Klacel found the candle and the matches and the monks huddled in their own circle of light as they gingerly felt their way along a cold stone floor in the direction of the voice. As they drew near they could see that the wine maker was drawing small samples of wine from a series of oak casks and placing them in none too clean wine glasses for later testing.
"Ahoj," he said to them as they stopped by his table, "what brings you here?"
"We think we may have an answer to the souring of your wine," Mendel said with a shiver and rubbed his hands across his shoulders. Even through his thick coat he could feel the damp of the wine cellar.
"Oh, yes," Hola Teplinka sniffed. He had learned the art of making wines from his father, who had learned from his father who had learned from his father. There was nothing he did not know about turning grape juice into superb alcoholic beverages, and certainly he could learn nothing new from three monks.
"We think so," said Mendel, sensing the skepticism. "There appear to be bacterius organisms growing in your burack, and it is the metabolic activity of these contaminants that is spoiling your wine." As often happened, Mendel's scientific explanation sounded like a foreign language to his audience.
"Indeed," said Teplicka, lifting one of his samples and putting it near the candle flame. It glowed red and full. Now that was wine of the first rank!
"We will need your help to try and correct the problem," said Mendel stiffly, the cold on his back was becoming distinctly uncomfortable. "Could we go somewhere warmer so that we could discuss it?"
"Must finish this before I leave," said Teplicka, tapping a glass and bending down to get another one.
"Could you at least listen to what we have to say? We have worked very hard on this problem for Herr Druer and we would like your expert opinion," said Klacel in Czech. His voice was sharp but still friendly. Whether it was the fact that he had been addressed in his own language, or whether it was the fact that he respected Brother Matthew, he could not say, but Herr Teplicka put down his glass and picked up his candle.
"Over here," he said and walked off without waiting.
To their great relief the vintner led them out of the cellar, up some well worn stairs and into a small room at ground level that was comfortably warmed by a pot-bellied stove.
"Turecka?" he asked and pointed to what passes as coffee in most Czech households. Although he optimistically called his brew 'Turkish', Hola Teplicka made his coffee by simply passing hot water over coffee grounds. He then drank it black without milk or sugar. Mendel wisely declined but Brother Joseph and Brother Matthew enthusiastically accepted.
"We have something we want to tryout, and we want to use some of the sour wine," Klacel said when they had been served and were sitting at Teplicka's table. "As Brother Gregory just told you, we think we know why some grape juices ferment into wine and why some go sour. We think it is because of tiny organisms, so small you can only see them by using a microscope, that live in the grape juice and transform the sugars into either alcohol or sauerstoff. If we are right we may have found a way of stopping the souring process and rescuing the fermentation before it spoils completely."
"There has never been a way of stopping a 'souring' once it has started," Teplinka grunted and took another sip of his coffee. "In all my years I have never seen it happen, and never will."
"Perhaps we can show you otherwise," said Klacel gently.
"Doubt it," was the answer, but it was not completely negative.
"At least let us tell you what we think," said Klacel and hurried on before the wine maker could object.
"We need to do two things," he said, "first we need to kill or slow down the bacterius organisms. This will prevent the wine from souring further. Then we need to encourage the yeast cells to grown once more and make alcohol. You gave us the first clue as to how to stop the souring." He paused, but the wine maker did not respond to the flattery.
"Sulfur seems to be the key," he went on, "when sulfur is burnt in the air it combines with elements in the air to form a compound that kills the bacteria. We think this sulfur compound is a combination of the yellow sulfur with oxygen from the air. Some call it 'sulfur oxide', but by any name it seems to be effective."
"So that is why sticks of sulfur must be burned in the wine casks before the fermentation begins," said Mendel. "You told us that yourself, and that was the stage omitted by Herr Druer. When the grape juice was added to the untreated flasks, the bacteria organisms simply out grew the yeast organisms and the wine turned sour."
"We would like to try killing these bacteria by adding back extra 'sulfur oxide' to fermentations in your barrels," said Klacel.
"You can't burn sulfur under water," Teplinka snorted. It had been a mistake listening to these scientists, they were never practical.
"But we have found a form of sulfur that is already in the right form, all we have to do is add a little to your wine and wait to see if it kills the bacteria," replied Klacel putting a hand in his pocket. "The apothecary called it 'devils sulfur', but it seems to contain the necessary active ingredients. We have tested it in our experiments and it seems to kill bacteria in our bottles, but we now want to try it in a proper barrel of wine."
Brother Matthew never knew, but the form of sulfur he had been given by the apothecary would one day be called potassium metabisulfate, a chemical that releases sulfur dioxide in high yields when dissolved in wine. This bactericide is still used today.