Louis Pasteur (1822-1895) in 1886.

Curiously, it is in Italy that the utility of Pasteur’s method of raising silkworms will be demonstrated.  In Italy and in a private Parisian study whose high windows open onto the Place du Carrousel.  There, an old soldier, Field-Marshal Vaillant, Minister of the House of the Emperor, raises silkworms in the heart of Paris and verifies the merits of Pasteur’s procedure.  Convinced, he decides to take the scholar to finish his convalescence in Trieste in a magnanery whose production of silk cocoons has been nil for ten years.  Under the direction of its inventor, the Pasteur Method then performs marvels, and at last, in the Centre of Production’s Accounts Ledger, in the column which has been empty for ten years, the sum of 22,000 francs is written, the nett profit from the sale of cocoons from silkworms, at last productive and in perfect health.  Pasteur takes advantage of this calmer period to write a treatise on his procedure.  High Italy and Austria adopt the system, France would end up following.

A good many years later, in 1882, he would be acclaimed by the little town of Aubenas, in Ardeche.  The Municipality would make him a gift of a little microscope – that microscope of which it was said that no magnanery would know how to use it.  The President of the Spinners’ Syndicate would say at the time to him:

“For us all, you were the helpful genie whose magical intervention removed the spell of the plague that was ruining us.  It is the benefactor that we salute in you.”

In fact, during these four years, the Chemist Pasteur will have progressed in the understanding of living beings, and gleaned along the way a whole sum of information which will take on all its sense a few years later with vaccination.  He was able to observe that the visible corpuscules in the sick silkworm moths totally lose their faculty for contagion by exposition to air and through dessication.

The 1870 War erupts, the Museum of Natural History is bombarded, Val-de-Grace Hospital is under fire from Prussian cannons, l’Ecole normale is partially destroyed;  there is fighting in Paris.  Pasteur and his family then leave the capital for Arbois.  Gradually, the cannon noise moves away and work will start again.  Pasteur remarks:

“The War put my brain out to pasture.”


Pasteur writes to Claude Bernard:

“I have decided to go with my family to settle for a few months near Clermont-Ferrand close to my dear Duclaux, at Royat.”

Pasteur joins his pupil who has become a Professor of Chemistry at the Faculty of Clermont.  Duclaux sets up a little laboratory for him.  But between Royat and Clermont, there is Chamalieres and its Beer Brewery.  Like wine, beers “become troubled, acidic, turn bad, runny or putrid”.  Pasteur is then animated by patriotic sentiments:  German beer, in fact, is largely superior to French beer.  He wants to free his country from its importations by finding an answer, that is to say, by isolating the good yeast.  After crystals and silkworms, he studies fermentations.  The same scenario as that of the tartrate occurs again:  he goes to visit Breweries in England where the samples of beer are observed under the microscope, then taken from the greatest Parisian cafes, as well as in the Brewery of the Tourtel Brothers, in Nancy.  In this periple, he is accompanied by Bertin, a former companion at the Ecole normale, and joyful gastronomist.  Bertin tries to convince his friend that beer should not be considered exclusively as a fermentation problem, but that it can also procure great joys…  Pasteur smiles and bends over his microscope.  He notices that quality yeast is obtained more or less by chance;  if a fermentation fails, the Brewer procures other primary materials, with all the dangers of contamination represented by transports between Breweries, between cities, between countries.  The study begins.  The balloons are seeded, they are heated to 20 degrees Centigrade, 60 degrees Centigrade.  In 1875, after five years of experiments, it is the publication of Etudes sur la biere et les conseils aux brasseurs.  The principle would be:

“It is necessary that the sweetened wort [that is to say, the future beer, not yet fermented] be exempt from impureties and that the air which is continuously renewed on the surface of the liquid always arrive pure…”

The Chemist shows that there are good and bad yeasts in the fermentation wort.  He proposes therefore to the Brewers to remove all the yeasts, before seeding them exclusively with the good ones.  To finance his research, he becomes an Engineer and deposits the Patent for an apparatus for the sterilization of the beer wort.  Pasteur rejoices to see that the Brewers accept his process without reticence, and that the Jacobsens have created in Carlsberg “a laboratory destined exclusively to progress in the art of brewing”.

Then the scholar tries his hand at Politics, for the Senate Elections, with a programme which can be summed up almost in one sentence:

“Science at the service of the citizen.”

It’s a bit short, and the voters send him back to his test-tubes.  His nephew, Adrien Loir, proposes an amusing explanation for this defeat:

“Pasteur had the phobia of shaking hands, and that is probably what made people think that he was haughty.  […]  In the light of his principles [of hygiene], he was sparing with his handshakes.  It is perhaps for this, and also for other reasons that, in 1876, he failed when he presented himself for election to the Senate in the Jura.”


To be continued.