Thermometer partial immersion

Thermometers— Partial immersion thermometers as listed in Table 1, conforming to Specification E 1. Both bore corrections and dther ice or steam standardization corrections are recommended. 

The stem correction may be avoided by employing a thermometer with a short scale (sometimes termed an Anschutz thermometer) and of such size that the entire column of mercury is immersed in the vapour or in the liquid. In practice, it is generally more convenient to use thermometers which have been graduated for partial immersion for a short and con-... 

Partial enzyme inhibition, 10 318, 320 Partial glycerides, 10 802-804 Partial immersion thermometers, 24 464 -465... 

The BurStds thermometer and other thermometers calibrated for total immersion should be used only for detn of sp of TNT by the Specification Method, while for routine tests the thermometers calibrated to partial immersion should be used. F or calibration of such thermometers proceed as follows a)Make a mark ca 5cm from the bottom of the bulb and at least lcm above the upper (small) mercury bulb on each special thermometer graduated in 0.1 or 0.05° b)Tie thermometers together in pairs (with a strip of rubber tubing) and be ready for calibration by custard cup method c)Wash and dry a Pyrex custard cup ca 2.5 in diam and ca 2.5 deep. In order to hold the cup and thermometers in place, use a wooden stand as shown in Fig... 

A 400-ml. three-necked flask equipped with a mechanical stirrer, a gas dispersion tube, and a thermometer is charged with 216 g. (4 moles) of 2-butyne, 14 ml. of boron trifluoride etherate, and 1 ml. of water The mixture is stirred vigorously while the flask is partially immersed in a dry ice-acetone bath to maintain an internal temperature of —20°. Chlorine (195 g., 2.75 moles) is then added (Note 1) gradually over a period of 17-20 hours. 

Total immersion type low temperature pentane thermometers (Kessler) were used to measure the temperature in the partial immersion mode. The readings are usually 7-8°C higher compared to the actual temperature under our reaction conditions. The temperatures reported here are all corrected by subtracting 7°C from the thermometer readings. The checkers used a Delta MC-20R digital thermometer (Sato Keiryoki Co., Japan). Temperature control is very important to obtain a satisfactory yield. 

Each chamber will contain a partial immersion thermometer in a container of fluid. 

Partial-immersion thermometers. Thermometers that require only the... 

There are many specialized thermometers available. Some are used to obtain maximum and minimum temperatures, while others are used for specific tests. The ASTM has defined a series of special partial-immersion thermometers for specific tests. These thermometers are identified as ASTM thermometers and are marked with a number followed by a C (for centigrade) or an F (for Fahrenheit). The number is strictly an identifying number with no relation to the temper-... 

Partial-immersion thermometers have a greater tolerance (and therefore less precision) than total immersion thermometers. Interestingly enough, when a total immersion thermometer is only partially immersed and no stem correction is made, the accuracy is likely to be less than a partial-immersion thermometer. 

Because partial-immersion thermometers are designed for a specific test, uniformity of procedure is more important than overall accuracy. 

The thermometer should be inserted so that the thermometer is immersed to the 0.0°C level (if calibrating a complete-immersion thermometer) or inserted to the immersion line (if calibrating a partial-immersion thermometer). The thermometer is likely to require support to maintain its proper position. Let the entire apparatus sit for 15 to 30 minutes, to reach equilibrium. Periodically add more ice, as needed, and remove any excess water with the siphon. If the ice is kept clean and... 

The thermometers are of the mercury in glass type, and the column above the liquid is filled with nitrogen. They may be standardized for total immersion or for partial immersion and should be used as near as practicable under the same condition of immersion. 

Total immersion means standardization with the thermometer immersed to the top of the mercury column, with the remainder of the stem and the upper expansion chamber exposed to the ambient temperature. Partial immersion means standardization with the thermometer immersed to the indicated immersion line etched on the front of the thermometer, with the remainder of the stem exposed to the ambient temperature. If used under any other condition of immersion, an emergent-stem correction is necessary to obtain correct temperature readings. 

Thermometer Use a partial immersion thermometer with a suitable range. 

Cuvettes Use 10-mm light-path fused quartz. Thermometer Use a partial immersion thermometer with a suitable range, graduated in 1/10°. 

For most purposes a partial-immersion thermometer need not be stem corrected because of a few degrees variation in room temperature or a few degrees error in the immersion level. On the other hand, it is usually worthwhile to apply stem corrections to readings of a total-immersion thermometer when it is used in partial immersion, particularly when reading temperatmes well removed from room temperatures. 

Thermometers niciku suiii llial you use. a partial-immersion ihnrmometor not a total-inimersion thermometer. The type is written on the back of the theimonuiler. i. 

The boiling point is one of the most important physical constants of a liquid. It is also easily determined with sufficient accuracy for most purposes if a reasonable quantity of a pure substance is available, for then it is only necessar to carefully distill the sample, noting both the vapor temperature and the barometric pressure. A particularly convenient apparatus for distillation of small quantities is shown in Fig. 1-10. The shape of the flask here is a desirable one because it confines the liquid to a smaller area than does a round-bottom flask. Thermometers with standard taper joints (1-in. immersion) are very convenient and reduce the possibility of contamination, and in vacuum distillation, of leakage. They are also calibrated for partial immersion, thus making emergent stem corrections (page 83) unnecessary. They... 

Ordinary laboratory thermometers are designed for either total immersion or partial immersion. One can readily see that there would be a difference between these two conditions, since with total immersion the entire mercury column would be heated, and consequently the mercury would have a larger volume than obtained with partial immersion. The amount which must be added to a total-immersion thermometer when it is only partially immersed is given by... 

For most purposes, it is convenient to use partial-immersion thermometers, because the corrections required at any temperature will usually be smaller. However, regardless of which type is used, it should be calibrated against some thermometers for which the calibrations are known. The common practice of calibrating thermometers by using the melting points of known substances will often lead to considerable errors if the capillary method is used. 

Thermometer correction. The temperature which is read on the thermometric scale must be corrected because there are several errors in such determinations. One source of error arises from the construction and calibration of the thermometer. The bore of the capillary may not have the same diameter throughout further, the scale graduation and the calibration of low-priced thermometers are not very accurate. A second source of error is the method used in the common melting point apparatus. The common thermometer has been calibrated while totally immersed in a bath. In the melting-point apparatus described, only a part of the stem is immersed. The column of mercury above the oil bath has a lower temperature than that at which the thermometer was calibrated. Therefore either a thermometer calibrated by partial immersion should be used or a correction must be made for the unequal heating of the mercury in the stem of the thermometer. Although thermometers calibrated by partial immersion are available, the latter practice is the more common. 

If it is necessary to use a thermometer for partial immersion, that is, with the bulb and only a part of the stem heated, it is advisable to use the continuous-scale type (6) or (c) rather than the standard type (a), especially if the enlargement in the capillary shown between the 0 and 295° marks projects out into the air which is much cooler than the bulb. Large and uncertain errors may be introduced by using a thermometer under these conditions. 

The thermometers are, however, rarely used under this condition, but in nearly all cases are used at partial immersion, the bulb and a short length of the stem being exposed to the temperature to be measured, while the remainder of the stem projects above the bath into the (usually) cooler air of the room. In the following it will be assumed that the thermometer is in a heated bath. In this case, the emergent mercury column is cooler than the bath, consequently the thermometer reads too low. The amount, in degrees, by which it reads too low, may be calculated from the formula,... 

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