William Wollaston was an English scientist (chemist, physicist, and physiologist) who made contributions in each field. In 1813, he redesigned and improved the Volta’s pile. By joining cells of his battery he was able to construct very large batteries. He discovered the elements palladium and rhodium and first reported the dark lines in the spectrum of the Sun.
His consideration of geometrical arrangements of atoms led him into crystallography and the invention of the reflecting goniometer to measure angles of crystal faces. He also proved the elementary nature of niobium and titanium, developed a method of making platinum malleable, proved the identity of voltaic and frictional electricity, and invented the camera lucida to aid artists and microscopists. William Hyde Wollaston was born on August 6, 1766, in East Dereham, Norfolk, England, and during his life became a celebrated chemist, a natural philosopher, and a physiologist.
He was the son of vicar Francis and Althea (Hyde). He was educated at Charterhouse and at Caius College, Cambridge University (1782 to 1787). He received a degree in medicine in 1793, was immediately elected as a member of the Royal Society, and then began his medical practice in Huntingdon (London) in the same year. He also established a private laboratory to conduct research at the Royal Society in 1793, and became a foreign associate of the French Academy of Sciences. Between 1793 and 1797 he published several papers in science.
He became renowned in physiology. In 1797, he described the main components of urinary calculi. Then he suddenly gave up his medical practice in 1800 to devote time to pursue his dominant interest, scientific research. He became an associate of Humphry Davy at the Royal Institute. Wallaston was becoming partially blind about this time, also.
While working with Davy in 1809, he described a vibratory action of muscular activity. He identified a new type of bladder stone that he named “cystic oxide” (later called cystine) the first known amino acid in 1812, and then in 1824 he provided the best physiological description of the ear up to that time. He was a very careful experimenter in physiology.
In 1802 Wollaston developed the refractometer, an instrument for determining refractive indices with the aid of total reflection. The reflection goniometer for the measurement of reflecting surfaces followed in 1809. As a crystal goniometer, it is used to measure angles on crystals. The theodolite goniometer is a crystal goniometer with two graduated circles, one arranged at right angles on top of the other, allows angular measurements in one section and on all surfaces with the exception of the cemented surface without having to move the crystal.
Wollaston’s goniometer was a great improvement on the contactgoniometer, enabling more accurate measurements to be taken, affecting the interpretation of the structure of crystals. “This simple, cheap and portable little instrument has changed the face of mineralogy, and given it all the characters of one of the exact science.” (John Herschel, 1833)
Wollaston had verified the laws of double refraction in Iceland spar that had been studied by Huyghens, and from his work he wrote a treatise that he presented before members of the Royal Society on 24 June 1802.
First discovered in Iceland, but since found in several other locations, it is a clear form of calcite (a carbonate). To those who maintain that “there are no straight lines in nature, we refer to them to this specimen, characterized by straight lines and right angles. But its most unique characteristic is that it transmits a double image, demonstrating double refraction.
Then in 1803, he worked in optics and designed a dip sector (modified sexton) that was used by Ross and Perry while exploring the artic region. Around 1804 Wollaston established that visual acuity decreases when the wearer looks through the peripheral areas of biconvex eyeglass lenses. At the same time, he noticed that meniscus-shaped eyeglass lenses higher quality vision. Many ophthalmologists (including Ostwald and Tscherning) were looking for improvements, but their attempts were of little significance for practical use.
The Wollaston prism is a polarizing beam splitter, preserving both the O- and E-rays. It is usually made from calcite or quartz. The Wollaston prism is made up of two right triangle prisms with perpendicular optic axes. At the interface, the E-ray in the first prism becomes an O-ray in the second and is bent toward the normal. The O-ray becomes an E-ray and is bent away from the normal.
The beams diverge from the prism, giving two polarized rays. The angle of divergence of these two rays is determined by the wedge angle of the prisms. Commercial prisms are available with divergence angles from 15Â° to about 45Â°. They are sometimes cemented with glycerine or castor oil, and sometimes not cemented if the power requirements are high.
