Hi,

#6675. Name the visual aid that allows the user to measure more precisely than could be done unaided when reading a uniformly divided straight or circular measurement scale. It is a scale that indicates where the measurement lies in between two of the graduations on the main scale.

6676.  Name the Dutch spectacle-maker from Middelburg associated with the invention of the first optical telescope (1585 – pre-1632). He is sometimes also credited for inventing the first truly compound microscope. However, the origin of the microscope, just like the origin of the telescope, is a matter of debate.

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The solution #6212 is perfect! Keep it up, math9maniac!

#6213. A solid metallic sphere of diameter 28 cm is melted and recast into a number of smaller cones, each of diameter

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The Answer #1117 is correct. Excellent, David!

#1118. Name the uncommon inflammatory disease that causes muscle weakness affecting both sides of your body. Having this condition can make it difficult to climb stairs, rise from a seated position, lift objects or reach overhead. It most commonly affects adults in their 30s, 40s or 50s. It's more common in blacks than in whites, and women are affected more often than men. Signs and symptoms usually develop gradually, over weeks or months.

207. William Herschel

Scouring the heavens with his sister, Caroline, Sir William Herschel discovered the planet Uranus and several moons around other gas giants. In the course of his studies of the night sky, he also compiled a catalog of 2,500 celestial objects that is still in use today. But it wasn't until his mid-30s that he began to turn his eyes to the expanse above; he started his professional life as a musician.

A musical beginning

Born in Germany as Friedrich Wilhelm Herschel, the astronomer was the son of Anna Ilse Moritzen and Issak Herschel. His father was a military musician, and young William played in the same band in his early years. In 1759, Herschel left Germany for England, where he taught music before becoming an organist.

In 1772, William's sister, Caroline, moved to England to live with her brother and train as a singer. During this time, Herschel's interest in astronomy grew significantly. He rented a small telescope, and his desire to own a larger instrument led him to the process of grinding and polishing his own mirrors.

Caroline never married, but served as his assistant until Herschel's death. She was the first woman to discover a comet, ultimately finding eight. She also discovered several deep-sky objects and was the first woman to be given a paid scientific position and to receive an honorary membership into the Royal Society.

In 1788, at the age of 50, Herschel married the widow Mary Pitt. Their son, John, was born in 1792, and followed in his father's astronomical footsteps.

Searching the skies

On March 13, 1781, Herschel noticed a small object that, over the course of several nights, was slowly moving across the sky. At first he thought he had found a comet, but further observation revealed that the object was a planet. Herschel lobbied to name the new body 'Georgium Sidus', after King George III, but it was eventually named Uranus after the Greek god of the sky. As a result of his discovery, the monarch knighted Herschel and appointed him to the position of court astronomer. The attached pension allowed him to conclude his musical career and focus his full attention on the skies.

When Herschel was subsequently elected a member of the prestigious Royal Society, he received a copy of Charles Messier's "Catalog of Nebulae and Star Clusters," a list of diverse nebulae in the night sky. The catalog piqued his interest, and he began to examine the fuzzy objects.

On Oct. 23, 1783, he began a sky survey of his own, standing on a ladder while peering through his telescope and describing the objects he saw to his sister, Caroline. By pointing the stationary telescope at a single strip of the sky, he was able to observe east-west bands over the course of the night. The next night, he would adjust his telescope to a higher or lower point and observe another parallel strip. Eventually, he examined the entire swatch of sky that could be seen over Great Britain.

Over 20 years, he observed 2,500 new nebulae and star clusters and recorded them in "The General Catalogue of Nebulae." The catalog was eventually enlarged and renamed the "New General Catalogue," and many non-stellar objects are identified by their NGC numbers. Of the 7,840 nebulae and clusters in the catalog today, 4,630 were discovered by Herschel and his son.

In 1789, Herschel finished construction on 40-foot-long (12 meters) telescope, the largest of the day. But the unwieldy instrument came with a number of problems, and Herschel tended to use the smaller, 20-foot (6-meter) telescope.

