Friday, November 23, 2012

The Bunsen Burner, Spectroscopy, and Geysers

Robert Bunsen (1811-1899)
Robert Bunsen deserves to be remembered for more than his "invention" of the Bunsen burner.  He was a brilliant chemist, and did work in spectroscopy, blast furnaces, batteries, and even geology.  One of the things that I like about writing this blog is seeing just how many pies these scientists managed to get their fingers in. They were curious, and made discoveries that, even if tangential to their regular work, are in many cases still remembered.  See my last post on Bohr for one example.  Probably Bunsen's most notable research out of the field of chemistry was his foray into geysers.  In the 1840s, on a trip to Iceland to study the recently erupted volcano Mount Hekla.  But he also became curious about the geyser there and did some measurements.  He came up with a theory about how geysers work, and did a demonstration with a model geyser to show that his theory worked.  That would have been a fun demonstration to see!

His early research was in organic chemistry, and he studied arsenic compounds and arsenic poisoning. He showed that iron oxide hydrate could be used as an antidote for arsenic poisoning, and also did extensive research into cacodyl compounds.  While still a young chemist, he nearly died of arsenic poisoning and lost the use of one eye from an explosion of one of his arsenic-containing compounds.  I have not found anyone to say why he discontinued his studies of cacodyl compounds, but I think it may have had to do with their obviously dangerous effects.  The results of his work helped Edward Frankland and Friedrich Kekulé in their studies of chemical valency. Bunsen also studied blast furnaces, which were of great importance in the 1830s due to the huge amounts of iron being produced.  He showed that over half of the fuel was lost, and worked with Lyon Playfair to improve the furnaces to be more efficient and to catch potentially useful byproducts.  This work resulted in his only book, Gasometry: Comprising the Leading Physical and Chemical Properties of Gases.

When Robert Bunsen became a professor at the University of Heidelberg in 1852, he took charge of a new laboratory building.  The building was equipped with gas, and during construction, Bunsen made suggestions to the building's mechanic, Peter Desaga, regarding the burners to be used.  There had been previous burners used, including one by Michael Faraday, but his was an improvement on these and enabled the flame to be hot, sootless, and non-luminous.  A biographer wrote at his death that "The Bunsen burner is now in use everywhere from the kitchen to the research laboratory." (Crew, p. 302) Not sure how it was used in the kitchen, but there you have it.

Bunsen and Kirchhoff's spectrometer
Though I could also write about his carbon-zinc battery that was much cheaper to make and longer lasting than the previous platinum covered plates, or his invention of the ice-calorimeter and the vapor calorimeter, I do want to talk about his spectroscopic work, which is perhaps most important, and led to the discovery of two new elements.  Bunsen's work with spectroscopy was done in collaboration with Gustav Kirchhoff (Kirchhoff's Law, anyone?), whom he met in 1851.  He had already been interested in light, such as the improvement of the gas burner and showing that an electric current could create light.  Kirchhoff joined Bunsen at Heidelberg and they formed, so it seems, a great team.  Bunsen's work with electrochemistry and batteries gave him the ability to separate metals, and the non-luminous burner that he had improved meant that he could use flame tests to see the different colors that metals gave off.  Kirchhoff suggested that the colors of different metals that had similar colors might be able to be distinguished by looking at the spectra with a prism.  They found that these spectra were unique to different elements.  When they noted a new spectral blue line, Bunsen hypothesized that it was a new element and went on to distill 40 tonnes of water to isolate 50 grams of a chloro-platinic coumpound, from which he identified this new element, which he called cesium, Latin for deep blue, from the blue line in its spectrum.  In 1861 he announced the discovery of rubidium, and thereafter others used his spectroscopic methods to discover and isolate thallium, indium, germanium, gallium, and scandium.

If you are not familiar with the principle of a flame test, or even if you are because it is always cool, the following video is a nice demonstration of the different colors that different metals are, and shows the spectral lines too.


I will conclude with a sad reminder to back up your data. Bunsen also studied the spectra of rare earth metals, and had just finished a large manuscript on the subject.  He left the manuscript on a table near a glass of water, and when he came back, he found the manuscript burnt.  It took him two years to replicate the data and apparatuses.  So the equivalent of hard drive crashes are nothing new.

Works by Bunsen
References


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Wednesday, October 3, 2012

Bohr's Dueling Discovery

Niels Bohr (1885-1962)
Unfortunately this summer I wasn't able to finish as many posts as I had hoped, so rather than a full post today, here is a tidbit.  As per the latest poll, up this week is Niels Bohr! But there is a lot to talk about, particularly with respect to the atom, so instead, I'll talk about something you probably didn't know. One of Niels Bohr's contribution to science derived from his love of western films. He noted that the bad guys always drew first, but the good guys always won, and wondered if it was actually the case that the person who drew second won more often. He went out and purchased some cap guns and "dueled" his friends to find out. Sure enough, always drawing second, he won. Recently, proving that Bohr didn't just have faster reflexes than his friends, Andrew Welchman at the University of Birmingham confirmed that the second person to draw is milliseconds faster to the trigger. So stick to your hobbies!  You never know where they may lead.

References
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Friday, August 10, 2012

John Dalton: Atoms, Weather, and Vision

John Dalton
1766-1844
Since one of my undergraduate degrees was in chemistry, I cannot believe that to this point I have only written one post that warranted the tag of "chemists." So this post is an attempt to remedy this. In looking at the lists of names that I have as potential subjects for blog posts, the first that jumped out at me were Henderson and Hasselbalch, famous for the equation for determining the pH of a buffer solution.  But I try to mix up the time periods that I write about, which either means that you, my readers, do not get bored or that you get horribly confused.  If it is the latter, I apologize.  I would have guessed that the Henderson-Hasselbalch equation was developed in the nineteenth century, but it ws actually in the 20th century, which eliminates them from consideration at the present time.  So instead, I have decided to write on John Dalton, of Dalton's Law of Partial Pressures, which you may (or may not) remember from high school chemistry. Dalton is also well known for his work in developing modern atomic theory.  Whether or not you know much about either of these topics, it is easy enough to find information on his contributions in these areas.  So I would like to focus in this post on two areas that receive less attention, his meteorological observations and studies on color blindness.

