Electromagnetism
His experiments on electromagnetic rotation and induction helped establish foundations of modern electrical technology.
NANOSCIENCE HISTORY
Michael Faraday and the Early Science of Colloidal Gold
Long before the terms nanoparticle and nanotechnology entered modern scientific language, Michael Faraday investigated ruby-coloured liquids containing finely divided gold particles that were too small for the scientific instruments of his time to resolve directly.
His nineteenth-century experiments connected finely divided gold, colour and the behaviour of light, becoming an important early chapter in the history of colloid science and nanoscale materials research.
1856
Historic Gold Colloids
1857
Published Gold Research
Light
Used to Study the Particles
Preserved
Historic Samples Survive
EARLY GOLD COLLOID SCIENCE
Why Faraday's Gold Experiments Still Matter
Faraday's gold colloids are among the earliest documented examples of metallic gold colloids and remain an important part of the history of colloid science and nanoscale materials research.
At the Royal Institution in the mid-1850s, Faraday was investigating thin films of gold and their interaction with light. During this work he encountered faint ruby-coloured fluids containing finely divided gold, preserved samples of them and continued investigating their optical behaviour.
Faraday could not resolve the suspended particles directly with the scientific instruments available to him. Instead, he studied colour, transmitted light, scattered light and changes between different preparations to investigate the physical state of the gold.
THE SCIENTIST BEHIND THE EXPERIMENTS
Who Was Michael Faraday?
Michael Faraday was one of the most influential experimental scientists of the nineteenth century. His work made major contributions to electromagnetism, electrochemistry and the experimental study of electricity and matter.
His investigations of electromagnetic rotation and induction helped establish principles that underpin electric motors, generators and transformers. His electrochemical research also helped establish quantitative relationships between electricity and chemical change.
Faraday was especially skilled at using carefully designed experiments to investigate physical effects that could not always be observed directly. That approach became particularly important when he studied finely divided gold and its unusual interaction with light.
Electrochemistry
His research helped establish quantitative links between electrical charge and chemical change.
Fields and Forces
His experiments helped reshape scientific thinking about electricity, magnetism and forces acting through space.
Gold Colloid Research
His experiments with finely divided gold became an important early contribution to the study of colloidal and nanoscale materials.
THE PHYSICS OF COLOUR
Why Can Gold Colloids Appear Red or Ruby Red?
Bulk gold is familiar as a metallic yellow material, but finely divided gold can interact with visible light in very different ways. This is why some gold colloids can appear red, ruby red, purple or other colours rather than metallic yellow.
For nanoscale gold particles, modern science describes an important part of this optical behaviour using localised surface plasmon resonance. Conduction electrons within the particles can respond collectively to the electromagnetic field of incoming light, influencing which wavelengths are absorbed and scattered.
The resulting colour depends on several characteristics of the dispersion, including particle size, shape, distribution, aggregation, concentration and the surrounding medium. Under certain conditions, finely dispersed gold can produce the red to ruby-red appearance associated with some of Faraday's historic preparations.
Particle Characteristics
Particle size, shape, distribution and aggregation can all influence the optical behaviour of a gold dispersion.
Interaction With Light
Nanoscale gold can absorb and scatter visible wavelengths in ways that differ markedly from bulk metallic gold.
Red to Ruby-Red Appearance
Certain particle characteristics and dispersion conditions can produce the striking red or ruby-red appearance associated with finely divided gold.
INSIDE FARADAY'S EXPERIMENTS
What Faraday Actually Investigated
Faraday's importance was not simply that his experiments produced unusual coloured gold preparations. He investigated how gold in highly divided forms behaved and how those preparations interacted with light.
His work included thin gold films and gold-containing fluids with different colours and optical characteristics. By preparing, altering and comparing these materials, he explored relationships between the physical state of gold and its interaction with light.
1857
Philosophical Transactions
THE BAKERIAN LECTURE
Experimental Relations of Gold (and Other Metals) to Light
Faraday's paper was received by the Royal Society in November 1856, read in February 1857 and published in the 1857 volume of Philosophical Transactions. It documented his investigations into gold and other metals, including the striking optical behaviour of finely divided gold.
