Alcohol thermometer

When bulb thermometers are employed where there is a likelihood of a magnetic field, alcohol thermometers shotdd be preferred to mercury thermometers, as the latter ire unreliiiblc under stich conditions. 

The ambient temperature should be measured during the last quarter of the test by at least three thermometers or thermocouples placed equally around the switchgear assembly, at almost the centre level and at about I metre from the body of the enclosure. The ambient temperature to be considered must be the average of these readings and should be within 10-40°C. To ensure that the ambient temperature is unaffected by ntagnetic field, alcohol thermometers must be used and not mercury thermometers. 

All reagents were purchased from Aldrich Chemical Company (except for trimethylacetyl chloride, which the checkers obtained from Acros) and were used without further purification. The checkers used a low temperature alcohol thermometer in place of a Teflon-coated themocouple. The third neck of the flask was left open to the atmosphere. 

Mid-1600 Liquid-in-glass graduated thermometers are widely spread Famous are die alcohol thermometers of die Accademia del Cimento in Florence. Their graduation marks are made of coloured glass bits attached to die stem... 

Because of the inaccuracy of alcohol thermometers it is strongly recommended that one monitor those reactions that are run below -80°C with a resistance thermometer. The submitters used an apparatus purchased from Ebro, D-Ingolstadt. 

The determination of the temperatures of crystallization of the mixtures was carried out in a closed glass apparatus with a manual stirrer. This entered the vessel through a hole of tight bore in the rubber stopper, which was greased with vaseline, so that the accession of atmospheric moisture was reduced to a minimum. Temperatures above 0°C were measured with a mercury thermometer with scale divisions of 0-1°, which was calibrated by the ice-water mixture at 0° and by the Na2S04 0H2O transition point at 32 38°. For temperatures below 0° an alcohol thermometer with 0 2° scale divisions was used. It was calibrated also at 0° with the ice-water mixture. Since the thermometer capillary was at room temperature in the course of the determinations, a correction for its expansion was applied. The low temperatures were obtained by means of dry ice-acetone mixtures. 

A mixture of 493 g. (2.00 moles) of magnesium sulfate hepta-hydrate and 700 ml. of tap water is stirred for 5 minutes and filtered into a 2-1. three-necked flask equipped with a mechanical stirrer and an alcohol thermometer that dips into the solution. The flask is immersed in a cooling bath (Note 1), the stirrer is started, and the solution is cooled to 10°. To the solution is added, in one portion, 143 g. (2.20 moles) of potassium cyanide Caution Toxic), and the stirring is continued for 45 minutes at 8-12° (Note 2). The solution is maintained at this temperature while 102 g. (1.10 moles) of epichlorohydrin (Note 3) is added dropwise with stirring over a period of 1 hour (Note 4). The mixture is allowed to come to room temperature and is stirred for an additional 24 hours at this temperature. 

Alcohol thermometers were found not to read temperatures accurately. A temperature of -78°C designates the lowest temperature to which a large dry ice-acetone bath cools the reaction mixture. The temperature -75°C signifies a 3° rise in temperature. 

A Pt-100 thermometer (Testoterm KG, Lenzklrch, Germany) was used by the submitters. This 1s preferred to a conventional thermometer, because it is more accurate and more convenient to read. Careful temperature control is essential for the present procedure. Unless stated otherwise, all temperatures given are those of the reaction mixture. The checkers found that a +30 to -100°C alcohol thermometer is satisfactory. 

Hydrogen peroxide and peroxycarboxylic acids (RCO3H) are normally relatively stable, but as mentioned above they can be rendered unstable by a wide variety of contaminants, particularly at excessively high temperatures. Cleanliness, good housekeeping and proper storage are therefore essential. The major contaminants that cause decomposition are combustible organic materials (e.g. cotton, wool, paper) or metals, particularly transition metals and their salts (Table 1.7).50 Alcohol thermometers or stainless steel thermocouples... 

Use alcohol thermometers, stainless steel thermocouples and stainless steel ball hydrometers. 

Gas thermometers tend to be awkward in use. The general practice, therefore, is to employ, where possible, other thermometers that exhibit a near-linear variation of some other property x, with the empirical temperature r. A common device for this purpose is the mercury or alcohol thermometer which expands in volume as r rises. For many liquids the quantity a (1/V) (3V/dT)P remains approximately constant. Thus (3V/dT) >... 

Gabriel Fahrenheit invents an alcohol thermometer (mercury thermometer developed in 1714)... 

If the temperature of the liquid or solution being cooled is critical, do not assume that the temperature of the liquid or solution is the same as that of the cooling bath place a thermometer in the flask and remember that for temperatures lower than —5 C you should use an alcohol thermometer (red thread) or a thermocouple-type thermometer (after checking that the probe will not react with the contents of the flask). 

Unfortunately, Florentine thermometers, or any thermometers of the time, were not very accurate no two thermometers gave the same temperature, since there was no universal acceptance of liquid type or agreement on what to use for a scale. Makers of Florentine thermometers marked the lowest scale as the coldest day in Florence that year and the highest scale for the hottest day. Since temperature fluctuations naturally occur over the years, no two thermometers gave the same temperature. For several years Fahrenheit experimented with this problem, finally devising an accurate alcohol thermometer in 1709 and the first mercury or quicksilver thermometer in 1714. 

His thermometer of 1731 used a mixture of alcohol (wine) and water instead of mercury, perhaps creating the first alcohol thermometer, and it was calibrated... 

Equation (1-4) is used for the mercury or alcohol thermometer, as well as for gas thermometers containing or He. It is found experimentally that the niimerical value of the temperature, except the values at the ice and steam points which are fixed, depends upon the particular system and thermometric property employed. Because there is less variation among gas thermometers, a gas is usually chosen as the standard thermometric substance. 

KATA THERMOMETER - Large-bulb alcohol thermometer used to measure air speed or atmospheric conditions by means of cooling effect. 

Despite the advantages of Hg, alcohol thermometers are replacing mercury as the liquid of choice principally driven by safety considerations. Mercury is toxic. Moreover, when the thermometer breaks, mercury beads into small spheres making it difficult to clean, which increases both its environmental and health hazard. Disadvantages of solvents include their lower thermal conductivity, which are as much as 50 times lower than mercury and their high vapor pressure resulting in a lower level in the capillary and thus in the possible underestimation of the true temperature. 

Alcohol thermometers can measure temperatures in the tai of — 100°F to200°F. Determine the temperature at vdbich an alcohol thermometer with a Fahrenhdu scale will read the same number as a thermometer with a Celsius scale. 

---