Dalton's System of Chemical Philosophy
Dalton's atomic and
molecular symbolism, from
A New System of Chemical Philosophy
Dalton’s interest in meteorology began while he was at school in Kendal, where he made the acquaintance of John Gough, who was nine years his senior.  It was he who first suggested that Dalton keep a meteorological journal.  Dalton made observations throughout his long life, including a measurement made the day before his death.  His first book of observations, Meteorological Observations and Essays, was published in 1793, with a second edition little changed from the first appearing in 1834.  While some of the book is simply his observations, he also included descriptions of many of the techniques used in making observations of the weather in use at the time.  He noted in the preface that “as the number of [barometers and thermometers] is increasing daily, many of them must fall into hands that are much unacquainted with their principles.”  In addition to writing about barometers, thermometers, hygrometers, thunderstorms, snows, winds, and the Aurorae Boreales, he also included essays regarding these phenomenon, particularly Aurora Borealis and its connection with magnetism.  It was his study of the atmosphere, a gas, that probably led to his interest in gases in general, which finally led him to his theories of atomic structure.  He also attempted to come up with the structures of many molecules, but was not always right since he didn’t know how much each atom actually weighed.  For instance, he thought that water was HO (one hydrogen atom and one oxygen atom) rather than H2O.

John Dalton also put much thought into color blindness, a condition that he suffered from. He gave a lecture at the Manchester Literary and Philosophical Society, of which he was a member, in 1794, describing the inconsistencies that he observed between how he saw color and how those around him saw colors.  He wrote to a friend that “the flowers of most of the Cranesbills appear to me in the day almost exactly sky blue, whilst others call them deep pink.” (The Worthies of Cumberland: John Dalton, p. 101) He also noted that his brother and he agreed on the colors of things, which to modern ears suggests that it was genetic color blindness.  Dalton suggested that the cause of the difference between  his vision and others was that the fluid in his eye was tinted blue.  As a true scientist, he suggested that his eyes should be dissected after his death to see if this was true.  It was not, but the eyes were preserved by the Manchester Literary and Philosophical Society and recently the DNA was examined, showing that Dalton lacked one of the three photopigments in the eye.  (If you wish to see the present state of his eyes and related images, I suggest you go to http://www.sciencephoto.com/set/803.) This theory of photopigments had been proposed by Thomas Young (1773-1829), one of Dalton’s contemporaries who established the wave theory of light, but even though Young’s view was more correct, color blindness has been historically called Daltonism. This just goes to show that you don’t have to be right to be remembered, you just have to be the first, or perhaps the clearest.

Selected Works by Dalton
References and further reading
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Sunday, July 15, 2012

Hans Geiger and the Geiger-Müller Counter

Hans Geiger (1882 - 1945)
The first SciHistory poll is responsible for the subject of this latest post, Hans Geiger.  I will try to always have a poll open, so when you stop by, vote!  And remember that you can always leave suggestion in the comments, even if it isn't at all relevant to the subject of the post.  But on to more serious business. (And I do apologize.  In rereading this post, it is kind of dull.)

Hans Geiger was born in Germany and received his PhD from the University of Erlangen in 1906.  After graduating, he went to England to work at the University of Manchester with Ernest Rutherford (1871-1937), who won the 1908 Nobel Prize in physics for his work with radioactive substances.  One of the first projects that Geiger collaborated on in Rutherford's lab was the famous gold foil experiment, also called the Geiger-Marsden experiment (Marsden was an undergrad working with Geiger) or the Rutherford experiment.  In this experiment, where helium nuclei (alpha particles) were fired at a thin sheet of gold, Rutherford hoped to better understand the actual composition of atoms.  When some of the particles deflected at very high angles, a reasonable explanation was that rather than having the mass of an atom spread fairly evenly, there must be a highly concentrated nucleus to an atom.  This experiment was vital to the modern understanding of the structure of the atom.

Geiger continued to work with alpha-particles, developing the first detector for alpha particles in 1908.  This consisted of a wire in a low pressure chamber with a voltage applied across the wire and the outside of the tube.  The voltage is high enough that a current can almost, but not quite, flow through the gas. When an ionizing particle came into contact with the wire, it disturbs the system enough to complete the circuit, and the resulting completion can be detected by an audible click or by a pointer, depending on the type of counter. Design variables included the applied voltage, the pressure inside the chamber, and the length and diameter of the tube. Geiger continued to try to make more sensitive devices, and in 1913, after returning to Berlin to work at the German National Institute for Science and Technology, created a more sensitive device that used a needle that stuck into the middle of the detecting tube, rather than a wire connected at both ends.  This version was able to detect both alpha and beta particles.

Geiger served as an artillery officer during World War I, and when he returned to direct radiation research at the University of Kiel and the University of Tübingen, and later at Technische Hochschule in Berlin. It was while working with a post-doc, Walther Müller, at Kiel, that the next breakthrough in the Geiger counter occurred.  Geiger wanted Müller to determine the precise effect of a positive ion on the counter, and in general to test different configurations, voltages, polarities, etc.  It was as a result of this that Müller discovered a configuration that lead to an increase in sensitivity of about 100 times, which is why in many publications and discussions of Geiger counters, one finds them called Geiger-Müller counters.  The increased sensitivity of this counter made them more useful for the detection of cosmic rays, which were a subject of much interest around that time.  They could also be combined with cloud chambers to watch electrons moving individually.