Wollaston lens was invented by William Wollaston in 1812, the design consisted of two plano-convex lens separated by a thin stop. Wollaston’s intention was to allow the lens to find a lens that would work with a wider aperture.
In 1830 Wollaston introduced an improvement upon his earlier design – a new doublet of two plano-convex lens separated with a stop. The plane sides of both lens faced the object, the shorter focal length on the bottom. The design further diminished aberration, and increased the resolving power.
In 1804, quite independently of Joseph von Fraunhofer, Wollaston discovered the absorption lines in the solar spectrum which are still used for determining chemical elements by spectral analysis to this very day. He improved the microscope and in 1807 developed the camera lucida, an optical apparatus used for drawing the outlines of objects.
W. H. Wollaston depicted in a drawing made by his own invention, the camera lucida.
Wollaston’s Camera Lucida
The Camera Lucida (Lucida is Latin for “light”), designed in 1807 by Dr. William Wollaston, was an aid to drawing. It was a reflecting prism which enabled artists to draw outlines in correct perspective. Consisting of an extendible telescopic tube in three pieces, with 45 degree prism and sighting lens, the lucida caught on in popularity quickly. No darkroom was needed. The paper was laid flat on the drawing board, and the artist would look through a lens containing the prism, so that he could see both the paper and a faint image of the subject to be drawn. He would then fill in the image.
The device was secured to the drawing table for stability. The unskilled artist was assisted greatly with the coming of Wollaston’s Camera Lucida. Nicholson’s Journal wrote in 1807 on the lucida (‘Description of the Camera Lucida, vol. 17, June 1807). This instrument should not be confused with nor compared to Hooke’s camera obscura which he had called a lucida. Durer (sighting tubes, grids) and Alberti (intersector) both used devices which allowed the ease of artistry.
William Wollaston first observed in 1802 dark lines in the solar spectrum which he incorrectly interpreted as gaps separating the colors of the sun. Then, Joseph Fraunhofer (1817) while working at a military and surveying instruments firm rediscovered the lines while calibrating the optical properties of glasses. He discounted Wollaston’s colour boundary interpretation, he observed a continuous color change across the spectrum; no color discontinuities occurred at the dark lines.
Fraunhofer later discovered dark lines in the spectra of stars and noted that some of the lines in stars were absent in the sun and vice versa. This clearly indicated that not all of the lines were of terrestrial origin. To his credit he did not taint his findings with deductive interpretations and confined himself to highly accurate empirical observations. Herschel considered that the Fraunhofer lines could either be caused by absorption in a cool gas in the earth’s or in the sun’s atmosphere.
Fraunhofer Lines. The dark vertical band in the spectrum of the sun represent particular colors of light that are missing.
Wollaston’s discoveries of platinum metals
Wollaston formed an association with Smithson Tennant to conduct experiments in chemistry. Platinum had eluded the efforts of chemists to produce it. Tennant tried to produce platinum, but ended up discovering the new elements of iridium and osmium. Wollaston’s effort, in turn, led him to the discovery of the new metals palladium (1803) and rhodium (1804). Wollaston named the metal Palladium (Pd) after Pallas (Athene), the second asteroid, discovered a year earlier. Pallas was the Greek goddess of wisdom.
A second new metal, Rhodium, was obtained by neutralizing the aqua regia with caustic soda. He then found the process to produce malleable platinum in 1805 which earned him considerable money by 1826, and which apparently compensated him more than had his medical practice. The success of his method, which he kept secret until shortly before his death, yielded him financial independence for the rest of his life. He waited until 1828 to present a paper describing the process of platinum to the Royal Society.
Palladium is a silver-white metal that is both ductile and malleable. It is more prone to attack from common acids than other platinum metals. The other platinum metals hardly respond to hydrochloric acid at room temperature. Palladium has an unusual tendency to pick up such gases as hydrogen, and oxygen. Palladium can absorb hydrogen up to 900 times its own volume. It is fairly reactive chemically and readily forms metallic compounds.
