SPONTANEOUS GENERATION. 



485 



five hours we pour off the liquid, boil it, filter it, and obtain an infu- 

 sion as clear as filtered drinking-water. We cool the infusion, test 

 its specific gravity, and find it to be 1006 or higher water being 

 1000. A number of small, clean, empty flasks, of the shape here 

 shown, are before us. One of them is slightly 

 warmed with a spirit-lamp, and its open end is 

 then dipped into the turnip-infusion. The 

 warmed glass is afterward chilled, the air 

 within the flask cools, contracts, and is followed 

 in its contraction by the infusion. Thus we 

 get a small quantity of liquid into the flask. 

 We now heat this liquid carefully. Steam is 

 produced, which issues from the open neck, 

 carrying the air of the flask along with it. 

 After a few seconds' ebullition, the open neck 

 is again plunged into the infusion. The steam 

 within the flask condenses, the liquid enters to supply its place, and 

 in this way we fill our little flask to about four-fifths of its volume. 

 This description is typical ; we may thus fill a thousand flasks with 

 a thousand different infusions. 



I now ask my friend to notice a trough made of sheet-copper, 

 with two rows of handy little Bunsen burners underneath it. This 

 trough, or bath, is nearly filled with oil ; a piece of thin plank consti- 

 tutes a kind of lid for the oil-bath. The wood is perforated with 

 circular apertures wide enough to allow our small flask to pass 

 through and plunge itself in the oil, which has been heated, say, to 

 250 Fahr. Clasped all round by the hot liquid, the infusion in the 

 flask rises to its boiling-point, which is not sensibly over 212 Fahr. 

 Steam issues from the open neck of the flask, and the boiling is con- 

 tinued for five minutes. With a pair of small brass tongs an assist- 

 ant now seizes the neck near its junction with the flask, and partially 

 lifts the latter out of the oil. The steam does not cease to issue, but 

 its violence is abated. With a second pair of tongs held in one hand, 

 the neck of the flask is seized close to its open end, w r hile with the 

 other hand a Bunsen's flame or an ordinary spirit-flame is brought 

 under the middle of the neck. The glass reddens, whitens, softens, 

 and as it is gently drawn out the neck diminishes in diameter, until 

 the canal is completely blocked up. The tongs with the fragment of 

 severed neck being withdrawn, the flask, with its contents diminished 

 by evaporation, is lifted from the oil-bath perfectly sealed hermeti- 

 cally. 



Sixty such flasks filled, boiled, and sealed, in the manner described, 

 and containing strong infusions of beef, mutton, turnip, and cucum- 

 ber, are carefully .packed in saw-dust and transported to the Alps. 

 Thither, to an elevation of about 7,000 feet above the sea, I invite my 

 co-inquirer to accompany me. It is the month of July, and the 