After this discovery, the sources that I have found don't talk about what Geiger did next much.  He continued researching radiation in various forms, including cosmic rays and nuclear fission.  He was involved in the German efforts to create a nuclear bomb, and died a few months after World War II ended.  What I find most interesting about his story is that he, more than many of the other people that I have written about so far, worked in collaborations.  The gold-foil experiment was done with Marsden, but the conclusions about the atom were Rutherford's.  The improved Geiger counter was the work of a student.  I think this way of doing research is much more what we are familiar with today, when papers can have ten co-authors and, especially as a graduate student, one's advisor's name is on everything.  Clearly, Geiger made important contributions, but he was not working alone.

Works by Geiger
References and Further Reading
  • "Hans Geiger". Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2012. Accessed July 13, 2012.
  • Thaddeus Trenn, "The Geiger-Müller Counter of 1928", Annals of Science 43, 2 (1986), 111-135.
  • "Geiger Counter", Lemelson-MIT Inventor of the Week, February 2005.
  • M. Walter and A. W. Wolfendale, "Early history of cosmic particle physics", The European Physical Journal H (2012). doi:  10.1140/epjh/e2012-30020-1
  • Paul Frame, "A history of radiation detection instrumentation", Health Physics 88, 6 (2005), 613-637.
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Friday, June 22, 2012

Arnold Sommerfeld: Father of Quantum Physicists

Arnold Sommerfeld
(1868-1951)
Arnold Sommerfeld is a man that I had not heard of until taking a course in solid state physics.  And I apologize to those of you who may hear the name with dread, but despite creating the Sommerfeld Equation, he really is an interesting guy, so please stick with me.  And I will only mention the Sommerfeld Equation one more time.  While he appears to have been known in his own time as a great mathematician and physicist, he is even better known by the students that he advised.  These include Werner Heisenberg, Wolfgang Pauli, Peter Debye, and Alfred Landé, among many others.  And these are just the students considered to be his advisees by the mathematics genealogy project.  Others famous men who studied with Sommerfeld include Linus Pauling, Léon Brillouin, and Rudolf Peierls.  He also has the unfortunate honor of being the man between 1901 and 1950 to receive the most nominations for a Nobel Prize without actually winning one, receiving eighty-one nominations.

Arnold Sommerfeld was born in 1868 in Germany, and studied mathematics and natural science at the University of Köningsberg, receiving his PhD in 1891.  He was an assistant professor at the University of Göttingen in mathematics and in mineralogy, before becoming a professor of mathematics at the Mining Academy of Claustel and then a professor of mechanics at the Institute of Technology of Aachen.  In 1906 he become the head of the Department of Theoretical Physics at the University of Munich, a position that had previously been held by Ludwig Boltzmann.  The University of Munich was well known in the field of theoretical physics, so this was both a great honor and a wonderful opportunity for Sommerfeld to influence a new generation of physicists.  He taught there from 1906 to 1935, when he retired.

When he receive the post of chair of Theoretical Physics, Sommerfeld wanted to learn more about the field, since he himself was a mathematician, not a physicist.  He asked Abraham Joffe, who had helped to discover x-rays, for help in understanding physics.  He suggested that they meet every morning at a café to discuss experimental physics, and these discussions quickly included many more scholars eager to discuss new ideas. Apparently he was a great lecturer, and was able to explain the complexities of atomic structure and other confusing topics with great clarity.

His research started out in the field of the propagation of radio waves, which now seems rather outdated, but at that time was of vital importance.  The telephone had been developed in the late nineteenth century, but by 1900, most people conveyed important communications by telegraph.  While telegraphs traveled by wires in many parts of the country, telegraphs to ships required radio waves, and the difficulties with sustaining a cable across the Atlantic meant that transatlantic communications would have to be by radio waves.  The first wireless telegraph was patented in 1897 by Guglielmo Marconi (who shared the Nobel Prize in physics in 1909 for his work with wireless telegraphy), and the first transatlantic telegraphic communications via radio waves were accomplished in 1901.  Sommerfeld's 1909 paper "The Propagation of Waves in Wireless Telegraphy" was thus of vital importance at the time, and has been oft cited.

As well as working with radio waves, Sommerfeld also worked with x-rays, still a very new and mysterious phenomenon, and his student Max von Laue showed that x-rays are also an electromagnetic wave (and won a Nobel Prize for it).  Sommerfeld went on to develop the relativistic quantum theory of the fine structure of the hydrogen spectrum.  Quantum theory is difficult enough, but adding relativity is quite an accomplishment.  I first met the name Sommerfeld when considering the electronic theory of metals, where he developed the Sommerfeld Equation as a method to approximate functions as a function of temperature. He is also famous for his work with atomic theory and atomic physics, in the end publishing a six volume series on the subject of theoretical physics and going on two lecture tours in the United States.  Unfortunately, however, he met his death as a result of an automobile accident in 1951.  As Linus Pauling wrote, "The hazard of a mechanized world has prevented his students from celebrating during his lifetime still further anniversaries of the birth of this great man."

Other works by Sommerfeld
  • "Über die Ausbreitung der Wellen in der drahtlosen Telegraphie (The propagation of waves in wireless telegraphy)", Ann. der Phys., 28 (March 1909), 665-736. (This is the same as volume 333.  They renumbered them in 2010.)  doi: 10.1002/andp.19093330402
  • "Über die Ausbreitung der Wellen in der drahtlosen Telegraphie (The propagation of waves in wireless telegraphy)", Ann. der Phys., 81 (December 1926), 1135-1153.  (Now volume 386) doi: 10.1002/andp.19263862516.

