Note 20 — Chapter II · On the Causes of the Diseases which affect Beer and Wort.

In these experiments the asbestos is only introduced by way of extra precaution. Originally, in his early experiments in connection with the subject of spontaneous generation, the results of which were published in 1860-62, the author did not use it, and he observed no ill effects resulting from the omission; now, however, he constantly makes use of it. In studies of this kind novel precautions are never thrown away; moreover, the presence of this asbestos is a sure bar to the entrance of insects. The author has preserved for a long time a flask, in the slender neck of which an insect is contained; he killed it with a flame just as it was approaching the liquid. Quite recently, M. Calmettes, a young engineer from the École Centrale, when engaged, at Tantonville, in Tourtel’s brewery, in carrying out certain practical experiments in connection with the process that will he described in one of the later chapters of this work, wrote complaining that his flasks had been suddenly invaded by a swarm of aphides, scarcely larger than phylloxeras, and that many of them had even penetrated into the inside of the curved tubes.