166 THE FLOATING-MATTEK OF THE AIR. 



turnip, never finding the least difficulty as to its steriliza- 

 tion. It is certain that the care bestowed in preparing 

 the turnip-infusion on the 20th of November, 1876, was 

 greater than that bestowed upon the same infusion in 

 1875. But whereas the latter was invariably sterilized 

 by five minutes' boiling, remaining afterwards as pel- 

 lucid as distilled water, the former, three days after its 

 preparation, became thickly turbid and swarming with 

 life. I extended the present inquiry to other substances 

 whose deportment was familiar to me last year, some of 

 whose infusions, indeed, still remain with me as clear as 

 they were on the day of their preparation. 



On the 1st of December, for example, infusions of 

 beef, mutton, pork, herring, haddock, and sole were 

 prepared, and introduced into six closed chambers, each 

 containing three tubes. On the 5th of December the 

 pork, beef, mutton, and haddock were all covered with 

 a fatty corrugated scum. A second chamber, containing 

 artichoke-infusion, prepared at the same time, was found 

 on the 5th more turbid than any of the animal infu- 

 sions, and equally covered with scum. In the animal 

 infusions, indeed, the body of the liquid underneath the 

 scum maintained a surprising brilliancy, the develop- 

 ment of life being confined to the layer in immediate 

 contact with the atmospheric oxygen. 



On the 5th of December the herring- and sole-infu- 

 sions were both clear ; but this was only a respite, for 

 on the 6th white spots appeared on the latter, which 

 extended until they covered the whole surface. The 

 herring-infusion remained clear for a week, after which 

 small specks began to appear on its surface. They 

 never reached the development of the scum which 

 coated the other infusions. It sometimes occurred to 

 me that the oil of this fish exercises a certain antiseptic 

 action. 