Herschel discovered several moons around the gas giants. In 1787, he discovered two moons around Uranus: Titania and Oberon. In 1789, using his larger telescope, he found Saturn's sixth and seventh moons, Enceladus and Mimas. [Meet Mimas: Saturn's Death Star Moon]

In 1800, Herschel performed a simple experiment determining the temperature of the different colors of sunlight passed through a prism. He noticed the region just beyond the red color was even higher than light in the visible spectrum, and used his measurements to deduce the presence of what is now known to be infrared radiation. The European Space Agency's infrared space observatory was subsequently named for him.

Herschel proposed the name "asteroids" for the large bodies discovered in 1801. He was elected vice president of the newly formed Royal Astronomical Society in 1820 and president the following year. His last published paper cataloged 145 double stars.

Herschel died in England on Aug. 25, 1822, at the age of 84. Craters on the moon, Mars, and Mimas are named for the astronomer. The asteroid 2000 Herschel bears his name, and the symbol for the planet Uranus features the capital letter H in his honor.

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#6673. Name  the only planet whose name is derived directly from a figure of Greek mythology.

#6674. Name the Scottish physician, chemist and botanist (3 November 1749 - 15 December 1819) who is most famous for the isolation of nitrogen in 1772.

13) The Element Osmium

Atomic Number: 76
Atomic Weight: 190.23
Melting Point: 3306 K (3033°C or 5491°F)
Boiling Point: 5285 K (5012°C or 9054°F)
Density: 22.57 grams per cubic centimeter or 22,570 kilograms per meter cube, The heaviest metal
Phase at Room Temperature: Solid
Element Classification: Metal
Period Number: 6    Group Number: 8    Group Name: none

What's in a name? From the Greek word for a smell, osme.

Say what? Osmium is pronounced as OZ-mee-em.

History and Uses:

Osmium and iridium were discovered at the same time by the British chemist Smithson Tennant in 1803. Osmium and iridium were identified in the black residue remaining after dissolving platinum ore with aqua regia, a mixture of 25% nitric acid (HNO3) and 75% hydrochloric acid (HCl). Today, osmium is primarily recovered during the processing of platinum and nickel ores.

Metallic osmium is hard, brittle and very difficult to make. Powdered osmium is easier to make but emits osmium tetroxide (OsO4) when it is exposed to the air. Unfortunately, osmium tetroxide smells bad and is very poisonous. Because of these problems, osmium is primarily used to make very hard alloys. Osmium alloys can be found in ball point pen tips, fountain pen tips, record player needles, electrical contacts and other devices where frictional wear must be minimized.

Estimated Crustal Abundance:

Estimated Oceanic Abundance: Not Applicable

Number of Stable Isotopes: 5   

Ionization Energy: 8.7 eV

Oxidation States: +4, +3

Electron Shell Configuration:

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#6671. What is 'Réaumur scale'?

#6672. What is 'Heat capacity' or 'thermal capacity'?

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The solution #3797 is correct. Excellent, math9maniac!

#3798. If an integer is added to its square, the sum is 90. Find the integer. (two values)

206. Carl Wilhelm Scheele

Carl Wilhelm Scheele (December 9, 1742 - May 21, 1786), was a German-Swedish pharmaceutical chemist. He was a prolific scientist whose humble circumstances and equipment did not prevent him from making scores of important chemical discoveries. He was the first to discover oxygen and to produce chlorine gas. Yet, much of what he did had to be rediscovered because it was not appreciated by his fellow scientists. Although his name is not as well recognized as many of his contemporaries, his work had a major impact on the development of chemistry.

Biography

Scheele was born in Swedenborn in Stralsund, Western Pomerania, Germany, which was at the time under Swedish rule. He was one of eleven children of a merchant, Joachim Christian Scheele. At age 14, he adopted the vocation of a pharmacist in the establishment of Martin Anders Bauch of Gothenburg. His brother had also worked for Bauer but died three years before Scheele began his apprenticeship. Scheele served for the first six years as a pupil, and three additional years as an assistant. During this period, he availed himself of Bauer's fine library, and by study and practice acquired an advanced knowledge of the chemistry of his day. It is said that he studied at the pharmacy after hours, and while conducting experiments late one evening, he triggered an explosion that shook the house and disturbed its occupants. Scheele was told to look for work elsewhere.