References and further reading
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Sunday, April 15, 2012

Svante Arrhenius: A Man of Many Interests

Svante Arrhenius
(1859 - 1927)
I'm sorry it's been awhile since my last post, but classwork caught up with me at last. I've been planning to write on Svante Arrhenius for two months now, when he came up in several homework assignments at the same time, and I expected this to be a simple post to write, since Arrhenius is best known, in my opinion, for his equation connecting the activation energy of a process and its kinetics. First, I found out that this was not the work for which he earned the Nobel Prize in Chemistry, and, more surprisingly, I discovered that he was also one of the first scientists to work out the effects of the greenhouse effect and he also postulated global warming resulting from human CO2 production. So between classwork, research, and Arrhenius being a more complicated person to write on than I though, this post has taken a while.  I will do my best to represent what Arrhenius actually wrote about global warming, but I can't read everything he wrote about the subject for this short post, so if you are curious, I would encourage you to look at some of his original writings, which are referenced and linked throughout.

Arrhenius was born in Vik, Sweden, in 1859.  His father was a land surveyor associated with the University of Uppsala, and the following year the family moved to Uppsala.  Here Arrhenius studied at the cathedral school, showing aptitude in mathematics.  He studied chemistry, physics, and mathematics at the University of Uppsala, but wanted a more rigorous physics education and went to Stockholm to study with Erik Edlund.  His work there resulted in his thesis, "Investigations on the galvanic conductivity of electrolytes."  This post's moral for graduate students is don't be discouraged if people think your ideas are wrong.  When Arrhenius submitted this thesis to the University of Uppsala, some of the professors were doubtful of its merit.  He proposed what is now universally accepted, that some chemical species dissociate in water into positive and negative ions, and that the degree of dissociation can depend on the concentration.  Michael Faraday (1791-1867) had already proposed ionic species, but only in the presence of an electric current.  In the end, his thesis was accepted.

One of the main proponents of his ideas was Wilhelm Ostwald (1853-1932), with whom Arrhenius was able to work as a result of a travel grant from the Academy of Sciences in the late 1880s.  He also worked with Ludwig Boltzmann (1844-1906), an Austrian physicist who was a proponent of the atom and a developer of statistical thermodynamics; Jacobus van 't Hoff (1852-1911), a Dutch chemist who studied, among other things, chemical kinetics and osmotic pressure; and Frederich Kohlsrauch (1840-1910), a German physicist also interested in the conductivity of electrolytic solutions.  Arrhenius's theory of electrolytes helped to explain some abnormalities in osmotic pressure data that van 't Hoff had found, and his discussions with these men enabled him to elaborate on his theory of dissociation to explain increases from the expected boiling point elevations and freezing point depressions in some materials by species dissociation.  These men were all instrumental in the formation of the modern field of physical chemistry. It was for this work, begun in his dissertation, that he won the Nobel Prize in Chemistry in 1903.

As I mentioned before, Arrhenius also studied the greenhouse effect.  The greenhouse effect, that the Earth's atmosphere can trap heat from the sun, had been proposed earlier by Joseph Fourier (1768-1830) in the 1820s.  John Tyndall (1820-1893), proved that both water and carbon dioxide can act as what we now call greenhouse gasses.  Arrhenius took their ideas and applied them to the question of whether the cycles of ice ages could be explained by changes in carbon dioxide in the air.  He did the extensive calculations to show that if the amount of carbon dioxide in the air doubled, the temperature of the earth would increase by five to six degrees Celsius.  He published these findings in the the Philosophical Magazine and Journal of Science under the title "On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground" in 1896.  He had worked with his friend Arvid Högbom (1857-1940), a professor of geology at the University of Uppsala, who had considered carbon dioxide cycles over time.  Arrhenius went further, and in his book Worlds in the Making (1908, p. 54), suggested that the burning of coal could be leading to an increase in carbon dioxide in the atmosphere, though much of it is absorbed into the oceans.

Arrhenius lived for thirty more years and did many more things, including being the head of the Nobel Institute for Physical Chemistry.  But, I've gone on for a bit about him already and hit some of the highlights, so I'm going to stop here.  If you are still interested in Arrhenius, you might want to look up his writings on popular science (including Worlds in the Making and Life of the Universe); his work on hydroelectric power, the electrification of the Swedish railroads, and immunochemistry; and his successful efforts to obtain the release of scientists made prisoners of war during World War I.  But to touch on those would mean more for you to read, and, more importantly, more for me to research, so I will leave Arrhenius with that.

Other works by Arrhenius


References and further reading

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Friday, February 17, 2012

Brook Taylor: Much More than a Series

Classes and research have been keeping me busy, so this post will also be on someone I have been tackling in my homework this week.  One of the main things that I have learned in graduate school thus far is that none of the equations we use are "correct."  They are all approximations of one sort or another, whether because we can't solve the real equation or because we can't take into account all of the interactions.  One of the most common tools for these approximations, when we have an equation but don't want to deal with it, is to use the Taylor expansion.  I hadn't given it or him much thought until this week, but they just keep popping up, so Taylor is this week's subject.

Modern chemistry seems to have developed in the 19th century.  That's when scientists finally agreed that atoms exist, and developed the modern concepts of energy and heat.  Mathematics, however, seems to have had a heyday in the 18th century based on the number of mathematical operators, functions, rules, etc. that have been named after the mathematicians of that century. These include Laplace, Lagrange, L'Hopital, Maclaurin, Euler, Gauss, Fourier, Legendre, and, of course (or else this interlude would be rather pointless), Brook Taylor.

Brook Taylor
(1685-1731)
In reading about Brook Taylor, I realized that, more than anyone I have discussed so far, I feel that I cannot do him justice.  This stems from two main causes: my lack of understanding of the finer points of mathematics and its history, and the number of interesting things that I discovered about Taylor.

