Search results
Results from the WOW.Com Content Network
In its standard state arsine is a colorless, denser-than-air gas that is slightly soluble in water (20% at 20 °C) [1] and in many organic solvents as well. [citation needed] Arsine itself is odorless, [5] but it oxidizes in air and this creates a slight garlic or fish-like scent when the compound is present above 0.5 ppm. [6]
Arsenic has been known since ancient times to be poisonous to humans. [13] However, a few species of bacteria are able to use arsenic compounds as respiratory metabolites. Trace quantities of arsenic have been proposed to be an essential dietary element in rats, hamsters, goats, and chickens. Research has not been conducted to determine whether ...
Marsh test. The Marsh test is a highly sensitive method in the detection of arsenic, especially useful in the field of forensic toxicology when arsenic was used as a poison. It was developed by the chemist James Marsh and first published in 1836. [1] The method continued to be used, with improvements, in forensic toxicology until the 1970s. [2]
Carl Wilhelm Scheele. Carl Wilhelm Scheele (German: [ˈʃeːlə], Swedish: [ˈɧêːlɛ]; 9 December 1742 – 21 May 1786 [2]) was a German Swedish [3] pharmaceutical chemist. Scheele discovered oxygen (although Joseph Priestley published his findings first), and identified molybdenum, tungsten, barium, nitrogen, and chlorine, among others.
It may also be found in the soil and air. [5] Recommended levels in water are less than 10–50 μg/L (10–50 parts per billion). [1] Other routes of exposure include toxic waste sites and pseudo-medicine. [1] [3] Most cases of poisoning are accidental. [1] Arsenic acts by changing the functioning of around 200 enzymes. [1]
In humans, arsenic of these valences is readily absorbed by the gastrointestinal tract, which accounts for its high toxicity. Pentavalent arsenic tends to be reduced to trivalent arsenic and trivalent arsenic tends to proceed via oxidative methylation in which the trivalent arsenic is made into mono, di and trimethylated products by ...
[2] [3] Some of the earliest known traces of controlled fire were found at the Daughters of Jacob Bridge, Israel, and dated to ~790,000 years ago. [4] [5] At the site, archaeologists also found the oldest likely evidence of controlled use of fire to cook food ~780,000 years ago. [6] [7] However, some studies suggest cooking started ~1.8 million ...
e. The arsenic (As) cycle is the biogeochemical cycle of natural and anthropogenic exchanges of arsenic terms through the atmosphere, lithosphere, pedosphere, hydrosphere, and biosphere. Although arsenic is naturally abundant in the Earth's crust, long-term exposure and high concentrations of arsenic can be detrimental to human health. [1][2]