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See also:CAISSON DISEASE . In See also:- ORDER
- ORDER (through Fr. ordre, for earlier ordene, from Lat. ordo, ordinis, rank, service, arrangement; the ultimate source is generally taken to be the root seen in Lat. oriri, rise, arise, begin; cf. " origin ")
- ORDER, HOLY
order to exclude the See also:water, the See also:air pressure within a caisson used for subaqueous See also:works must be kept in excess of the pressure due to the superincumbent water; that is, it must be increased by one See also:atmosphere, or 15 lb per sq. in. for every 331 ft. that the caisson is submerged below the See also:surface. Hence at a See also:depth of too ft. a worker in a caisson, or a See also:diver in a diving-See also:dress, must be subjected to a pressure of four atmospheres or 6o lb per sq. in. Exposure to such pressures is See also:apt to be followed by disagreeable and even dangerous physiological effects, which are commonly referred to as caisson disease or compressed air illness. The symptoms are of a very varied See also:character, including pains in the muscles and See also:joints (the " bends "), deafness, embarrassed breathing, vomiting, See also:paralysis (" See also:divers' palsy "), fainting and sometimes even sudden See also:death. At the St See also:- LOUIS
- LOUIS (804–876)
- LOUIS (893–911)
- LOUIS, JOSEPH DOMINIQUE, BARON (1755-1837)
- LOUIS, or LEWIS (from the Frankish Chlodowich, Chlodwig, Latinized as Chlodowius, Lodhuwicus, Lodhuvicus, whence-in the Strassburg oath of 842-0. Fr. Lodhuwigs, then Chlovis, Loys and later Louis, whence Span. Luiz and—through the Angevin kings—Hungarian
Louis See also:bridge, where a pressure was employed equal to 44 atmospheres, out of 600 workmen, ttq were affected and 14 died. At one See also:- TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
- TIME, MEASUREMENT OF
- TIME, STANDARD
time the symptoms were attributed to congestion produced by the See also:mechanical effects of the pressure on the See also:internal See also:organs of the See also:body, but this explanation is seen to be untenable when it is remembered that the pressure is immediately transmitted by the fluids of the body equally to all parts. They do not appear during the time that the pressure is being raised nor so See also:long as it is continued, but only after it has been removed; and the view now generally accepted is that they are due to the rapid effervescence of the gases which are absorbed in the body-fluids during exposure to pressure. Experiment has proved that in animals exposed to compressed air See also:nitrogen is dissolved in the fluids in accordance with See also:Dalton's See also:law, to the extent of roughly r % for each atmosphere of pressure, and also that when the pressure is suddenly relieved the See also:gas is liberated in bubbles within the body. It is these bubbles that do the See also:mischief. Set See also:free in the See also:spinal See also:cord, for instance, they may give rise to partial paralysis, in the See also:labyrinth of the See also:ear to auditory vertigo, or in the See also:heart to stoppage of the circulation; on the other See also:hand, they may be liberated in positions where they do no harm. But if the pressure is relieved gradually they are not formed, because the gas comes out of See also:solution slowly and is got rid of by the heart and lungs. See also:Paul See also:Bert exposed 24 See also:dogs to pressure of 7-91 atmospheres and " decompressed " them rapidly in 1-4 minutes. The result was that 21 died, while only one showed no symptoms. In one of his cases, in which the apparatus burst while at a pressure of 91 atmospheres, death was instantaneous and the body was enormously distended, with the right heart full of gas.
But he also found that dogs exposed, for moderate periods, to similar pressures suffered no See also:ill effects provided that the pressure was relieved gradually, in x-11 See also:hours; and his results have been confirmed by subsequent investigators. To prevent caisson disease, therefore, the decompression should be slow; Leonard See also:- HILL
- HILL (0. Eng. hyll; cf. Low Ger. hull, Mid. Dutch hul, allied to Lat. celsus, high, collis, hill, &c.)
- HILL, A
- HILL, AARON (1685-175o)
- HILL, AMBROSE POWELL
- HILL, DANIEL HARVEY (1821-1889)
- HILL, DAVID BENNETT (1843–1910)
- HILL, GEORGE BIRKBECK NORMAN (1835-1903)
- HILL, JAMES J
- HILL, JOHN (c. 1716-1775)
- HILL, MATTHEW DAVENPORT (1792-1872)
- HILL, OCTAVIA (1838– )
- HILL, ROWLAND (1744–1833)
- HILL, SIR ROWLAND (1795-1879)
Hill suggests it should be at a See also:rate of not less than 20 minutes for each atmosphere of pressure. See also:Good See also:ventilation of the caisson is also of See also:great importance (though experiment does not entirely confirm the view that the presence of carbonic See also:acid to an amount exceeding 1 or 14 parts per thousand exercises a specific See also:influence on the See also:production of compressed air illness), and long shifts should be avoided, because by fatigue the circulatory and See also:respiratory organs are rendered less able to eliminate the absorbed gas. Another See also:reason against long shifts, especially at high pressures, is that a high partial pressure of See also:oxygen acts as a See also:general protoplasmic See also:poison. This circumstance also sets a limit to the pressures that can possibly be used in caissons and therefore to the depths at which they can be worked, though there is reason to think that the maximum pressure (44 atmospheres) so far used in caisson See also:work might be considerably exceeded with safety, provided that proper precautions were observed in regard to slow decompression, the physique of the workmen, and the hours of labour. As to the remedy for the symptoms after they have appeared, satisfactory results have been obtained by replacing the sufferers in a compressed air chamber (" recompression "), when the gas is again dissolved by the body fluids, and then slowly " decompressing " them.
See Paul Bert, La Pression barometrique (1878) ; and Leonard Hill, See also:Recent Advances in See also:Physiology and Biochemistry (1906), (both these works contain See also:bibliographies); also a lecture by Leonard Hill delivered at the Royal Institution of Great See also:Britain on the 25th of May 1906; " Diving and Caisson Disease," a See also:summary of recent investigations, by Surgeon See also:Howard Mummery, See also:British Medical See also:Journal, See also:June 27th, 1908; Diseases of Occupation, by T. See also:Oliver (1908); Diseases of Workmen, by T. Luson and R. See also:Hyde (1908).
End of Article: CAISSON DISEASE
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