Month: October 2018

1796: The First Vaccination

Posted on by Dan

Humanity has achieved countless medical breakthroughs over the centuries, yet few have had as profound and lasting impact as the invention of the first vaccine.  A vaccination is the process of administering biological preparation called a vaccine to stimulate the immune system and protect individuals from infectious diseases.  The primary purpose of the vaccine is to mimic the infection without causing the disease, although sometimes mild symptoms will occur for a brief period of time.  This will prime the immune system to recognize and respond effectively later if the person is exposed to the actual infection.

This remarkable achievement was first performed by the English physician Edward Jenner in 1796.  Despite recent controversies over vaccinations, this medical breakthrough had led to the prevention of many diseases and has undoubtedly saved countless lives.  

Edward Jenner and the Smallpox Threat

This first vaccination was developed against smallpox, a disease that had plagued humanity for thousands of years.  This highly contagious and often fatal disease caused high fever, severe skin rashes, and the formation of fluid-like blisters on the skin.  Smallpox had a mortality rate of up to 30%.  Outbreaks were common, leading to the loss of millions of lives.  Edward Jenner, an English physician and scientists, made his revolutionary discovery late in the 18th century when he developed a vaccine for smallpox.

Edward Jenner Vaccination
Edward Jenner Administering the First Vaccination

Earlier in the 18th century it was observed that people who suffered from a more benign form of cowpox became immune to smallpox.  Jenner had also observed that milkmaids who had contracted and subsequently recovered from cowpox did not appear to contract smallpox.  These observations led Jenner to hypothesize that the cowpox infections somehow helped to protect these people against smallpox.  In 1796 Jenner tested his hypothesis.  He took cowpox material from Sarah Nelmes, a milkmaid, and injected it into the arm of an eight year old boy, James Phipps.  The boy became sick for a few days but soon recovered.  Two months later he was exposed to smallpox and showed immunity to the disease, which lasted for the rest of his life.  It was the proof Jenner was needed.  He had successfully developed worlds the first vaccination, the word derived from the Latin word vacca, which means cow.

Two years later Jenner published An Inquiry into the Causes and Effects of the Variolae Vacciniae, which outlined Phipps vaccination as well as twenty two related cases.  Jenner’s publication soon generated much interest on the topic after subsequent vaccinations were reproduced by others.  His work laid the foundation for the science of immunology, leading the development of vaccines for many other diseases.  Over the coming decades advancements in microbiology and immunology led to the development of vaccines for several diseases, including polio, influenza, measles, mumps, rubella, HPV, and many others.  

Most recently the COVID-19 pandemic, caused by the SARS-Cov-2 virus, highlighted the need for vaccines.  In a remarkably short time multiple vaccines were developed and authorized for emergency use to combat the pandemic.  Governments launched vaccination campaigns globally to control the spread of the disease and reduce its impact on the public health.  

A Long-Lasting Global Impact

Jenner’s discovery of the vaccination was nothing short of revolutionary. Within a few years vaccinations spread around the world and were being endorsed by governments. As early as 1801 Russia supported the use of vaccinations and in 1802 Massachusetts became the first state to actively support their use as well. Today vaccinations provide a variety of public health benefits.  These benefits include:

  1. Disease Prevention:  The primary purpose of vaccines is disease prevention.  They work by stimulating the immune system to recognize and fight specific pathogens, reducing the likelihood of infection.
  2. Reduced Morbidity and Mortality:  Vaccines reduce the incidence of diseases, hospitalizations, and deaths.  Additionally, after a large enough portion of the population is vaccinated, herd immunity is achieved, protecting even those who have not been vaccinated.
  3. Elimination of Diseases: Vaccinations have played a paramount role in the elimination or near elimination of many diseases, beginning with smallpox.  In 1980, the world was officially declared free from this deadly disease.  Polio is another disease on the verge of elimination.  
  4. Various Economic Benefits:  By preventing illnesses, vaccines reduce healthcare costs associated with treating infectious diseases.  They also minimize lost productivity due to illness in the workplace.
  5. Prevention of Outbreaks:  Vaccines are critical in preventing outbreaks of infectious diseases.  

It is because of these and numerous other benefits that vaccines are considered one of the most successful and cost-effective public health measures.

Continue reading more about the exciting history of science!

