io8 PASTEUR 



tion towards the problems of fermentation. A German 

 firm of manufacturing chemists, of whom there were 

 many in the neighbourhood of Strasbourg, noticed 

 that impure commercial tartrates of lime, when in 

 contact with organic matter, fermented if the weather 

 were warm. Pasteur tested this, and found that, when 

 racemic acid is fermented under ordinary conditions, 

 it is only the right-handed variety that is affected ; 

 and he suggests that this is probably the best way in 

 which to prepare the left-handed acid. 



Before dealing with Pasteur's work on fermentation 

 it is well to recall how the matter stood when he 

 began to study it. From the earliest period fermen- 

 tation had attracted the attention of mankind, but the 

 first record of an attempted explanation is that of 

 Basilius Valentinus, a Benedictine monk and alchemist, 

 who lived at Erfurt during the latter half of the 

 fifteenth century. He was, perhaps, more of a phar- 

 macologist than a chemist, but we owe to him the 

 introduction of hydrochloric acid, which he made from 

 oil of vitriol and salt. In his view alcohol existed in 

 the wort before fermentation began, and fermentation 

 was a process of purification of this alcohol, in which 

 the yeast played the part of the impurities. About a 

 century later van Helmont, a well-to-do physician of 

 Vilvorde, near Brussels, a kind of regenerate Para- 

 celsus, noted that when fermentation occurs 'gas' is 

 set free. It was van Helmont, indeed, who invented 

 the word ' gas.' Of the half-dozen words invented by 

 man — not derived, but created — ' gas ' is the one which 

 has most surely come to stay. Curiously enough, 

 van Helmont's predecessor, Paracelsus, also invented 

 two words which have, without the permanency of 'gas,' 

 passed into current, though somewhat infrequent, use. 

 They are ' gnome ' and ' sylph,' the latter, perhaps, 

 best known as recalling the outline of Miss Henrietta 

 Petowker in her palmier days. By his new term 