An Experimental Programme Built Around Observation
Without the imaging and analytical instruments available to modern materials scientists, Faraday relied on preparation, alteration, comparison and optical observation to investigate material that he could not directly resolve.
Prepare and Compare
Faraday examined gold in different preparations, including thin films and finely divided material, and compared changes in colour and physical appearance.
Observe the Light
He examined how light was transmitted, reflected and scattered by different preparations, using optical behaviour to investigate the material within them.
Interpret the Changes
Differences in colour and optical behaviour helped Faraday reason about changes in the physical state and degree of division of the gold.
THEN AND NOW
What Faraday Could Observe and What Modern Science Can Measure
Faraday could investigate finely divided gold through visible changes in colour and the behaviour of light, but the scientific instruments available in the nineteenth century could not directly characterise the individual suspended particles. Modern analytical techniques allow researchers to examine many of those material properties in far greater detail.
Behaviour Visible Through Experiment
- Differences in colour between gold preparations.
- How light was transmitted through or scattered by different preparations.
- Differences between gold prepared or treated in different ways.
- Changes in colour and optical behaviour when a preparation was altered.
- Visible evidence that the physical state of finely divided gold affected its interaction with light.
Properties Modern Instruments Can Measure
- Particle dimensions and size distributions using appropriate analytical techniques.
- Particle shape, morphology and aggregation state.
- Detailed optical absorption and scattering spectra.
- Plasmonic behaviour associated with suitably characterised nanoscale gold particles.
- Particle structure and morphology using electron microscopy and related imaging techniques.
WHY THE WORK MATTERS
From Finely Divided Gold to Modern Nanoscience
Faraday's experiments demonstrated that finely divided gold could display optical behaviour very different from bulk metallic gold. Although he could not directly resolve the suspended particles, he could investigate their presence and physical state through observable changes in colour and light.
Scale Changes Behaviour
Gold divided into very small particles can interact with its surroundings and with visible light differently from bulk metallic gold.
Optical Behaviour Reveals Structure
Colour, transmitted light and scattered light gave Faraday experimental evidence about finely divided matter that he could not directly resolve.
A Historical Link to Nanoscience
Faraday's gold experiments became an important historical reference in the later scientific study of colloids, small particles and their optical properties.
PRESERVED SINCE 1856
Faraday's Gold Colloids Are Still Optically Active
Historic gold colloids made during Faraday's work in 1856 are still preserved in the Royal Institution collection, providing a direct physical link to his nineteenth-century experiments.
Remarkably, the preserved colloids remain optically active. Light passed through the liquid can still produce a visible cone of scattered light, reproducing the optical effect Faraday recorded during his original investigations.
Their longevity is scientifically unusual. Colloidal particles can aggregate, settle or change over time, yet these historic preparations have persisted for well over a century. The Royal Institution notes that the precise reason for this exceptional persistence is not known because opening the sealed bottles would damage the historic samples.
1856 Preparations
The preserved gold colloids date from Faraday's experimental work at the Royal Institution in 1856.
Royal Institution Collection
The historic samples remain part of the Royal Institution's scientific collection.
Still Optically Active
A beam of light can still produce the visible scattering effect associated with Faraday's original observations.
Unusual Longevity
Their persistence is scientifically noteworthy, although the exact reason they have remained this way is not established.
THE SCIENTIFIC TIMELINE
From "Divided Gold" to Modern Nanoscience
Faraday investigated optical behaviour in finely divided gold long before scientists could directly characterise particles at nanoscale dimensions. Later advances in microscopy, spectroscopy and materials analysis made it possible to study such particles and their optical properties in much greater detail.
1856 TO 1857
Faraday Investigates Finely Divided Gold
Faraday prepared and studied finely divided gold during the mid-1850s. His 1857 Bakerian Lecture documented experiments on the relationship between gold, other metals and light.
20TH CENTURY
New Instruments Reveal Smaller Scales
Advances in electron microscopy, spectroscopy and other analytical methods gave scientists new ways to image and characterise structures far below the resolving power of nineteenth-century optical instruments.
MODERN RESEARCH
Gold Nanoparticles Become a Research Material
Carefully characterised gold nanoparticles are now investigated across materials science, optics, sensing, electronics and biomedical research. Modern studies can examine defined particle sizes, shapes, surfaces and optical properties.