Commercial applications of palladium include its use:
– as a “stiffener” when used with gold in silver in dental inlays and bridgework,
– as a substitute for silver jewelry,
– as springs in analog wristwatches,
– in contacts for telephone relays and high-grade surgical instruments,
– in alloys for special systems,
– as a catalyst in synthetic organic reactions.
Rhodium is a platinum metal and shares some of the notable properties of platinum, including its resistance to corrosion, its hardness and ductility. Wherever there is platinum in the earth, there is rhodium as well. In fact, most rhodium is extracted from a sludge that remains after platinum is removed from the ore. A high percentage of rhodium is also found in certain nickel deposits in Canada.
Rhodium has a very high melting point and good electrical conductivity. These properties make it suitable for high temperature alloys, electrical devices, and furnace windings. Other uses include its use in the manufacture of special high temperature crucibles for laboratory applications. It is also a good hardener for platinum and palladium. Rhodium also makes a lustrous, hard coating for other metals in such items as table silver and camera parts. A thin film of rhodium deposited on glass makes excellent mirrors.
Wollaston was said to resemble Cavendish in temperament and mental habits. He was pleasant in appearance, very polished and gentle in manners, and clear in conversation. He was gifted with spirit of justice and moderation in views so that it became a proverb that whoever argued with Wollaston was wrong!
Wollaston became a Fellow of the Royal Society between 1797 and 1800. He created an endowment with the Wollaston medal to be awarded annually by the Geological Society, London, for outstanding research mineralogy. In 1802 he received the Copley medal of the Royal Society.
In 1806, Wollaston was elected Secretary of the Royal Society, and over the years contributed to all 39 “Memoirs” of the society in Philosophical Transactions. He later served as its president (1820-1828) when succeeding Banks as president of the Royal Society in 1820. Sir Joseph Banks became president of the Royal Society in 1778 and served until 1820 at which time he picked Wollaston for president rather than Michael Faraday who wanted the job.
Then in 1808, Wollaston experimented on carbonates, sulfates, and oxalates to show how they conformed to the law of multiple proportions. In a paper of 1812, he mentioned that spherical particles consisting of mathematical points surrounded by forces of attraction and repulsion could explain the structure of crystals that he had been studying. Later, Faraday accepted Wollaston’s explanation (theory of unextended point centers of force) rather than the theory of atoms by Dalton.
Wallaston designed a logarithmic slide rule for expressing the proportions of common chemical substances combined (standard oxygen unit of 10). The slide rule was used in chemistry for more than 20 years.
Wollaston’s contributions to electricity
While Gautherot, Ritter, and Van Marum were working with the newly discovered pile of Volta in 1800, William Wollaston, also at the same time, performed experiments resulting in similar contrasts between galvanic and static electricity. He then confirmed van Marum’s work by demonstrating that copper obtained from a copper sulfate solution could be deposited on the wire connected to the negative pole of an electrical machine similarly to that of the pile.
He next decomposed water using the Leyden jar, and found that the difference between galvanism and the Leyden jar was that galvanism was less intense but of better current quality. Then in 1801, Wollaston complemented Ritter’s work by decomposing sulfur sulfate solution when a wire was placed through each end of the vessel and into the solution while the other ends of each wire were connected to a frictional electrical machine.
Wollaston was the first scientist to outline the differences between the new galvanic current and that of the standard frictional current when he presented a paper before the Royal Society in June 1801. He showed convincingly that the pile of Volta was electrical, had less tension (later called volts), but more quantity (later called current) than that of frictional electricity.
This paper also revealed that he had decomposed water using galvanic current. He believed that the decomposition of water depended on the proportioning of electrical charge to a specific quantity of water, and that the discharge of current on the surface of a substance depended on the size of its surface. He learned that a piece of silver when connected with the positive pole of a pile and put into a solution of copper would become coated with the copper. This coating was found to withstand the operation of burnishing (polishing a surface by friction).