Brook Taylor was an Englishman, born in 1685.  He went to St. John's College at Cambridge and studied mathematics, which was apparently quite popular in those days.  He began writing and publishing on mathematical subjects, but didn't publish soon enough after his discoveries to avoid trouble.  In 1708 he developed a solution to the problem of the center of oscillation.  I still haven't quite figured out what this is, but apparently it was a big deal.  He didn't publish his discovery, however, until 1713: De Inventione Centri Oscillationis.1

Meanwhile, Johann Bernoulli had independently come to the same discovery, and argued about precidence with Taylor.  In 1715 he published Methodus Incrementorum Directa et Inversa, which first introduced to the public what became known as Taylor's Theorem.  The work was also the first discussion of what came to be known as the calculus of finite differences, for more information on which you will have to ask a mathematician.  Taylor was not the first person to use the series, but he made the most general form of it.  Specific instances had already been used by Edmond Halley, Isaac Newton, Johann Bernoulli, and Johann Kepler.  The importance of the series was overlooked for many years, until it was pointed out by Joseph Lagrange in 1772.  Other problems that he solved in this book involved oscillations of a string and a change of variables formula.  He also write papers and letters on the subjects of magnetism, the movement of fluids, and logarithms.  His writing, however, suffered from a brevity that lead to confusion about what he actually meant, which led to his being under appreciated for all of the contributions that he made to mathematics.

In 1715 Taylor also published a work on linear perspective, followed in 1719 by New Principles of Linear Perspective, in both of which he used mathematics to explain linear perspective more generally than those before him had.  Bernoulli, with whom Taylor had already had heated arguments, declared that the book was "abstruse to all," especially artists.  Bernoulli's objections were so strong that Taylor wrote a reply in the Philosophical Transactions, Apologia D. Brook Taylor, J V D. & R S. Soc. contra V. C J. Bernoullium, Math. Prof. Basileae. I think Bernoulli had a point, though, since Taylor's works on perspective contained no sketches, just written descriptions, and even when he wasn't writing about art, he had a tendency to be concise to the point of confusion.

Taylor had been elected a member of the Royal Society in 1712, and had sat on the committee which adjudicated between Newton and Leibniz on the issue of which had invented calculus (they sided with Newton).  After about 1715, Taylor began writing more philosophical papers, such as "On the Lawfulness of Eating Blood."  His final paper in the Philosophical Transactions was "An Account of an Experiment, Made to Ascertain the Proportion of the Expansion of the Liquor in the Thermometer, with Regard to the Degrees of Heat," published around 1721.  He seems to have focused more on domestic matters and his health after that time, for in 1721 he also married.  His father disapproved of his wife, which suggests that Taylor, for one, married for love.  When she died in childbirth two years later, however, he and his father became reconciled.  In 1729 (1725?) he married again, but she also died in childbirth.  Taylor died just one year later.

1. Most articles I found said that it wasn't until 1714 that he published it, but I think this is the article in question, and according to Jstor it was published in 1713. So that is what I'm going with.

References and further information

Brook Taylor, 1911 Encyclopedia Britanica
Brook Taylor, from someone at the University of St. Andrews
Brook Taylor, by Edward Irving Carlyle, Dictionary of National Biography, 1885-1900, vol. 55.
Dr. Brook Taylor's Principles of Linear Perspective, edited by Joseph Jopling, 1835.
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Thursday, February 2, 2012

Diesel and His Engine

Rudolf Diesel
(1858-1913)
I've been hoping to find a scientist or engineer with an interesting story, and I think I found one. I was looking for information on how to synthesize monoglycerides, and discovered that the process is similar to making bio-diesel, which then begs the question (at least to me), what is diesel and why is it called that?

Rudolf Diesel invented the diesel engine, and thus in a remarkable fit of (probably) proper attribution, has his name attached to it. He is an interesting character, because he wanted to improve the efficiency of engines and change the world, a vision that I think few engineers really believe in today.

Diesel had a disjunct childhood.  He was born in Paris to Bavarian parents in 1858, but was sent to school in England in 1870 as a result of the Franco-Prussian War.  Less than a year later, he was sent to the Technical School in Augsburg, Germany.  He graduated from the Techincal University in that city in 1880, and began working with Carl von Linde (1842-1934) in Munich. Von Linde had recently developed a method for refrigeration using ammonia and was therefore very interested in the studies of heat.  In 1895, he even succeeded in liquefying air.1

Drawing from Diesel's apparatus for
converting heat into work,
US Pat. #542846
Working with von Linde, Diesel was able to work on a problem that he had begun considering when an undergraduate.  Steam engines were more efficient when large, so Diesel set out to develop an engine that would still be efficient when small. He was particularly interested in the ideal engine envisioned by Sadi Carnot (1796-1832) and descrived in 1824, called the Carnot cycle. At first, Diesel designed an engine similar to a steam engine that ran on ammonia, but, though the engine did work on a smaller scale than steam, he ran into problems like leakage.  He then considered a case in which the combustion of the fuel took place in a cylinder of the engine, rather than in a boiler.  Nikolaus Otto, a German engineer, had created the first marketed internal combustion engine in 1862, so this idea was not new.  What made Diesel's engine different was that it did not need a spark to ignite the fuel, but used higher compression ratios than the existing internal-combustion engines, leading to self-ignition. It was this isothermal combustion that set the diesel engine apart.

Diesel worked on models of the engine at the Augsburg-Nuremburg Engine Works with its financial backing and that of Krupp (a company that still exists today as ThyssenKrupp).  One of the greatest challenges was creating chambers that could withstand the large pressures that Diesel required for combustion. After four years of testing and various accidents, Diesel and his manufacturing aides created a working prototype engine in 1897. The engines got off to a rocky start.  Diesel tried to market his invention immediately, but there were still some kinks to work out.  Several accidents making dents in Diesel's profits from the patents he had taken out (see the list in references for more information).

Diesel had a larger vision for his engine than just making it more efficient. He thought that his engine could transform society. Since his engines worked on a smaller scale than the steam engines, they could be used by small craftsmen and help to counteract that increase in the scale of manufacturing resulting from the industrial revolution.  Diesel was part of a movement that believed that technology could save the world.  Rather than having the workers rise up as Marxism called for, he believed that technology could better the lot of workers and narrow the class divide, so such a revolution would not be necessary.  He did, however, believe in a form of communism in which workers would pool their resources for the greater common good.  He presnted his ideas in a 1903 book entitled Solidarismus: Natürliche wirtschaftliche Erlösung des Menschen (Solidarity: The Rational Economic Salvation of Mankind).  