EXPLORE & REFERENCES
Explore the Historical Sources Behind Faraday's Gold Experiments
Faraday's experiments with finely divided gold are documented in nineteenth-century scientific records, while historic samples from his work remain preserved within the Royal Institution collection.
The Royal Institution
Explore the Royal Institution's collection of Michael Faraday's historic gold colloids, including preparations dating from his experimental work in 1856.
Explore the CollectionExperimental Relations of Gold (and Other Metals) to Light
Explore the Royal Society archive record for Faraday's Bakerian Lecture, received in 1856, read in February 1857 and published in Philosophical Transactions in 1857.
View the Royal Society RecordDiscover More About Colloidal Gold
Continue through Gold Healing's educational guides to explore colloidal dispersions, optical behaviour and modern production.
SCIENCE GUIDE
What Is Colloidal Gold?
Explore elemental gold particles, colloidal dispersions, optical behaviour and the distinction between particulate and ionic gold.
MODERN PRODUCTIONHow Colloidal Gold Is Made
See how Gold Healing describes its modern electrochemical production process using high-purity source gold and distilled water.
GOLD HEALINGColloidal Gold 60ppm
Explore Gold Healing's 500ml liquid preparation made with 24K, 99.99% pure elemental source gold and distilled water.
References & Scientific Context
- Royal Institution. Michael Faraday's Gold Colloids. Collection record documenting Faraday's historic gold colloids, their 1856 date and their continuing optical activity.
- Faraday, M. The Bakerian Lecture. Experimental Relations of Gold (and Other Metals) to Light. Philosophical Transactions of the Royal Society of London, 1857. DOI: 10.1098/rstl.1857.0011.
- Link, S. and El-Sayed, M. A. Size and Temperature Dependence of the Plasmon Absorption of Colloidal Gold Nanoparticles. The Journal of Physical Chemistry B, 1999, 103(21), 4212-4217. DOI: 10.1021/jp984796o.
- Ghosh, S. K. and Pal, T. Interparticle Coupling Effect on the Surface Plasmon Resonance of Gold Nanoparticles: From Theory to Applications. Chemical Reviews, 2007, 107(11), 4797-4862. DOI: 10.1021/cr0680282.
MICHAEL FARADAY FAQ
Questions About Faraday and Colloidal Gold
A concise guide to the key historical and scientific questions surrounding Michael Faraday's work with finely divided gold.
Did Michael Faraday invent colloidal gold?
Not in the modern manufacturing sense. Faraday was one of the earliest scientists to systematically prepare, document and study metallic gold colloids and their interaction with light.
When did Faraday carry out his gold experiments?
Faraday presented his major work on finely divided gold in 1857 in the Bakerian Lecture, later published in the Philosophical Transactions of the Royal Society.
What did Faraday mean by “divided gold”?
Faraday used the term to describe gold broken into extremely small particles rather than existing as a continuous piece of bulk metal. Today, some of the materials he investigated would be discussed in the language of colloids and nanoparticles.
Why were Faraday's gold preparations ruby red?
Finely divided gold can interact with visible light very differently from bulk metallic gold. Modern science explains this through nanoscale optical behaviour involving electrons at the particle surface.
Could Faraday actually see the gold particles?
No. The particles were below the resolving power of the instruments available to him. He instead studied their presence indirectly through colour, light transmission, scattering and changes between different preparations.
What was important about Faraday's 1857 paper?
It provided a detailed experimental investigation of how finely divided metals, particularly gold, interacted with light. The work became an important historical foundation for later colloid and nanoparticle science.
Do Faraday's original gold colloids still exist?
Historic gold preparations associated with Faraday are preserved in the Royal Institution collection, providing a direct physical link to his nineteenth century experiments.
Why is Michael Faraday associated with nanoscience?
Faraday investigated physical behaviour produced by matter divided to an extremely small scale, long before the terminology and instrumentation of modern nanoscience existed. His work therefore occupies an important place in the early history of nanoscale materials research.
Is Faraday's work evidence that colloidal gold has health benefits?
No. Faraday's work concerned the physical and optical behaviour of finely divided gold. Its historical importance does not demonstrate that colloidal gold treats, prevents or cures medical conditions.
