The life of Pasteur

by René Vallery-Radot

Pasteur would have liked Raulin to come with him to London in September, 1871, before settling down in Paris.

The Chamalières brewery was no longer sufficient for Pasteur; he wished to see one of those great English breweries which produce in one year more than 100,000 hectolitres of beer. The great French savant was most courteously received by the managers of one of the most important breweries in London, who offered to show him round the works where 250 men were employed. But Pasteur asked for a little of the barm of the porter which was flowing into a trough from the cask. He examined that yeast with a microscope, and soon recognized a noxious ferment which he drew on a piece of paper and showed to the bystanders, saying, “This porter must leave much to be desired,” to the astonished managers, who had not expected this sudden criticism. Pasteur added that surely the defect must have been betrayed by a bad taste, perhaps already complained of by some customers. Thereupon the managers owned that that very morning some fresh yeast had had to be procured from another brewery. Pasteur asked to see the new yeast, and found it incomparably purer, but such was not the case with the barm of the other products then in fermentation—ale and pale ale.

By degrees, samples of every kind of beer on the premises were brought to Pasteur and put under the microscope. He detected marked beginnings of disease in some, in others merely a trace, but a threatening one. The various foremen were sent for; this scientific visit seemed like a police inquiry. The owner of the brewery, who had been fetched, was obliged to register, one after another, these experimental demonstrations. It was only human to show a little surprise, perhaps a little impatience of wounded feeling. But it was impossible to mistake the authority of the French scientist’s words: “Every marked alteration in the quality of the beer coincides with the development of micro-organisms foreign to the nature of true beer yeast.” It would have been interesting to a psychologist to study in the expression of Pasteur’s hearers those shades of curiosity, doubt, and approbation, which ended in the thoroughly English conclusion that there was profit to be made out of this object lesson.

Pasteur afterwards remembered with a smile the answers he received, rather vague at first, then clearer, and, finally—interest and confidence now obtained—the confession that there was in a corner of the brewery a quantity of spoilt beer, which had gone wrong only a fortnight after it was made, and was not drinkable. “I examined it with a microscope,” said Pasteur, “and could not at first detect any ferments of disease; but guessing that it might have become clear through a long rest, the ferments now inert having dropped to the bottom of the reservoirs, I examined the deposit at the bottom of the reservoirs. It was entirely composed of filaments of disease unmixed with the least globule of alcoholic yeast. The complementary fermentation of that beer had therefore been exclusively a morbid fermentation.”

When he visited the same brewery again, a week later, he found that not only had a microscope been procured immediately, but the yeast of all the beer then being brewed had been changed.

Pasteur was happy to offer to the English, who like to call themselves practical men, a proof of the usefulness of disinterested science, persuaded as he was that the moral debt incurred to a French scientist would in some measure revert to France herself. “We must make some friends for our beloved France,” he would say. And if in the course of conversation an Englishman gave expression to any doubt concerning the future of the country, Pasteur, his grave and powerful face full of energy, would answer that every Frenchman, after the horrible storm which had raged for so many months, was valiantly returning to his daily task, whether great or humble, each one thinking of retrieving the national fall.

Every morning, as he left his hotel to go to the various breweries which he was now privileged to visit in their smallest details, he observed this English people, knowing the value of time, seeing its own interests in all things, consistent in its ideas and in its efforts, respectful of established institutions and hierarchy; and he thought with regret how his own countrymen lacked these qualities. But if the French are rightly taxed with a feverish love of change, should not justice be rendered to that generous side of the French character, so gifted, capable of so much, and which finds in self-sacrifice the secret of energy, for whom hatred is a real suffering? “Let us work!” Pasteur’s favourite phrase ever ended those philosophical discussions.

He wanted to do two years’ work in one, regardless of health and strength. Beyond the diseases of beer, avoidable since they come from outside, he foresaw the application of the doctrine of exterior germs to other diseases. But he did not allow his imagination to run away with him, and resolutely fixed his mind on his present object, which was the application of science to the brewing industry.

“The interest of those visits to English breweries,” wrote Pasteur to Raulin, “and of the information I am able to collect (I hear that I ought to consider this as a great favour) causes me to regret very much that you should be in want of rest, for I am sure you would have been charmed to acquire so much instruction de visu. Why should you not come for a day or two if your health permits? Do as you like about that, but in any case prepare for immediate work on my return. We need not wait for the new laboratory; we can settle down in the old one and in a Paris brewery.”

When Pasteur returned to Paris, Bertin, who had not seen him since the recent historic events, welcomed him with a radiant delight. School friendships are like those favourite books which always open at the page we prefer; time has no hold on certain affections; ever new, ever young, they never show signs of age. Bertin’s love was very precious to Pasteur, though the two friends were as different from each other as possible. Pasteur, ever preoccupied, seemed to justify the Englishman who said that genius consists in an infinite capacity for taking pains; whilst Bertin, with his merry eyes, was the very image of a smiling philosopher. In spite of his position as sub-director, which he most conscientiously filled, he was not afraid to whistle or to sing popular songs as he went along the passages of the Ecole Normale. He came round to Pasteur’s rooms almost every evening, bringing with him joy, lightness of heart, and a rest and relaxation for the mind, brightening up his friend by his amusing way of looking at things in general, and—at that time—beer in particular.