He then was hired as an apothecary's clerk in Kalstom's establishment in Malmö, where he remained for two years. He then served in the establishment of Scharenberg in Stockholm. At this time, he submitted a memoir on the discovery of tartaric acid, but it was rejected by the Swedish Academy of Sciences as he was not well known at the time. This is said to have discouraged Scheele and made him reticent to contact those who would have most appreciated his work. He would not become a member of the academy until he was 33.

International reputation

Scheele's career as a scientist dates to his work in Stockholm. After spending six years there, Scheele transferred to the shop of Look in Uppsala, in 1773. It was during this time that he is said to have met the famous Swedish chemist Torbern Olof Bergman, professor of chemistry at the University of Uppsala. As the story goes, Scheele's employer, who supplied Bergman with his chemicals, brought Bergman to the pharmacy to consult Scheele on a matter that had been mystifying him. Scheele offered a clear explanation, and in other ways demonstrated a depth of understanding of chemical phenomena of all kinds. Besides befriending Scheele, Bergman was instrumental in bringing Scheele's accomplishments to the attention of the scientific community, and in having his work published. Scheele thus began to earn an international reputation, and corresponded with the likes of Henry Cavendish, of Great Britain, and Antoine Lavoisier, of France.

Later years

In 1775, Scheele hoped to purchase a pharmacy so that he could work independently. His first attempts to acquire a business were unsuccessful, but they led to many invitations to do research and teach in a variety of European capitals. Scheele turned these offers down, preferring to remain in a profession he knew well and that provided sufficiently for his expenses. After a year's delay, he was successful in purchasing a shop in Koping from Sara Margaretha Sonneman, who had inherited it from her late husband, Hinrich Pascher Pohls. Scheele found that the establishment was saddled with debt, which he succeeded in paying off by diligent attention to his business affairs over a number of years. During this time, he and Pohls's widow kept house together for the sake of economy. He eventually married her, only a few days before his death. Scheele managed to retire the entire debt of his new business, and was able to build himself a new home and laboratory. One of his sisters came to assist Scheele in managing the pharmacy and household. Thus they were able to live fairly comfortably for Scheele's remaining years.

During the last decade of his life, Scheele was often visited by scientists who tried to probe his fertile mind. Scheele preferred to entertain in his laboratory or at his pharmacy, and traveled little.

He suffered from gout and rheumatism, but continued his scientific work up to the final month of his life. His illness was probably brought on by his constant exposure to the poisonous compounds he worked with. He died on May 21, 1786.

Accomplishments

Discovery of oxygen

Unlike scientists such as Antoine Lavoisier and Isaac Newton, who were more widely recognized, Scheele had a humble position in a small town, and yet he was still able to make many scientific discoveries. He preferred his small dwelling to the grandeur of an extravagant house. Scheele made many discoveries in chemistry before others who are generally given the credit. One of Scheele's most famous discoveries was oxygen produced as a by-product in a number of experiments in which he heated chemicals, during 1771-1772. Scheele, though, was not the one to name or define oxygen; that job would later be bestowed upon Antoine Lavoisier.

Before Scheele made his discovery of oxygen, he studied air. Air was thought to be an element that made up the environment in which chemical reactions took place but did not interfere with the reactions. Scheele's investigation of air enabled him to conclude that air was a mixture of "fire air" and "foul air;" in other words, a mixture of oxygen and nitrogen, the one breathable, the other not. He performed numerous experiments in which he burned substances such as saltpeter (potassium nitrate), manganese dioxide, heavy metal nitrates, silver carbonate and mercuric oxide. However, his findings were not published until 1777 in the treatise, Chemical Treatise on Air and Fire By then, both Joseph Priestley and Antoine Lavoisier had already published their experimental data and conclusions concerning oxygen. In his treatise, Scheele also distinguished heat transfer by thermal radiation from that by convection or conduction.

