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Interpretation of deviations from Ohm's law
A THERMOSCOPE FOR LIQUID-AIR BATHS.* BY
ENOCH KARP~I~ Ph.D. The Cleveland Wire Works, General Electric Company; Member of the Institute.
A SIMPLE device for observing and controlling lowtemperature baths makes use of the absorption properties o f FIG. i.
C~arcoo ]
charco~ at low temperature. A tube partially filled with granular charcoal and a gas is connected to a manometer (a simple U-tube * Communicatedby the Author. 8o9
8IO
ENOCH KARRER.
[J. F. I.
with mercury). The mercury surfaces will be displaced dewnding upon the amount of the gas that is held by the charcoal; that is, upon the temperature of the charcoal. One may choose the range of greatest sensitivity by properly selecting the gas that is in contact with the charcoal. A specific case is sketched in Fig. I, where argon is used in the charcoal chamber. The pressure of the argon is about 2o cm. when the charcoal is at room temperature. The space above the mercury in the other limb of the manometer is evacuated. The temperature range over which this particular thermoscope indicated is near and slightly above the boiling-point of argon. This argon-filled thermoscope has been enaployed over an extended interval for the control of the temperature ill a purifying system for helium and neon. In this system the space containing the purifying charcoal was annular, made by welding together concentrically two steel cylinders. The charcoal chamber of the thermoscope was inserted into the inner cylinder. During the routine manipulation the liquid-aid baths surrounding the purifying charcoal chambers were allowed to warm up until the mercury surface in the thermoscope began to move. Such a thermoscope may be transformed into a real thermometer by attention to design, and also into an automatic controlling device since electrodes may be sealed in and a relay operated through it. It may be of service in other lines than that mentioned, where other materials than charcoal and argon with selective porosity and organic vapors are concerned. My thanks are due Messrs. A. Poritsky and John Birdsell for making and filling thermoscopes and to Mr. W. Eppinger for faithfully trying them out and using them in the production of helium and neon. CLEVELAND, OHIO, May 25, I926.
Poisoning by Mercury Vapor.--L. M. DENNIS,Of Cornell University (Ind. and Eng. Chem., 1926, IS, I2O5) , calls attention to the occurrence of chronic mercury poisoning as a result of inhalation of mercury vapor. He recommends that the floor of the laboratory be free from cracks, that spilled mercury should not be permitted to lie in the room, that all containers of mercury be covered Or stoppered when not in use, that ventilation be efficient and thorough, and that work with open mercury be conducted in a hood whenever possible. J.S.H.
ENOCH KARP~I~ Ph.D. The Cleveland Wire Works, General Electric Company; Member of the Institute.
A SIMPLE device for observing and controlling lowtemperature baths makes use of the absorption properties o f FIG. i.
C~arcoo ]
charco~ at low temperature. A tube partially filled with granular charcoal and a gas is connected to a manometer (a simple U-tube * Communicatedby the Author. 8o9
8IO
ENOCH KARRER.
[J. F. I.
with mercury). The mercury surfaces will be displaced dewnding upon the amount of the gas that is held by the charcoal; that is, upon the temperature of the charcoal. One may choose the range of greatest sensitivity by properly selecting the gas that is in contact with the charcoal. A specific case is sketched in Fig. I, where argon is used in the charcoal chamber. The pressure of the argon is about 2o cm. when the charcoal is at room temperature. The space above the mercury in the other limb of the manometer is evacuated. The temperature range over which this particular thermoscope indicated is near and slightly above the boiling-point of argon. This argon-filled thermoscope has been enaployed over an extended interval for the control of the temperature ill a purifying system for helium and neon. In this system the space containing the purifying charcoal was annular, made by welding together concentrically two steel cylinders. The charcoal chamber of the thermoscope was inserted into the inner cylinder. During the routine manipulation the liquid-aid baths surrounding the purifying charcoal chambers were allowed to warm up until the mercury surface in the thermoscope began to move. Such a thermoscope may be transformed into a real thermometer by attention to design, and also into an automatic controlling device since electrodes may be sealed in and a relay operated through it. It may be of service in other lines than that mentioned, where other materials than charcoal and argon with selective porosity and organic vapors are concerned. My thanks are due Messrs. A. Poritsky and John Birdsell for making and filling thermoscopes and to Mr. W. Eppinger for faithfully trying them out and using them in the production of helium and neon. CLEVELAND, OHIO, May 25, I926.
Poisoning by Mercury Vapor.--L. M. DENNIS,Of Cornell University (Ind. and Eng. Chem., 1926, IS, I2O5) , calls attention to the occurrence of chronic mercury poisoning as a result of inhalation of mercury vapor. He recommends that the floor of the laboratory be free from cracks, that spilled mercury should not be permitted to lie in the room, that all containers of mercury be covered Or stoppered when not in use, that ventilation be efficient and thorough, and that work with open mercury be conducted in a hood whenever possible. J.S.H.