Save Save Save Save. Even the famous Leonardo Da Vinci fell for it and drew a heart with only two chambers. For the first time it is acknowledged that the heart has four chambers and not two. Save Save. The first study on blood circulation was published in by William Harvey —an English physician. He came to the conclusion that the heart acts as a pump. The physician then concluded that blood must be going though a cycle.
Many scientists were involved. Among them, major triumphs were achieved by William Harvey during the early s who announced that there is a finite amount of blood that circulated the body in one direction only. In the mids, Reverend Stephen Hales reported the first invasive measurement in horses and smaller animals. One of the early forms was the Geissler tube. When subjected to a large voltage difference, mercury vapour emits short-wave ultraviolet light.
This can be used as is, as in the case of UV and germicidal lamps; or the inside of the tube can be coated with a mixture of phosphors, which are excited by the UV light to emit visible light eg: compact fluorescent lights. Mercury has had several medicinal uses, of varying effectiveness. One prominent use was in forming amalgams with gold, and used in dentistry to fill cavities, but its use has been severely limited, if not outright banned in recent years.
Other uses included as an ingredient in some laxatives, diaper-rash ointments, topical antiseptics eg: Merbromin, sold as Mercurochrome and Merbromine , and as biological tissue dye. Other less useful, if not outright harmful applications ranged from immortality pills which are credited in the death of the first Chinese emperor Qin Shi Huang , whose tomb, according to legend, has rivers of mercury , as a fertility treatment, and for treating skin ailments.
Mercury was in famously used treat syphilis eg: mercury I chloride aka calomel , and blue mass which was also used in many other conditions too , from the 16 th century, up until the early 20 th when antisyphilitics became available. Calomel was also used in teething powders until the mid 's.
This resulted in many cases of mercury poisoning. Symptoms included itching, rashes, and swelling, and became known as pink disease, or acrodynia. The toxic nature of mercury has been known since antiquity, with slaves and convicts being sent to the Roman cinnabar mines known to have greatly reduced life expectancies.
The German chemist Alfred Stock performed much research on mercury and mercury poisoning around the 's and 30's, and tried to stop the use of mercury and its derivatives. Through his work, Stock was exposed to low levels of mercury vapour over a long time, and endured chronic mild poisoning. He described symptoms of poor memory, lethargy, and depression.
Perhaps the best know instance of mercury poisoning occurred in Minamata city, Kumamoto prefecture, Japan, and discovered around Methylmercury contaminated wastewater was dumped into the sea from to This bioaccumulated in the seafood, some of which was eventually caught and eaten, causing mercury poisoning, and became known as "dancing cat fever", or Minamata disease , officially claiming 1, lives. Symptoms included rashes, ataxia, numbness, general muscle weakness, peripheral blindness, paralysis, insanity, and could lead to death.
Some mercury can be naturally expelled after a time, as in the case of mercury diuretics and laxatives. There are some compounds that can be used in chelation therapies.
As you can see, several of these are mercaptan-based compounds. Mercaptans are organosulphur compounds a with carbon-bonded sulphydryl -SH group, and are also known as thiols. They are also used as an odorant to make natural gas noticeable the rotten egg smell. Unfortunately, the neurological symptoms of severe poisoning seem to be irreversible.
Mercury has been used for several thousands of years for many reasons, and its toxic nature has been known since at least classical times. Thanks to scientific advances, mercury has largely been replaced by safer compounds in many of these uses, but it still retains some niche uses eg: in high accuracy thermometers and barometers. A drawing of Torricelli's early barometer. A stamp from the USSR.
Outstanding Italian physicist and mathematician. Evangelista Torricelli " Source: Wikipedia. Low pressure. Source: Explain That Stuff. High pressure. A Bourdon tube meter. Source: Wikipedia. William Harvey, William Harvey " Source: Wikipedia. Stephen Hales mezzotint from the Wellcome Library. Karl von Vierordt. Vierordt's sphygmograph. Once the correlation between heart rate and pulse was discovered, it was possible to determine blood volume and blood pressure.
In Reverend Stephen Hales recorded the first blood pressure measurement on a horse. He did this by inserting a long glass tube upright into an artery, observing the increase in pressure as blood was forced up the tube. It consisted of a rubber bulb that was filled with water to restrict blood flow in the artery. The bulb was then connected to a mercury column, which would translate the pressure required to completely obscure the pulse into millimeters of mercury. In , the device was further improved by Scipione Riva-Rocci.
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