In 1912, questions about whether Diesel actually invented the diesel engine came to a head.  Some people argued that credit needed to go to the factory assistants, rather than Diesel.  When a history of the diesel engine was to be published, Diesel preempted whatever it might say about him by presenting a paper explaining his development of the engine at the German Society of Naval Architects.  This might seem a strange place to give such a paper, but the main use of diesel engines at that point was in ships.

The following year, Diesel was crossing the English channel and went overboard during the night.  This incident led to much speculation about how he died, though the most likely explanation is that he committed suicide.  The most interesting story that I came across was that he was killed by the German secret service to prevent him from betraying secrets about submarines to the British.

1. Carl von Linde (back)

Holmgren, E. J., "Rudolf Diesel, 1858-1913" Nature 181, no. 4611 (1958), 737-738.
Bryant, Lynwood, "The Development of the Diesel Engine" Technology and Culture 17, no. 3 (Jul., 1976), 432-446.
Thomas, Donald Jr., "Diesel, Father and Son: Social Philosophies of Technology" Technology and Culture 17, no. 3 (Jul., 1978), 376-393.

List of Diesel's patents (back)
US Pat. #542846 Method of and Apparatus for Converting Heat into Work, filed August 26, 1892
US Pat. #608845 Internal-Combustion Engine, filed July 15, 1895
US Pat. #673160 Method of igniting and regulating combustion for internal-combustion engines, filed April 6, 1898
US Pat. #654140 Apparatus for Regulating Fuel-Supply of Internal-Combustion Engines, filed September 10, 1898
US Pat. #736944 Internal-Combustion Engine, filed November 1, 1899
US Pat. #RE11900 Internal-Combustion Engine, filed July 3, 1900
US Pat. #708029 Internal-Combustion Engine, filed January 18, 1901
US Pat. #873926 Longitudinally-Displaceable Car-Body for Motor-Vehicles, filed January 25, 1908
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Friday, January 27, 2012

Fick and Diffusion

Adolf Fick
(1829-1901)

I've been working on homework for a phase transformations class this week, and all of the problems have involved Fick's First and Second Laws of Diffusion, so he seemed to be a very obvious choice of subject this week.  Adolf Fick actually began his studies as a mathematician and physicist, but switched to medicine and got his PhD in 1851.  His thesis, rather than being on fluids as one might expect, was on astigmatism.  He taught at Zurich and then at Würzburg until his retirement.

I haven't been able to find anything about Fick's personal life except that he had a son, but he was quite active in his scholarly life.  He continued to apply the principles of physics and math to his study of medicine, and published works on how joints are articulated, where muscles get energy, how to measure blood pressure, how to measure how much carbon dioxide we exhale, and how we sense light and color.

I'd like to briefly introduce two of his inventions before returning again to diffusion.  He designed the first tonometer, which measures intraocular pressure (in the eye).  If you have ever been to an optometrist, they generally measure this now by puffing air into your eye.  Fick's method involved direct contact.  Using Fick's tonometer, one would press a plate against the eye and measure the force required to flatten the cornea to a specific diameter.  Fick's particular contribution was developing a mathematical way to converting the surface area of the contact between the eye and a plate and the force exerted on that plate into a measure of the pressure within the eye.  This relationship is often called the Imbert-Fick Law, since it was also discovered by Armand Imbert (1850-1922). The tonometer and Fick's studies of eyes led his nephew, also called Adolf Fick (1852-1937), to develop the first contact lenses in the late 1880s.1

Another of Fick's major contributions to medicine is known as Fick's principle or Fick's method.  I had never heard of these before researching this post, but perhaps those of you with a background in medicine will be more familiar with them.  Fick's principle provides a method for measuring cardiac output, or how much blood is being pumped by the heart.  He assumed that the rate at which oxygen is consumed is proportional to the rate of blood flow and the rate of oxygen absorption by red blood cells. By comparing the amount of oxygen in the blood entering and exciting the lungs, the rate of oxygen absorption can be measured, and from this the rate of blood flow can be deduced as being the rate of oxygen absorption over the difference in oxygen.  This principle can also be applied to blood flow through other organs, but as you can imagine, it is invasive and requires drawing and analyzing blood and oxygen consumption, but despite this, Fick's method is still referenced in literature today.

But back to diffusion.  Fick began his studies of diffusion after noticing that Thomas Graham (1805-1869), though he studied diffusion of salts in water and gases, had not developed a fundamental law describing diffusion.  Fick sought to rectify that.  He did not start from scratch, however, but recognized that the diffusion of atoms would be similar to the diffusion of heat.  Equations regarding heat transfer had been formulated in 1811 by Joseph Fourier (1768-1830). Fick pointed out that these equations had already been applied by Georg Ohm (1789 – 1854) to the diffusion of electricity in a conductor, so he set out to apply them now to the question of diffusion of liquids.  He published his paper On Liquid Diffusion in 1855 at the age of 26.

Top: Fick's equation
Bottom: modern equation
Fick's second law is the first equation on the right. He concluded his paper by saying that "such an hypothesis may serve as the foundation of a subsequent theory of these very dark phaenomena."2  On the whole, he was right.  The form of the second law has not changed from his initial statement except to be extended into three dimensions and to allow for the diffusion coefficient to be dependent on concentration.  The similarity can be seen in the second equation, which is that found in my textbook today.

I will leave you with that, and go and finish my diffusion homework.
[1] Mark, Armand Imbert, Adolf Fick, and their tonometry law, Eye (2012) 26, 13–16.
[2] Fick, On Liquid Diffusion, Philosophical Magazine, 10, no. 63, July 1855.
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Sunday, January 22, 2012

Schrödinger's Cat

While I try to write on people, this week I'll delve briefly into the subject of Schrödinger's Cat, which was raised by a comment on the introduction post (Thanks, Janet!).  I regret that I haven't gotten to the bottom of why Schrödinger picked a cat, but hopefully I can make the subject a little bit clearer, without saying something wrong.  I'm still trying to understand the nuances of quantum theory myself.

