FUNGI AND MODERN AFFAIRS — RAMSBOTTOM 321 



the War of 1914-18, the Germans were short of glycerol for making 

 explosives. Neuberg, in 1911, had begun to publish his studies on the 

 stages leading to alcohol formation by yeast. When experimenting 

 on aldehyde fixation with sodium sulphite, there was a large increase 

 in the percentage of glycerol. Connstein and Liidecke successfully 

 applied this to large-scale production ; many will remember the wild 

 guesses that were made at the time concerning the source of the en- 

 emy's glycerine. They produced 1,000 tons a month by the method, 

 the average yield being 20 to 25 percent of the sugar used, and in 

 addition large quantities of alcohol and acetaldehyde were obtained 

 as byproducts. It has been said that it enabled the Germans to carry 

 on the war for another 12 months. The Americans, hearing that gly- 

 cerine was being produced by yeasts, succeeded in devising a couple 

 of similar processes. H. Raistrick and his colleagues, after 1918, used 

 a modified sulphite process at Nobel's factory at Ardeer and increased 

 the yields of glycerine in the fermentation liquor to 35 to 40 percent 

 of the weight of sugar fermented. Subsequent improvements in the 

 methods of recovery of glycerine from the fermentation liquors have 

 reduced the cost of fermentation glycerine to a figure comparable with 

 that of soap lye glycerine. 



One of Pasteur's statements, "We are convinced that a day will come 

 when molds will be utilized in certain industrial operations, on account 

 of their power of destroying organic matter", 3 in spite of its definite- 

 ness, was generally disregarded. However, his favorite pupil, van 

 Tieghem, established the importance of molds in the biochemical field. 

 He investigated the method of production of gallic acid from heaps of 

 vegetable matter containing tannin — gall nuts, sumach, tea, etc. — 

 watered and allowed to go moldy. He showed in 1867 that the mold 

 principally concerned is Aspergillus niger. The present-day method 

 of production is to inoculate clear tannin extract with this fungus. 



It was not until 1893 that the first real advance was made, when 

 Wehmer described the production of citric acid by two species of 

 Penicillium {Citromyces) grown in nutrient sucrose solutions con- 

 taining calcium carbonate. It has been found that a number of molds 

 produce citric acid, but the one used on a commercial scale is Asper- 

 gillus niger. In 1922, Italy produced about 90 percent of the world's 

 supply of calcium citrate from citrous juices, but within 8 years the 

 export had practically stopped because of the commercial production 

 by molds — 10,000,000 pounds annually in the United States alone. 

 There is now an International Citric Acid Agreement. 



The process is a surface fermentation of a nutrient sucrose solution, 

 with a comparatively large amount of mineral acid which prevents 

 the growth of bacteria and most molds. The solution is seeded with 



3 Pasteur, L., Studies on fermentation. English translation, p. 261, 1879. I am 

 indebted to Dr. J. Yuill for directing my attention to this. 



