Thermometers filled

Liquid-in-glass thermometers Bimetallic thermometers Filled-system thermometers Phase change... 

Fig. 6. (a) Three-necked flask fitted with thermometer, filling funnel, and propellor stirrer with gas-tight seal (b) three-necked flask fitted with reflux condenser, dropping funnel, and paddle stirrer with gas-tight seal. 

Quartz glass thermometers filled with mercury under pressure have been constructed to measure temperatures up to 750 C. They are not used in this country, however, except to a negligible extent. Reports as to their behavior have not been promising. 

For temperatures down to -200°C, organic liquids can be used as the working fluid. Thermometers filled with organic liquids, however, are not considered as reliable as mercury-filled thermometers. 

Resistance thermometers Filled-system thermometers Bimetal thermometers low temperatures... 

F = correction factor. For approximate work and when the liquid in the thermometer is mercury a value for F of 0.00016 is generally used. For more accurate work with mercury filled thermometers values as given in the following table are used. For thermometers filled with organic liquids it is customary to use 0.001 for the value of F. 

The ideal gas thermometer realized by limitation (A.l) may be looked upon as a thermometer filled by ideal gas which is defined by... 

Measurement of the dielectric constant, D, of dioxan/water mixtures Thermally equilibrate a IpF capacitance ceil filled with air in a thermostat for 20-30 minutes. Measure the capacitance Cq using a Universal Dielectrometer and record the temperature on a precision thermometer. Fill the cell with a calibrating liquid e.g water, whose dielectric constant, D,., is accurately known over a temperature range. Thermally equilibrate at the same temperature and then measure the capacitance, Q. Calculate the measuring capacitance. Cm, of the cell from the relation ... 

Secondary standards are liquid-in-glass thermometers and base-metal thermocouples. They are calibrated by comparing them with primary-standard platinum-resistance thermometers or standard platinum-rhodium versus platinum thermocouples at temperatures generated in comparators. These secondary standards are used in turn for the calibration of other devices, such as liquid-in-glass thermometers, bimetallic thermometers, filled-system thermometers, and base-metal thermocouples, in which the highest degree of accuracy is not required. Optical pyrometers as secondary standards are compared with primary-standard optical pyrometers, and they are then used for calibration of r ular test pyrometers. 

The filled melting point tube is now attached to the lower end of a thermometer in such a way that the substance is at the level of the middle... 

Two convenient forms of bath are shown ui Fig. 11,10, 2, a and 6. The former consists of a long-necked, round-bottomed flask (a longnecked Kjeldahl flask of 100 ml. capacity is quite satisfactory) supported by means of a clamp near the upper part of the neck. The thermometer is fltted through a cork, a section of the cork being cut away (see inset) so that the thermometer scale is visible and also to allow free expansion of the air in the apparatus. The bulb is about three-quarters filled with... 

Fig. II, 16, 1 illustrates a set-up for simple fractionation a Hempel column is shown, but it may be substituted by a modified Hempel, a Vigreux or an all-glass Dufiton column. The Hempel column may be filled with glass rings, h porcelain Lessing rings, or with porcelain rings. The mixture to be fractionated is placed in a bolt - head flask of convenient size (it should be one third to one half full), a few fragments of porous porcelain added, the column fixed in position, and a water condenserattacfied to the side arm. The distillate is collected in small flasks or in test tubes. The bulb of the thermometer should be just below the level of the side arm.

Equip a I litre three-necked flask with a mechanical stirrer and a thermometer, and immerse the flask in a bath of ice and salt. Place 306 g. (283 ml.) of acetic anhydride, 300 g. (285 ml.) of glacial acetic acid and 25 g. of p-nitrotoluene in the flask, and add slowly, with stirring, 42 5 ml. of concentrated sulphuric acid. When the temperature has fallen to 5°, introduce 50 g. of A.R. chromic anhydride in small portions at such a rate that the temperature does not rise above 10° continue the stirring for 10 minutes after all the chromium trioxide has been added. Pour the contents of the flask into a 3 litre beaker two-thirds filled with crushed ice and almost fill the beaker with cold water. Filter the solid at the pump and wash it with cold water until the washings are colourless. Suspend the product in 250 ml. of cold 2 per cent, sodium carbonate solution and stir mechanically for 10-15 minutes filter (1), wash with cold water, and finally with 10 ml. of alcohol. Dry in a vacuum desiccator the yield of crude p-nitrobenzal diacetate is 26 g. (2),... 

The density determination may be carried out at the temperature of the laboratory. The liquid should stand for at least one hour and a thermometer placed either in the liquid (if practicable) or in its immediate vicinity. It is usually better to conduct the measurement at a temperature of 20° or 25° throughout this volume a standard temperature of 20° will be adopted. To determine the density of a liquid at 20°, a clean, corked test-tube containing about 5 ml. of toe liquid is immersed for about three-quarters of its length in a water thermostat at 20° for about 2 hours. An empty test-tube and a shallow beaker (e.g., a Baco beaker) are also supported in the thermostat so that only the rims protrude above the surface of the water the pycnometer is supported by its capillary arms on the rim of the test-tube, and the small crucible is placed in the beaker, which is covered with a clock glass. When the liquid has acquired the temperature of the thermostat, the small crucible is removed, charged with the liquid, the pycnometer rapidly filled and adjusted to the mark. With practice, the whole operation can be completed in about half a minute. The error introduced if the temperature of the laboratory differs by as much as 10° from that of the thermostat does not exceed 1 mg. if the temperature of the laboratory is adjusted so that it does not differ by more than 1-2° from 20°, the error is negligible. The weight of the empty pycnometer and also filled with distilled (preferably conductivity) water at 20° should also be determined. The density of the liquid can then be computed. 

After the addition of the propyne the thermometer-gas outlet combination was replaced with a "cold finger" filled with dry-ice and acetone. The top of this reflux condenser was connected via a plastic tube with a cold trap (-75°C) containing 50 ml of dry THF. The cooling bath was removed and the conversion of propyne started... 

Appavatus-. For the first reaction a 500-ml round-bottomed flask with a thermometer and a gas outlet, connected with a tube filled with calcium chloride for the second reaction a 100-ml round-bottomed flask with a thermometer. 

Apparatus-. 500-ml round-bottomed flask with a combination of thermometer and vent, connected to a drying tube filled with lumps of anhydrous calcium chloride. 

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