I usually try to have a picture to make the blog more interesting, but this time I'm going to start with a clip from the Big Bang Theory in which Sheldon explains the phenomenon of Schrödinger's Cat.

As Sheldon correctly states, Erwin Schrödinger (1887-1961) introduced his cat in a paper in 1935.  This was nine years after he had formulated his famous equation outlining the wave formulation of quantum mechanics. (That will undoubtedly be covered in more detail in a later post).  Below is the excerpt from the 1935 paper in which he describes the cat in the box, translated from the German.
One can even set up quite ridiculous cases. A cat is penned up in a steel chamber, along with the following device (which must be secured against direct interference by the cat): in a Geiger counter there is a tiny bit of radioactive substance, so small, that perhaps in the course of the hour one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube discharges and through a relay releases a hammer which shatters a small flask of hydrocyanic acid. If one has left this entire system to itself for an hour, one would say that the cat still lives if meanwhile no atom has decayed. The psi-function of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or smeared out in equal parts.
Schrödinger introduced this thought experiment to show the "ridiculousness" of the concept of blurring and his discontent with the lack of determinism in quantum mechanics.  These terms require some background knowledge of quantum mechanics.

But first, what you may be wondering, even if quantum mechanics isn't your cup of tea, so why a cat?  Did Schrödinger have a thing against cats, or did he have a pet cat so this was the first thing that came to mind?  I have no idea.  But I do know that the choice of a cat fits the parameters of the experiment very well.  He needed an animal that would fit inside his hypothetical steel box, so elephants are out, but that would also be quiet while in there so as to not give away its state of being before the box was opened.  I'm sure some would argue that a cat in a box would scratch, but just think how much noisier a bird or dog would be.  And lastly, the animal needs to be killed by the poison and be obviously dead or alive in the end.  The cat seems to fit all of these.  Personally, I think a rabbit might have done better, but as I'm rather fond of them myself, I'm happy to let Schrödinger have his thought experiment cat.

Now back to the details of the experiment.  Quantum theory had introduced the idea that electrons and other particles can only be in certain states, but not ones in between.  There is a modification to that, which is that particles can be in a situation called a superposition, where they are in two different states at the same time, though only one can be measured at a time.  The Copenhagen interpretation says that the wavefunction of the particle (or, using Schrödinger's words, the psi-function), gives the probabilities that, when measured, the electron will be in a certain state comprising the superposition.

The nature of this superposition is what Schrödinger is addressing in this thought experiment.  If the electron, or in this case the radioactive atom, is in two states at once, undecayed and decayed, the cat, whose life depends on the state of the atom, must also be in two states, corresponding to the two states of the atom.  This is referred to as entanglement (another term with lots of implications).  The idea that the cat is both alive and dead until we look in the box is obviously a problem, and shows Schrödinger's discontent with the probabilistic interpretation at the atomic scale.

One issue with the cat is the question of an observer and how measurements affect the wavefunctions.  When measurements are made of quantum systems, they always give a determinate answer-the electron is in one state or the other.  This is called the collapse of the wavefunction.  But if you sample an electron in the same state (though defining what is the same can be difficult), it will give different answers when you measure it multiple times.  If it is in an equal superposition of states A and B, when you measure it numerous times (returning it to the same starting state each time), it will say it is in A half the time and in B the other half.  When you ask the electron which state it is in by measuring it, you become an observer.  So in the case of Schrödinger's cat, whose life is tied to the state of the nucleus, is the cat an observer of the nucleus such that it forces the nucleus to no longer be in a superposition?  By this logic, though, if you are constantly measuring a radioactive element, will it ever decay?

So after perhaps raising more questions than I gave answers, that is the general gist of the cat.  I think one of the things that people often overlook is that this was a thought experiment proceeded by the phrase "one can even set up quite ridiculous cases..."  Schrödinger was not saying that this is what actually happens to the cat by any means.  He was using this to show that it he thought it was naive to think that electrons are smeared out over different states.

Even though few people, and I would not even consider myself to be one of them, understand the full implications of what Schrödinger was trying to say, his cat has caught the public imagination.  I here include several links to interesting more popular and humorous references to the cat.
Viennese Meow, a short story from the point of view of the cat
The story of Schroedinger's cat, an epic poem

And for those with a more scholarly bent, here are a couple of papers on the subject, from least to most scholarly.
Schrödinger's Cat, a better description and certainly better illustrated
How to Create Quantum Superpositions of Living Things
The death of Schrödinger’s cat and of consciousness based quantum wave-function collapse, Carpenter and Anderson, Annales de la Fondation Louis de Broglie, Volume 31, no 1, 2006.
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Friday, January 6, 2012

Celsius and the Centigrade

Anders Celsius
(1701-1744)
There is quite a bit of confusion in the United States about what the temperature is.  Today, for instance, I'd tell someone that it was forty-two degrees.  But if I told that to one of my international friends, she would look at me funny and, perhaps, begin working on a conversion from Fahrenheit.  Some true-blooded Americans also use the Celsius scale to give temperatures, as do most European countries.  But that isn't the end of it.  Some people, when asked which scale they just gave a temperature in, might say "centigrade," which just adds another term to the confusion.

The first part of this confusion originated in the eighteenth century, when two men, Anders Celsius and Daniel Fahrenheit, both developed thermometers with different scales.  Theirs were not the first, however. Galileo is usually credited with inventing the first thermometer, in 1592, but he did not develop a memorable scale to go with it.  In the seventeenth century, liquid thermometers were developed and could be made quite accurately, but no standard scale had come into use.  In the 1660s, Robert Hooke developed a thermometer scale that went from -7 to 13, and many other scientists also developed temperature scales.

