THE BOUQUET OF WINE 113 



converts alcohol into acetic acid ; and he taught the 

 manufacturers the importance of pure cultures, show- 

 ing them how, by a careful manipulation of the 

 temperature, and by artificially sowing the fungus 

 which effects the chemical change, the product they 

 sought could be produced in a week or ten days, 

 instead of requiring two or three months. This 

 problem naturally led on to the acetous fermentation 

 of wine, the cause of great loss to French wine 

 exporters. Pasteur was able to demonstrate that 

 the sourness of wine is caused by various foreign 

 organisms, each of which causes a peculiar flavour 

 to appear in the wine it attacks. The bouquet of wine 

 is notoriously a delicate object, easily disturbed ; and 

 the question arose how to check the growth of the 

 organisms without interfering with the bouquet. 

 Pasteur solved it as he solved similar problems with 

 regard to milk. He was able to show that after wine 

 is properly oxygenated, if it be heated to a tempera- 

 ture of some 55° to 60° C. the acid-forming micro- 

 organisms are destroyed, whilst the bouquet is un- 

 affected. Perhaps one of Pasteur's greatest triumphs 

 was his success in demonstrating this to a repre- 

 sentative assemblage of wine-tasters, notoriously a 

 very opinionative class of people. 



Pasteur's researches on micro-organisms further 

 had a profound influence on operative surgery. To 

 the presence of bacteria is due many of the dangers 

 which used to follow on operations. If precautions 

 are taken to exclude the harmful germs much suffering 

 and danger are avoided. It was about this date — 

 namely, in the spring of 1865 — that Dr. (now Lord) 

 Lister, who nobly acknowledged the debt he owed to 

 Pasteur, performed his first operations under anti- 

 septic treatment at the Glasgow Infirmary. This date 

 marks an epoch in the history of human suffering. 



The chemist Dumas was about this time a member 



