The Color, Blue
February 9, 2015
Because of my Italian ancestry, my veins are not that visible beneath my dark skin. However, fair-skinned people have visible veins, and that's apparently where we get the term, "blue blood," to denote aristocracy. Today, however, the skin of the average one-percenter has become somewhat darker, so "blue-blood" is destined to become an archaic term.
The color, blue, is used to signify a melancholy mood, and the word appears often in popular culture. The following is a list of a few popular songs with blue in their titles. I selected ones that are most familiar to me, and I played many of these in my short, pre-scientific, career as a top-40 DJ.
One look through a window will confirm that half our visible world is blue, at least on the nicer days. Artists and artisans have added blue to their palette through the use of several natural pigments. The most historically famous of these is ultramarine (Na8-10Al6Si6O24S2-4), first obtained by grinding the mineral, lapis lazuli. Lapis lazuli was imported into Renaissance Europe from Afghanistan, so ultramarine was expensive until its chemical synthesis in 1826.
Azurite, another blue pigment, is chemically Cu3(CO3)2(OH)2. Azurite has been known since antiquity, and it's mentioned in Pliny the Elder's Natural History. Our word, "cyan," comes from the Greek word for azurite, κυανος (kyanos). I've often mentioned Pliny's Natural History.
Egyptian blue is calcium copper silicate (CaCuSi4O10). Unlike both ultramarine and azurite, it doesn't exist as a mineral. This first synthetically-produced pigment, known by the Latin name, caeruleum, was produced in Egypt, circa 2500 B.C. It's formed by the high temperature reaction of malachite (copper carbonate hydroxide, Cu2CO3(OH)2), quartz (SiO2), and calcite (CaCO3); viz.,
Cu2CO3(OH)2 + 8SiO2 + CaCO3 -> CaCuSi4O10 + 3CO2 + H2O
Often, a small quantity of sodium carbonate was added to aid in the fusion of the reactants.
As its chemical formula indicates, Prussian blue, Fe7(CN)18, is an inexpensive blue pigment. This chemical was the blue in the now rare blueprints (cyanotypes), and it was also one chemical used in laundry bluing before the current era of optical brighteners (a.k.a., whiteners). Prussian blue is widely used in dyeing, and in the manufacture of inks and other artist's colorants.
One chemical stocked in my childhood chemistry set was cobalt (II) chloride (CoCl2·6H2O). Today, this chemical would not be sold to children, since it's an allergen, but it has a blue color in its anhydrous form. The transition between its hydrous (red) and anhydrous (blue) forms allowed its use as an inexpensive humidity indicator. This one example illustrates the possibility that other cobalt (II) compounds would have a blue color.
And Lo! (I must be channeling Pliny the Elder, here), there are Cobalt blue, which is cobalt(II) aluminate, CoAl2O4, and also Cerulean blue, which is cobalt(II) stannate, Co2SnO4.
Han blue, BaCuSi4O10, also called, Chinese blue, was used in China from about 1000 B.C. Han blue was only discovered in a mineral form, effenbergerite, in 1993. It has always been synthesized from chemical reactants; for example, a fusion of malachite ( copper carbonate hydroxide, quartz), and barium carbonate.
Cu2CO3(OH)2 + 8SiO2 + 2BaCO3 -> 2BaCuSi4O10 + 3CO2 + H2O
You can see that this is the barium analog of the Egyptian blue reaction, using barium carbonate instead of calcium carbonate.
Marc Walton, a senior scientist at the Northwestern University, Art Institute of Chicago, Center for Scientific Studies in the Arts, has been intrigued by blue pigments for the past fifteen years. It started when Walton, as a graduate student, found that the word, "blue," didn't appear until centuries after the first blue pigment, Egyptian blue, appeared. Blue has a special place in pigments, since the color appears often in nature, but it doesn't appear that often in minerals.
The Egyptians made extensive use of blue, but Roman art used very little blue; so, the art of manufacturing blue pigment was lost. Around the 6th century A.D., only lapis lazuli was used as a blue pigment, but it was used sparingly because of its cost. Azurite became a cheaper blue pigment, and it was generally used as a foundation layer for the more vibrant lapis lazuli pigment. In modern times, Prussian blue was used by Picasso, and synthetic chemistry has given us many blue pigment alternatives.
- Megan Fellman, "Who Knew There Was so Much to Blue? - Scientist studies blue's invention and reinvention throughout history," Northwestern University Press Release, November 5, 2014.
- The Natural History of Pliny, John Bostock and H.T. Riley, Trans., (H. G. Bohn: New York, 1857), vol. 6, chap. 57 (via Google Books).