Joseph Black

Posted on by Dan
Joseph Black portrait
Joseph Black

Joseph Black (1728 – 1729) is considered the father of quantitative chemistry and his research on boiling and freezing liquids revolutionized our understanding of heat.  He is best known for his discoveries of carbon dioxide and latent heat.

Born in Bordeaux into a large family of Scottish wine traders, Black was educated at the University of Glasgow where he studied medicine quickly took a liking to chemistry after attending the chemistry lectures of William Cullen.  In 1752 Black transferred to the University of Edinburgh to finish his medical studies.  His medical thesis turned out to be one of the most important scientific papers in the history of chemistry.  It centered what happened when a from of magnesium carbonate was heated.  He ended up isolating the gas given off, carbon dioxide, but the real importance in his paper was that it was the first instance where anyone was taking careful, precise measurements in chemistry.  This paper and his follow up lectures on it laid the basis laid the foundation for quantitative chemistry.

After obtaining a professorship at Glasgow, Black took up research on the nature of heat.  By exploring phenomenon that there is no temperature change in a phase change, such as solid to liquid or a liquid to a gas, he came up with the notion of latent heat.  Latent heat is then the thermal energy released or absorbed by a substance during its phase change. Heat water at 100 degrees Fahrenheit and its temperature will continually increase until the boiling point of 212 degrees Fahrenheit.  Continue adding heat the the water and its temperature will stay at 212 degrees, while some it evaporates as gas.  This is because all the energy added to the boiling water is being absorbed as latent heat of vaporization.  When James Watt began working at Glasgow University the two became friends and Black shared his ideas on latent heat, which Watt surely used to improve his steam engines powered the industrial revolution.

Black eventually succeeded William Cullen as Professor of Medicine and Chemistry at the University of Edinburgh where he was a superb lecturer.  For thirty years held this position until his failing health forced him to retire.

Joseph Priestley

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Joseph Priestley portrait
Joseph Priestley

Joseph Priestley (1733 – 1804) is usually credited with the discovery of oxygen, which helped to overthrow the phlogiston theory that attempted to explain oxidation processes.

Priestly was born in Bristal Fieldhead, England into a family with a strong religious influence.  Throughout his life he had no formal scientific training but his interest in science was aroused when he met Benjamin Franklin in London in 1766 and had discussions with him about electricity.  He took to the subject quickly and the next year published a 700 page work, The History and Present State of Electricity, which went through five successful editions.

The work for which Priestley is most famous for was done in 1774.  He would use a lens to focus sun rays to heat various chemicals and observe what gases they would emit.  When he focused the sun rays on mercuric oxide he was able to capture the gas emitted.  He tested this new gas on mice and noticed they would live much longer entrapped with this gas than with an equal amount of air.  The gas was not soluble in water and candles burned much longer in it too.  He had discovered oxygen.  This work combined with that of Antoine Lavoisier’s further experiments helped to overthrow the theory of phlogiston.

Although Priestly was raised as a devoted Calvinist he came to reject those beliefs and increasing came to hold unpopular religious beliefs.  In the last decade of his life he fled England to the United States where he lived his final days in a more tolerant religious environment.

1897: Electron

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An atom showing its protons, neutrons, and electrons.
Nuclear Structure of the Atom

The atomic theory of the atom was proposed by John Dalton in the early 19th century. Dalton claimed that all atoms of the same element are identical, but that atoms of different elements vary in size and in mass. His theory suggested that atoms were indivisible particles, making them the smallest building blocks of matter. However by the middle of the 19th century, a growing body of experiment evidence began to challenge this notion. As the century drew to a close some scientists that speculated that atoms may be composed of additional fundamental units, and by the late 19th century convincing evidence began to emerge from experimental research to support this hypothesis.   The discovery of the electron was the first of a series of discovery’s, spanning a few decades, that identified the major subatomic particles of the atom.

J. J. Thompson’s Experiments

This experimental evidence came during the years 1894-1899 when J. J. Thomson conducted research with cathode ray tubes, the same technology that also played a critical role in the discovery of X-rays and on work which led to the discovery of radioactivity.  Cathode rays are the currents of electricity observed inside a high vacuum tube.  When two electrodes are connected to each end of the tube and voltage is supplied, a beam of particles flows from the negatively charged electrode (the cathode) the positively charged electrode (the anode).  In a lecture to the Royal Institution on April 30, 1897, J. J. Thomson suggested that these beams of particles were smaller, more fundamental units of the atom.  He termed them ‘corpuscles’ but the name never stuck, and they were eventually given name we are familiar with today: electrons. 