Wollaston made improvements to the galvanic pile in 1813 or1815. In Wollaston’s battery the copper plates were doubled (a copper plate bent round into a U-shape) with a single plate of zinc placed in the center of the bent copper. The zinc plate was prevented from making contact with the copper by pieces or dowels of cork or wood. In his single cell design, the copper U-shaped plate was welted to a horizontal handle for lifting the copper and zinc plates from the activating solution when the battery was not in use.
The metal plates and the solution were contained in an earthenware vessel. His design was the best battery at the time. In 1801, he determined the polarity of the pile. When he placed litmus in the water the positive pole of the pile turned the paper red. Acid and afterwards the negative pole turned the water blue with the litmus (alkaline) in the same area that was once red.
Wollaston also put several separate cells in a series to form larger batteries. In these batteries the metal plates in each cell were welded to a single overhead bar (replacing the single handle arrangement) that was then mounted to two adjustable ring stand type uprights. This unit formed a trough, and was considered an elementary galvanic cell.
He experimented with element sizes until he found that one inch square was sufficient to ignite a wire of platinum one three thousandths of an inch in diameter. The solution used in the cell by Wollaston was sulfate of copper (Zn + CuSO4 = ZnSO4 + Cu). This chemical reaction left a deposit of copper as a black powder (oxide of copper) on the zinc plate which then had to be constantly scraped off in order to maintain an acceptable current amplitude.
Wollaston in the meantime also learned about Oersted’s discovery of electromagnetism and reasoned that Ampere’s circular currents of electromagnetic action were the result of helical current revolving around its own axis when a permanent magnet was close to the wire. Wollaston may have been the first to suggest the idea of electrical magnetic rotations (1821). Wollaston conducted some experiments and then told Davy about them. Then in April 1821, he and Davy tried the experiments in the laboratory at the Royal Institution. Their experiments failed to show rotations of electromagnetic currents.
Wollaston went on to show attraction and repulsion moving in opposite directions around a wire carrying current, but he never was successful in demonstrating electromagnetic rotation. Arriving in the laboratory one day when Davy and Wollaston were supposedly discussing the experiments of Wollaston who was still working at the Royal Institution along with other scientists, Michael Faraday (Davy’s assistant) apparently entered the room and went about his usual laboratory activities without communicating or remaining in the room with Davy and Wollaston.
In the summer of 1821, Faraday began conducting his own experiments on magnetism, and by September had observed that a wire carrying current would rotate around a magnet when placed above the magnet. Faraday published the results of his experiments in the October 1821 issue of Quarterly Journal of Science. Rumors soon circulated that Faraday had stolen Wollaston’s idea. Faraday was later accused of applying the contents of the conversation to his personal benefit in discovery of electromagnetic rotation. Being aware of the rumors and accusation, Faraday after awhile invited Wollaston to his laboratory to observe several experiments. After observing Faraday and his experiments, the rumors stopped and Wollaston was convinced that his idea had not been stolen.
Since Faraday never entered anything about electromagnetism in his diary for that day, history records him as not overhearing Davy’s and Wollaston’s discussion on electromagnetism. Apparently Faraday’s thinking at the time was preoccupied by experiments in chemistry and the courtship of his girlfriend. History also records the story as possibly being started by Davy, since he was a very greedy and jealous individual.
The amount and variety of his research made Wollaston one of the most influential scientists of his time. Of his 56 papers in chemistry, mineralogy, crystallography, physics, astronomy, botany, physiology, and pathology, many represented notable scientific advances.
Wollaston died in London on 22 December 1828.
The mineral Wollastonite was named in the honor of Wollaston. Wollastonite is a common mineral in skarns or contact metamorphic rocks. Skarns can sometimes produce some wonderfully rare and exotic minerals with very unusual compositions. However, wollastonite has no unusual elements in its chemistry and it is somewhat common and not considered very exotic among collectors.
Wollastonite is formed from the interaction of limestones, that contain calcite, CaCO3, with the silica, SiO2, in hot magmas. This happens when hot magmas intrude into and/or around limestones or from limestones chunks that are broken off into the magma tubes under volcanoes and then blown out of them. The mineral is formed by the following reaction:
CaCO3 + SiO2 —-> CaSiO3 + CO2