Anders Celsius was a Swedish astronomer.  As a professor at the University of Uppsala, starting in 1730, he spent a lot of time making measurements.  In 1730 he published a paper on a new method of determining the distance of the earth from the sun, and in 1736 he participating in an expedition to Lapland to measure the arc of a meridian.  In conjunction with another expedition to Peru, this measurment confirmed Newton's theory that the earth bulges slightly in the middle.  He also measured the brightness of stars by seeing how many layers of a thin film it took before the light disappeared.  With the strength of these measurements behind him, he persuaded the University of Uppsala to let him build an observatory, which was completed in 1741.  This was the same observatory that Anders Ångström would be in charge of over a hundred years later.

None of those measurements would seem to necessitate having a thermometer, however, and this is in part because his job description as astronomer is different from what we think of today. Certainly measuring the distance of the earth from the sun falls under astronomy, but back in the eighteenth century, so did measuring distances like the arc of a meridian, the changes in the height of seawater, and more meteorological measurements, including temperature. Celsius developed his scale by setting the boiling point of water at 0 and the freezing point of water at 100.  He called the units "centigrade", because the distance between those points is divided into one hundred equal steps. This was not radical, as that was the way most scales were created--by choosing two points and putting a certain number of degrees between them.  Celsius took his study of temperature one step further. He was not content with just making a thermometer that worked in Uppsala, but wanted to better understand the nature of temperature and make sure that it was independent of location.  By making measurement in many places, along with measuring the atmospheric pressure, he determined that the freezing point, but not the boiling point, was independent of pressure, though neither depends on latitude.  He published a paper reporting his results entitled "Observations on two persistent degrees on a thermometer" in 1742.  He died only two years later of tuberculosis.

If you were paying attention when I mentioned what the two points of his scale were, you will notice that his scale went backwards from what it does today--the boiling point of water is 0 and the freezing point is 100.  The switched scale, as we know it today, was made popular by Carl Linnaeus, the Swedish botanist famous for originating the biological nomenclature used today.  He made measurements of the conditions in which plants grow, and for  him, the freezing point of water was vital, since many plants die below that temperature.  In a paper published in 1745, only a year after Celsius's death, he used the same size of a degree and the same fixed points as Celsius, but placed 0 at the freezing point of water and 100 at the boiling point.  The modern Celsius scale was born.  Well, not quite.

Celsius had called his scale the centigrade scale, and it continued to be called that for centuries.  It was not until 1948 that the Ninth General Conference of Weights and Measures renamed degrees centigrade degrees Celsius, and caused even more confusion.  So the next time someone says "degrees centigrade," they aren't wrong, per se, just outdated.

Sources and further information:
Temperature Scales from the early days of thermometry to the 21 st century
History of the Celsius Temperature Scale
Anders Celsius
Linnaeus' Thermometer
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Location: Uppsala, Sweden

Sunday, January 1, 2012

More than a Flask: Emil Erlenmeyer

An Erlenmeyer Flask
(Photo by Lucasbosch and
used under the CC licence)
When learning one's way about the laboratory and it's equipment, it is easy to see how glasswares such as the volumetric flask and graduated cylinder got their names.  The Erlenmeyer flask, however, is not at all descriptive, which perhaps stems from the fact that an easy name including a suggestion of its use or shape would be hard to come by.  Maybe a swirling flask, or a narrow-neck flask?  But whatever else it could be called, what has come down to us in the lab today is the name of the flask's inventor, Emil Erlenmeyer.

Emil Erlenmeyer
(1825-1909)
Erlenmeyer's full name was Richard August Carl Emil Erlenmeyer, so it is easy to see why he went with only Emil.  He began his studies as a chemist, and then turned to pharmacy in the 1840's and became an apothecary. Recall, however, that this was hardly a time of sophisticated medicine.  Florence Nightingale and her pleas for sanitation would not come until the next decade, and the effectiveness of the plethora of pills we have today was unheard of.

He returned to chemistry, however, and began on an academic career in German universities, studying at the University of Geissen and then becoming a professor at the University of Heidelberg.  I haven't been able to find a good story about how he created the Erlenmeyer flask, which he did in 1861, but since he was working in the lab experimenting with chemicals, it is easy to see why he did so. The shape has two main benefits: the shape, being wider at the bottom, makes it easier to swirl liquids without them splashing out, and the narrow neck reduces the amount of air exchange. He wasn't alone in working on improving laboratory equipment. Robert Bunsen, who had invented the Bunsen burner in the 1850s, was also a professor at the University of Heidelberg.

After invention of his flask, he had many more years to enjoy the fruits of his labors and the greater ease that the flask gave him in performing his experiments.  He published, according to a German website, at least twenty-seven articles, including several on cinnamic acid and other issues affecting organic chemistry.1   Another notable organic chemist was also working at Heidelberg when Erlenmeyer was there, August Kekulé, who was the first to write the structure of benzene as alternating double bonds.  The precise structure of molecules was a question that Erlenmeyer went on to study further.

Erlenmeyer's most memorable contribution to organic chemistry, though not as good for his name recognition as the flask, is "Erlenmeyer's Rule."  He developed this in the 1880s, by which point he was teaching at and retiring from the Munich Polytechnic School.  When I took organic chemistry, I don't recall this principle being called Erlenmeyer's Rule, though a quick literature search revealed that the name is still used.  Erlenmeyer's Rule says that if there is a hydroxyl group attached to a double bonded carbon, tautomerization will occur into the ketone or aldehyde form.  I wish I had known it had a name in organic chemistry, because I tended to forget this when writing the result of a reaction, and it would have been much better to blame it on a rule!

[1] DFG on Emil Erlenmeyer And if you are in Germany, you can register and read them for yourself! I, however, do not speak German and am now wishing that I did.
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Location: Munich, Germany
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