J. J. Thomson's cathode ray tube used to discover the electron
J. J. Thomson’s cathode ray tube used to discover the electron
(Credit: Donald Gillies)

J.J. Thomson performed several experiments whose conclusions supported his hypothesis.  Firstly, in 1894 Thomson established that cathode rays were not a form of electromagnetic radiation, the assumption at that time, by showing that they much move slower than the speed of light. Soon after he conducted experiments deflecting the rays from negatively charged electric plates to positively charged plates where he was able to show that the beams were streams of negatively charged particles.  In another experiment he used magnets to deflect the beams which allowed him to determine their mass-to-charge ration.  He approximated their mass at 1/2000th of a hydrogen atom indicating that they must be only a part of an atom.  This is an incredibly small mass and is the smallest measured mass of any particle that has mass.  Lastly, he showed that these particles are present in different types of atoms.

Diagram of a cathode ray tube
Diagram of a cathode ray tube

The revelation that atoms are made of smaller constituent units revolutionized how scientists viewed the atom world and spurred research on nuclear particles.  Soon after the atomic nucleus was discovered, and the field of nuclear physics was born.  Thomson went on to create one of the first models of the atom, which was called the plum pudding model.  He knew that atoms had an overall neutral charge.  Therefore, his model depicted the negatively charged electrons floating in a “soup” of positively charged protons.  It was a good first attempt at designing a model of the atom but was soon discarded for Ernest Rutherford’s nuclear model of the atom based on the results of his gold foil experiment.  

Impact and Legacy

The discovery of the electron had profound effects on both theoretical and applied science.

The discovery of the electron helped to usher in the era of atomic physics and help to give birth to the completely new and foreign field of quantum mechanics.   Both of these fields are closely related and describe the behavior of particles at the atomic and subatomic level.  Both fields rely on an understanding of atomic structure, of which electrons are a key component.

The discovery of the electron also had a fundamental impact on applied science as it laid the foundation for the development of electronics, a technology that would revolutionize our world.  Electrons, being charge carries, are the fundamental working units of electronic components such as capacitors, diodes, resistors, and transistors.  They are used in all of the familiar electronic devices such as televisions, smartphones, and computers and have made possible the digital transformation of our civilization. In addition to electronics, electrons are involved in atomic spectroscopy, which is the study of the interaction between light and matter. By studying energy levels and transitions of electrons, atomic physicists can identify elements, determine their properties, and study their behavior in various conditions. Spectroscopy is the method used by astronomers to determine the temperature, chemical composition, luminosity, and other characteristics of distant stars across the universe.

Continue reading more about the exciting history of science!

Joseph John Thomson

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Joseph John Thomson (1856 – 1940) was an English Nobel Laureate who made key contributions to the field of physics.  Most notably he is credited with discovering the electron.

The Life of J. J. Thomson

Joseph John Thomson
J. J. Thomson

J.J. Thomson was born in Cheetham Hill near Manchester in England.  His father planned for him to be an engineer, but when an apprenticeship couldn’t be found he was sent to Owens College at the young age of fourteen.  There he obtained a small scholarship to attend Trinity College, Cambridge where he obtained his Fellowship, received his Master of Arts degree, culminating in the Cavendish Professor of Physics at the University of Cambridge.

While at the University of Cambridge, Thomson did important research to advance our understanding of the atom.  Most important he was one of the first to suggest that the atom may be composed smaller, more fundamental units.  He carried out research with cathode rays, which are beams of light the follow from electrical discharge in a vacuum tube, that led to the discovery of the electron.  From his experiments, he was able to at which these rays were deflected by a magnetic field and to calculate the ration of the electrical charge to the mass of the particles.  What he discovered was that this ratio was always to same no matter what gases were used, and thus he determined that the particles making up the various elemental gases must be the same.

Along with discovering the electron Thomson was the first to determine that each hydrogen atom has only one electron.  He was pivotal in inventing the mass spectrometer which assisted in chemical analyses.  Thomson received various awards for his scientific achievements throughout his life including a Nobel Prize in physics in 1906.  He was knighted in 1908.  JJ Thomson died in 1940 at the age of 83 and was buried in Westminster Abbey with many other scientific greats.

Continue reading more about other impactful scientists!