642 THE POPULAR SCIENCE MONTHLY. 



sows. I say that the inference that his crop is the product of the 

 seeds that he sows is not more certain than the inference that those 

 crops produced in the organic infusions are due to the seeds contained 

 in them. 



You know the method that we resorted to for the purpose of 

 enabling us to get rid of this dust. The object was, to allow the air 

 to purify itself, and it was done in this way : I have here the first 

 chamber that was used in these experiments. You see at the bottom 

 a series of test-tubes entering the chamber; they are air-tight, and 

 they open into it. There are windows at the sides, and here is a 

 pipette through which the liquids can be introduced. Behind we 

 have a door which opens upon its hinges. Now, imagine this per- 

 fectly closed ; imagine it abandoned entirely to itself, left perfectly 

 quiet. In a few days, the floating dust of the air contained in the 

 chamber entirely disappears it has removed itself by its own subsi- 

 dence and then, when you send a beam of light such as we have 

 here through these windows, you see no track of the beam within the 

 chamber. When the air is in this condition, you pour through this 

 pipette infusions of beef, mutton, or vegetables, into these tubes, and 

 allow them to be acted upon by the air. Last year, between fifty 

 and sixty of these chambers were constructed, and the invariable 

 result was that these infusions never putrefied, never showed any 

 change, were perfectly sweet months after they were placed there, as 

 long as the air had this floating matter removed. You had nothing 

 to do but to open the back-door and allow the dust-laden air to enter 

 the chamber to cause these infusions to fall into a state of putrefaction, 

 and swarm with microscopic life, in three days after opening the door. 

 I have a smaller chamber here for we use chambers of different sizes 

 and it will enable you to understand our exact process. (See Fig. 

 1.) You see here the stand on which the chamber rests. There are 

 two bent tubes that communicate with the outer atmosphere, for I 

 wish to have a free communication between the air outside and the 

 air within. You see the pipette through which the tube is filled. 

 When the infusion is poured in, you place it in an oil-bath contained 

 in a copper vessel, such as we have here, in which you boil it for five 

 minutes. Now, that boiling for five minutes was found capable of 

 sterilizing every germ contained in the infusions placed in these cham- 

 bers. This year our experiments began by a continuation of those 

 that we made last year. In' order to enable you to judge of the 

 severity of the results obtained last year, I have here five cases belong- 

 ing to the experiments then made. You will see that the infusions 

 are vastly concentrated because of their slow evaporation. The 

 quantity of liquid is reduced to one-fifth of its primitive volume, but 

 this one-fifth is as clear as rock-crystal; whereas, the tubes exposed 

 to the ordinary air outside fell long ago into utter putrefaction. They 

 became turbid and covered with scum, and when you examine these 



