. Carnegie Institution of Washington publication. THERMAL RELATIONS. 8l the germicidal action of the metal might arise. In no case should the cultures be incubated in the tin tubes. When exposures are made in test-tubes of resistant Jena glass, the cultures must be lowered into the liquid air gradually, the fluid being frozen from the bottom upward to avoid cracking the tubes. It requires about four minutes to properly freeze a culture in a glass test-tube. Large volumes of culture media should not be lowered into the liquid air, as it is wasteful, the air boiling away rapidly. The writer bega
. Carnegie Institution of Washington publication. THERMAL RELATIONS. 8l the germicidal action of the metal might arise. In no case should the cultures be incubated in the tin tubes. When exposures are made in test-tubes of resistant Jena glass, the cultures must be lowered into the liquid air gradually, the fluid being frozen from the bottom upward to avoid cracking the tubes. It requires about four minutes to properly freeze a culture in a glass test-tube. Large volumes of culture media should not be lowered into the liquid air, as it is wasteful, the air boiling away rapidly. The writer began his experiments with block-tin tubes, as shown in fig. 67, but now uses tubes of Jena glass. The latter crack occasionally in spite of Fig. 67.* For very rapid freezing the amount of fluid in the tube may be reduced to i cc. Liquid air in Dewar glasses, and compressed oxygen, hydrogen, and carbon dioxide (?) in steel cylinders may be had from the Eagle Oxygen Company, Incorporated, 121 West Eighty-ninth Street, New York City. The tanks of compressed gases may be bought or rented. The following sizes may be had : Fifty gallons (280 pounds pressure per square inch) ; 100 gallons (240 pounds pressure) ; 150 gallons (225 pounds pressure) ; and 200 gallons (280 pounds pressure). Cylinders may also be had with the gas under much greater pressure. The cost of the oxygen is 2 y> cents *Fic. 67.—Dewar glass for liquid air, and block-tin test-tubes used in first low temperature ex- periments with bacteria. About one-sixth actual Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Carnegie Institution of Washington. Washington, Carnegie Institution of Washington
Size: 1713px × 1459px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorcarnegie, bookcentury1900, bookdecade1900, bookyear1905