Scheele's study of "fire air" (oxygen) was sparked by a complaint by Torbern Olof Bergman. Bergman informed Scheele that the saltpeter he purchased from Scheele's employer produced red vapors when it came into contact with acid. Scheele's quick explanation for the vapors led Bergman to suggest that Scheele analyze the properties of manganese dioxide. It was through his studies with manganese dioxide that Scheele developed his concept of "fire air." He ultimately obtained oxygen by heating mercuric oxide, silver carbonate, magnesium nitrate, and saltpeter. Scheele wrote about his findings to Lavoisier who was able to grasp the significance of the results.

Other discoveries

In addition to his joint recognition for the discovery of oxygen, Scheele is argued to have been the first to discover other chemical elements such as barium (1774), manganese (1774), molybdenum (1778), and tungsten (1781), as well as several chemical compounds, including citric acid, glycerol, hydrogen cyanide (also known, in aqueous solution, as prussic acid), hydrogen fluoride, and hydrogen sulfide. In addition, he discovered a process similar to pasteurization, along with a means of mass-producing phosphorus (1769), leading Sweden to become one of the world's leading producers of matches. In 1775, Scheele discovered the mineral pigment copper math, known afterwards as Scheele's Green. The compound was generally replaced by pigments of lower toxicity.

Scheele made one other very important scientific discovery in 1774, arguably more revolutionary than his isolation of oxygen. He identified lime, silica, and iron, in a specimen of pyrolusite given to him by his friend, Johann Gottlieb Gahn, but could not identify an additional component. When he treated the pyrolusite with hydrochloric acid over a warm sand bath, a yellow-green gas with a strong odor was produced. He found that the gas sank to the bottom of an open bottle and was denser than ordinary air. He also noted that the gas was not soluble in water. It turned corks a yellow color and removed all color from wet, blue litmus paper and some flowers. He called this gas with bleaching abilities, "dephlogisticated acid of salt." Eventually, Sir Humphry Davy named the gas chlorine.

Scheele and the phlogiston theory

By the time he was a teenager, Scheele had learned the dominant theory on gases in the 1770s, the phlogiston theory. Phlogiston was classified as "matter of fire." The theory stated that any material that was able to burn would release phlogiston during combustion and would stop burning when all the phlogiston had been released. When Scheele discovered oxygen, he called it "fire air" because it supported combustion. He explained oxygen in terms of the phlogiston theory, which he accepted.

Historians of science generally accept that Scheele was the first to discover oxygen, among a number of prominent scientists - namely, his contemporaries Antoine Lavoisier, Joseph Black, and Joseph Priestley. It was determined that Scheele made the discovery three years prior to Joseph Priestley and at least several before Lavoisier. Priestley relied heavily on Scheele's work, perhaps so much so that he may not have made the discovery of oxygen on his own. Correspondence between Lavoisier and Scheele indicate that Scheele achieved interesting results without the advanced laboratory equipment that Lavoisier employed. Through the studies of Lavoisier, Joseph Priestley, Scheele, and others, chemistry was made a standardized field with consistent procedures.

Legacy

In many ways, Scheele was far ahead of his time. Much of what he did had to be rediscovered because it was not appreciated by his immediate contemporaries. His insight into radiant heat and his discovery of chlorine gas are just two instances where his work was entirely glossed over and had to be rediscovered by others. He discovered oxygen before Priestley and Lavoisier, and this discovery became an essential stepping-stone toward invalidation of the long-held phlogiston theory. He made important forays into organic chemistry, a field that would not open up until 40 years after his death. Scheele was one of the pioneers of analytical chemistry. All of this was accomplished with a minimum amount of equipment, most of which he designed himself.

Although credit for many of his discoveries goes to others, and his name does not command the same level of recognition as many of his contemporaries, his accomplishments were of great importance to chemistry, and had a major impact on its development.

Hi,

The solution #3796 is correct. Good work, Monox D. I-Fly!

#3797. The sum of the squares of three consecutive natural numbers is 149. Find the numbers.

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The solution #3795 (two values) is correct. Neat work, math9maniac!

#3796. A two digit number is such that the product of the digits is 14. When 45 is added to the number, the digits are reversed. Find the number.

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#6669. What does the abbreviation SMTP signify? (Internet)

#6670. What does the abbreviation/acronym SWIFT signify? (SWIFT provides a network that enables financial institutions worldwide to send and receive information about financial transactions in a secure, standardized and reliable environment.)