of Sciences in Lille.  In this institution, the pupils, having paid a small amount of money, have access to the laboratories where they can repeat the principal experiments done in class.  Pasteur displays eloquence to attract numerous auditors to the Faculty:

“Where in your families do you find a single young man whose curiosity and interest are not immediately woken when you place a potato in his hands, and with it he can make sugar, with this sugar, alcohol, with this alcohol, ether and vinegar?  Who would not be happy to tell his family in the evening that he has just made an electric telegraph work?”

What would lead Pasteur from crystals to yeasts, from yeasts to bacteria, finally from bacteria to vaccine, is doubtless born of the relations that he formed at this epoch with the industrial world.  Leading “scholarly caravans”, the Professor takes his students into foundries and factories at Aniche, Denain, Saint-Omer and Valenciennes, and questions continuously.  Not only does he want to place Science at the service of the Industrialists, but he thinks that, to feed itself, Science must find economical applications, rapidly preferably, if not immediately.  He invents therefore what we would call today Applied Science:  an Industrialist solicits him and he installs for the first time a laboratory in a factory.  He says:

“Without the theory, the practice is only the routine given by habit.  Only the theory can make the spirit of invention surge and develop.”

Under the scholar’s impulsion, the Lille Faculty passes in notoriety that of Lyon, the Pasteur Revolution is underway.


One day, the son of an Industrialist talks about the accidents which happened during the Summer of 1856 during the manufacture of beetroot alcohol in the factory of his father, Monsieur Bigo, where numerous fermentations turned out to be defectuous, the beetroot juice not being transformed into alcohol.  Pasteur’s microscope enters into action, along with his polarimetre.  Pasteur observes the beetroot juice.  Something is intriguing him.  The laboratory is not succeeding in imitating Nature.  There is a natural fermentation and a laboratory fermentation.  In fact, the Professor is on the point of making a discovery which will shake the Chemistry world…  We must understand that, at this epoch, the most total obscurity surrounds the phenomenon of fermentations – the transformations are done in the Industry most often in an empiric fashion.  The potato and the beetroot only become alcohol and vinegar if a certain number of particular conditions are present, but the intimate mechanics of this metamorphosis is not yet known.

For months and months, the untiring scientific detective would verify that he has not made a mistake:  Nature conserves the power to make polarized light turn in the fermented substances that he is studying, the laboratory does not.  Why?…  In natural fermentation, he is going to see the intervention of a small living mould:  yeast.

“Louis is plunged up to his neck in beetroot juice”,

his wife would write to her father-in-law.  To this beetroot juice, Louis adds chalk, sulphur, phosphorus…  When the conditions are good, the yeasts develop and the fermentation accelerates:  each mould only sprouts if it finds what it needs to renew itself, “food”, as it were.

What Pasteur is claiming comes in total contradiction with what is thought by the principal Scientists of his epoch, like the German Justus Von Liebig.  He considers that the little mould is one of the results of fermentation.  Pasteur demonstrates, on the contrary, that it is its cause, then he shows that the yeast can be dried, reduced to powder and conserved like this without losing its faculty of reproduction.

“This little cellular plant can exist in a fecund state in the air and in dust.”

This passing swipe is aimed at the heterogenists.  All that is left is to put together the two techniques that he masters, that of crystals and that of fermentations.  On 21 December 1857, he announces to the Academy that he has discovered a mode of fermentation of tartric acid:  the yeasts eat the right acid and degrade it and make it ferment, but do not attack the left.

“The yeasts are very singular table guests for whom the disposition of the serving dishes on the table has more importance than their chemical nature.”

In October 1857, he is named Administrator of the Ecole normale superieure, and Director of Scientific Studies.  But he will fail;  he is not made for Administration.  His lack of diplomacy, his comportment, which is at the least authoritative, offend the Normaliens, the students are agitated under his rule, and he will return to his cherished studies, his charge being abolished by the Minister of the epoch.


Pasteur is anxious to return to his studies on wines.

“Could the diseases of wines come from organized ferments, little microscopic vegetals whose germs would develop according to certain circumstances of temperature, atmospheric variations, exposure to air which would allow their evolution or their introduction into the wine?…  I arrived in fact at this result, that the alterations of wines are correlative to the presence and the multiplication of microscopic vegetals.”

It is an important question:  these national riches rapidly go bad and, consequently, cannot be exported.  With his little troup, Pasteur settles in Arbois to study the new wines.  The Municipal Council proposes to cover the costs of the installation of a little laboratory for their local boy.  Pasteur gratefully thanks the Mayor in a brief speech full of emotion, but prefers to camp with his assistants in the back-room of a cafe, fearing not to be able to render a service in proportion to the generosity of the aediles.  The installation is extremely basic, the instruments of investigation are made locally.  Duclaux recounts:

“As the apparatus nearly all came from the Carpenter, the Tinsmith or the Blacksmith of Arbois, one can guess that they did not have state of the art forms and that, when we carried them into the street, to go to draw wine from the cellars destined for the analyses, we never passed without raising a few jeering remarks in the rather mocking population of the little town.”

For the scholar, the problem is reduced to opposing the development of the organized ferments or parasitic vegetals, the cause of the malady of the wine.  He therefore notes, after several unsuccessful attempts, that it is enough to bring the wine for a few instants to a temperature of 50 or 60 degrees Centigrade.  That is all.  The procedure is extremely simple to do.

“I note that the wine is never altered by this preliminary operation, and as there is nothing to prevent it still being submitted to the gradual action of the oxygen in the air, the more or less exclusive source, in my opinion, of its improvement over time, it is evident that this procedure unites the most advantageous conditions.”

The scientific problem solved, Pasteur’s greatest concern is to have the whole country benefit from his discovery.  But French viticulture is not ready to hear this sort of discourse, and retrenches behind its traditions, rejecting the principle of the heating of wine.  The harvests therefore continue to be spoiled in the casks and in the bottles.  It is the Navy which will change the course of History, loading onto its ships casks of heated wine.

To be continued.