Permanent Link to this article
Linked Keywords: Italy; Italian; ancestor; ancestry; vein; skin; nobility; aristocracy; one-percenter; archaic; blue; depression; melancholy mood; popular culture; song; science; scientific; career; top-40 DJ; Tony Bennett; Blue Velvet; David Bowie; Blue Jean; Neil Diamond; Song Sung Blue; The Doors; Roadhouse Blues; Bob Dylan; Subterranean Homesick Blues; Tangled Up In Blue; Johnny Cash; Folsom Prison Blues; Crosby, Stills, & Nash; Suite: Judy Blue Eyes; Fats Domino; My Blue Heaven; Foreigner; Blue Morning, Blue Day; Tommy James and the Shondells; Crystal Blue Persuasion; The Marcels; Blue Moon; Roy Orbison; Blue Bayou; Carl Perkins; Blue Suede Shoes; Elvis Presley; Linda Rondstat; Bobby Vinton; Blue Velvet; The Who; Behind Blue Eyes; window; artist; artisan; palette; natural pigment; history; historical; ultramarine; grinding; mineral; lapis lazuli; Renaissance Europe; Afghanistan; chemical synthesis; Azurite; copper; carbonate; CO3; hydroxide; OH; Pliny the Elder; Natural History; cyan; Greek language; Melbourne Museum; Graeme Churchard; Wikimedia Commons; Egyptian blue; silicate; calcium; Ca; Silicon; Si; Oxygen; O; Latin; Egypt; Anno Domini; B.C.; temperature; chemical reaction; malachite; quartz; calcite; sodium carbonate; melting; fusion; reagent; reactant; laboratory; chemical synthesis; chemical formula; Prussian blue; blueprint; cyanotype; laundry bluing; optical brightener; dyeing; manufacturing; manufacture; ink; Mrs. Stewart's Bluing; experiment; mother; 1960s; Joe Mabel; childhood; chemistry set; cobalt (II) chloride; cobalt; Co; chlorine; Cl; water; H2O; child; children; allergen; anhydrous; hydrate; hydrous; humidity indicator; chemical compound; Cobalt blue; Cerulean blue; dish; Qing dynasty; Kangxi period (1661-1722); Han blue; barium; Ba; Chinese; China; barium carbonate; analogy; analog; Marc Walton; Northwestern University; Art Institute of Chicago; Center for Scientific Studies in the Arts; graduate student; century; Roman Empire; 6th century A.D.; Pablo Picasso; synthetic chemistry.
Latest Books by Dev Gualtieri
Thanks to Cory Doctorow of BoingBoing for his favorable review of Secret Codes!
Blog Article Directory on a Single Page
- Soybean Graphene - March 23, 2017
- Income Inequality and Geometrical Frustration - March 20, 2017
- Wireless Power - March 16, 2017
- Trilobite Sex - March 13, 2017
- Freezing, Outside-In - March 9, 2017
- Ammonia Synthesis - March 6, 2017
- High Altitude Radiation - March 2, 2017
- C.N. Yang - February 27, 2017
- VOC Detection with Nanocrystals - February 23, 2017
- Molecular Fountains - February 20, 2017
- Jet Lag - February 16, 2017
- Highly Flexible Conductors - February 13, 2017
- Graphene Friction - February 9, 2017
- Dynamic Range - February 6, 2017
- Robert Boyle's To-Do List for Science - February 2, 2017
- Nanowire Ink - January 30, 2017
- Random Triangles - January 26, 2017
- Torricelli's law - January 23, 2017
- Magnetic Memory - January 19, 2017
- Graphene Putty - January 16, 2017
- Seahorse Genome - January 12, 2017
- Infinite c - January 9, 2017
- 150 Years of Transatlantic Telegraphy - January 5, 2017
- Cold Work on the Nanoscale - January 2, 2017
- Holidays 2016 - December 22, 2016
- Ballistics - December 19, 2016
- Salted Frogs - December 15, 2016
- Negative Thermal Expansion - December 12, 2016
- Verbal Cues and Stereotypes - December 8, 2016
- Capacitance Sensing - December 5, 2016
- Gallium Nitride Tribology - December 1, 2016
- Lunar Origin - November 27, 2016
- Pumpkin Propagation - November 24, 2016
- Math Anxiety - November 21, 2016
- Borophene - November 17, 2016
- Forced Innovation - November 14, 2016
- Combating Glare - November 10, 2016
- Solar Tilt and Planet Nine - November 7, 2016
- The Proton Size Problem - November 3, 2016
- Coffee Acoustics and Espresso Foam - October 31, 2016
- SnIP - An Inorganic Double Helix - October 27, 2016
- Seymour Papert (1928-2016) - October 24, 2016
- Mapping the Milky Way - October 20, 2016
- Electromagnetic Shielding - October 17, 2016
- The Lunacy of the Cows - October 13, 2016
- Random Coprimes and Pi - October 10, 2016
- James Cronin (1931-2016) - October 6, 2016
- The Ubiquitous Helix - October 3, 2016
- The Five-Second Rule - September 29, 2016
- Resistor Networks - September 26, 2016
- Brown Dwarfs - September 22, 2016
- Intrusion Rheology - September 19, 2016
- Falsifiability - September 15, 2016
- Fifth Force - September 12, 2016
- Renal Crystal Growth - September 8, 2016
- The Normality of Pi - September 5, 2016
- Metering Electrical Power - September 1, 2016
Deep Archive 2006-2008