Torricelli

In the late fifteenth century AD mercury was successfully used as a treatment for syphilis. In the late sixteenth century the development of the Patio process for the recovery of silver by amalgamation (see Silverand silveralloys) greatiy increased the consumption of mercury. Usage of mercury increased in 1643 when Torricelli invented the barometer, and again in 1720 when Fahrenheit invented the mercury thermometer. Other scientific and medical appHcations foUowed. Industrial usage after 1900, particularly in electrical appHcations, expanded rapidly, offsetting the sharp decline in its use in amalgamation. 

Mechanism of Water Flow from Tank— Torricellis Law, A Constitutive Relationship... 

Ananalysisofthisdatashowsthatthe flowrateoutofthevesselisdirectlyproportionaltothe orificearea.Fromexperimentslikethese,Torricelli finallydeducedthatthe flowratelooked... 

AlthoughTorricellididnotknowthis,hisworkhelpedtopointNewtonintherightdirection. Therefore,Torricelli sLawistheconstitutiverelationshipthatweseektocompleteoumiodel. Wereturntothatendeavornow. 

In the second case the outlet flow rate is given by Torricelli s Law, that is, qsoln=... 

Liquid discharge from the work of Bernoulli and Torricelli is given by... 

The torr i.s a unit of pre.s.snre named for Torricelli, inventor of die barometer. 1 torr corre-.spond.s to 1 mm Hg (l/760dr of an atmo.sphere). 

A mercury barometer. This is the type of barometer first constructed by Torricelli. The pressure of the atmosphere pushes the mercury in the dish to rise into the glass tube. The height of the column of mercury is a measure of the atmospheric pressure. 

A device commonly used to measure atmospheric pressure is the mercury barometer (Figure 5.1), first constructed by Evangelista Torricelli in the seventeenth century. This consists of a closed gas tube filled with mercury inverted over a pool of mercury. The pressure exerted by the mercury column exactly equals that of the atmosphere. Hence the height of the column is a measure of the atmospheric pressure. At or near sea level, it typically varies from 740 to 760 mm, depending on weather conditions. 

Torricelli, Evangelista, 104 Trans isomer A geometric isomer in which two identical groups are as far apart as possible, e.g., a b, 414,598... 

The pressure of the atmosphere can be measured with a barometer, an instrument invented in the seventeenth century by Evangelista Torricelli, a student of Galileo. Torricelli (whose name coincidentally means little tower in Italian) formed a little tower of liquid mercury. He sealed a long glass tube at one end, filled it with mercury, and inverted it into a beaker (Fig. 4.4). The column of mercury fell until the pressure that it exerted at its base matched the pressure exerted by the atmosphere. To interpret measurements with a barometer, we need to find how the height of the column of mercury depends on the atmospheric pressure. 

Cubeddu R., Pifferi A., Taroni P., Torricelli A., Valentini G., Compact tissue oximeter based on dual-wavelength multichannel time-resolved reflectance, Appl. Opt. 1999 38 3670. 

Cubeddu R,Pifferi A, TaroniP, Torricelli A, ValentiniG,Comelli D, D AndreaC,Angelini V, Canti G (2000) Photochem Photobiol 72 690... 

Although mercury is known from early times and was used hy alchemists, its first modern scientific applications date hack to 1643 when Torricelli used it in the barometer to measure pressure and about eight decades later Fahrenheit used it in the thermometer to measure temperature. Before this, mercury s use was confined to decorative work, gold extraction and medicines. The element was named after the planet mercury and its symbol Hg is taken from the Latin word hydrargyrum, which means hquid silver. 

If by His mandate Torricelli Poised air s vast sea in slender tube,... 

Si SI hizo A Torricelli que pesase En tubo estrecho el mar de la atmosfera ... 

He inverted the tube in a pool of mercury. Torricelli noticed that the mercury in the tube fell, creating a vacuum at the top of the tube. The final height of the mercury in the tube was roughly 28 inches. Because mercury has 13.5 times the density of water, Torricelli proposed that water should rise about 13.5 X 28 inches or about 32 feet. Torricelli reasoned that atmospheric pressure placed a limit on how high a liquid could raise in the tube. His inverted mercury-filled tube was the first barometer (Figure 9.1). 

Thompson, William (Lord Kelvin), 104,105 Thomson, Joseph John, 36, 37, 38, 73, 176 Topham, Charles, 297 Torricelli, Evangelista, 99, 100 Tyndall, John, 137... 

There are two types of U-tube manometer the open-ended manometer is obviously inconvenient for low pressure measurements if an organic liquid of low vapour pressure is used instead of mercury. The small U-tube with one sealed end is the most common and convenient form. The sealed end is closed whilst the tube is under a good vacuum (p < 10 Torr) and, provided that precautions are taken to preserve the vacuum, the pressure in this reference space (the Torricelli vacuum) can be neglected when calculating the measured pressure. 

The height of the mercury column in a barometer on a typical day at sea level is about 760 mm, which we have seen corresponds to 101 kPa. This pressure could be reported as 760 mmHg. The unit 1 mmHg has been largely replaced by the unit 1 Torr (named for Torricelli), with 1 Torr = 1 mmHg so normal atmospheric pressure is about 760 Torr. Atmospheric pressure varies with altitude and weather. The pressure of the atmosphere at the cruising height of a commercial jetliner (10 km) is only about 200 Torr, so airplane cabins must be pressurized. 

The millimeter of mercury, also called a ton after the seventeenth-century Italian scientist Evangelista Torricelli (1608-1647), is based on atmospheric pressure... 

Air pressure is caused by its weight. Measuring air pressure is like weighing a 960 km high column of air in a balance Torricelli was the first to device a simple method to measure the air pressure. 

He took a long glass tube open at one end and filled it fully with mercury. Closing the open end of the glass tube with his thumb, he inverted it into a glass dish containing mercury. When his thumb was removed, the mercury dropped to 76 cm level. The length of the tube or its cross section did not matter. The vacuum above the mercury column is still called Torricelli s vacuum . Modem barometers are based on this principle. 

Valentini G, D Andrea C, Comelli D, Pifferi A, Taroni P, Torricelli A, Cubeddu R, Battaglia C, Consolandi C, Salani G (2000) Opt Lett 25 1648-1650... 

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