Prussian T 20 DRG Class 95 DR Class 95.0/1
Number(s):	DRG 95 001–045
Quantity:	45
Manufacturer:	Borsig, Hanomag
Year(s) of manufacture:	1922–1924
Retired:	1978
Axle arrangement:	1'E1' h2t
Type:	Gt 57.19
Gauge:	1,435 mm
Length over buffers:	15,100 mm
Height:	4,550 mm
Overall wheelbase:	11,900 mm
Empty weight:	103.7 t
Service weight:	127.4 t
Adhesive weight:	95.3 t
Axle load:	19.1 t
Top speed:	70 km/h
Indicated Power:	1,192 kW
Driving wheel diameter:	1,400 mm
Leading wheel diameter:	850 mm
Trailing wheel diameter:	850 mm
No. of cylinders:	2
Cylinder bore:	700 mm
Piston stroke:	660 mm
Boiler Overpressure:	14 bar
Grate area:	4.36 m²
Superheater area:	62.50 m²
Evaporative heating area:	200.00 m²
Water capacity:	12.0 m³
Fuel:	4 t coal
Brakes:	Knorr compressed-air brake Riggenbach counter-pressure brake

The German DRG Class 95 was a ten-coupled tank locomotive with a 2-10-2 wheel arrangement, which was procured by the Deutsche Reichsbahn (also referred to later as the Deutsche Reichsbahn-Gesellschaft or DRG) in 1922 for hauling heavy goods trains on steep main lines. Because the development of this class was begun by the Prussian state railways, it was designated as the Prussian Class T 20.

History[link]

The first ten locomotives, built in 1922, were ordered as T 20 Magdeburg 9201–9210 and, because they were at first intended to be grouped into Class 77, were supplied as numbers 77 001 to 77 010. By 1923 they had been renumbered to 95 001–010. A total of 45 locomotives were built by 1924. Their areas of operations included the Sonneberg–Probstzella line, the Spessart ramp, the Franconian Forest Railway, the Geislingen ramp (Geislinger Steige), the Schiefe Ebene and the Rübeland Railway, where they earned their nickname Bergkönigin ('mountain queen').

The locomotives were the most powerful tank engines procured by the DRG. They could haul a train load of 2060 tonnes at a speed of 50 km/h on the flat and could still manage 430 tonnes at 25 km/h on a 25‰ incline. The very high traction load of 95.3 tonnes enabled it to cope with inclines of up to 70‰ without needing a rack and its Riggenbach counter-pressure brake ensured that it could brake even heavy loads on a downhill stretch.

Of the 45 examples owned by the Reichsbahn, the Deutsche Bundesbahn took over 14 that, towards the end, were stationed in Aschaffenburg and used as pusher locomotives on the Spessart ramp. They were retired in 1958. Locomotives had also been stabled in Neuenmarkt-Wirsberg until 1952 for duties on the Schiefe Ebene.

31 locomotives ended up in the East German Deutsche Reichsbahn. Of these, 24 were rebuilt to oil-firing between 1971 and 1973 and ten were given a newly-designed boiler. From 1970 the oil-fired engines were designated as DR Class 95.0 and the unconverted ones as DR Class 95.1. The last locomotives worked the line from Sonneberg toEisfeld and were retired in 1981.

Preserved Locomotives[link]

The following locomotives have been preserved:

• 95 027 restored and operating on the Rübeland Railway (as of 27 Nov 2010)
• 95 009 (photo above left) at Dieringhausen Railway Museum
• 95 028 in the Bochum-Dahlhausen Railway Museum
• 95 016 (ex Kamenz locomotive depot) in the German Steam Locomotive Museum at Neuenmarkt-Wirsberg.
• 95 020 on display at the Technikmuseum Speyer.

At present only 95 027 is operational.

See also[link]

• Prussian state railways
• List of DRG locomotives and railbuses
• List of Prussian locomotives and railbuses

Sources[link]

• Wolfgang Brozeit, Hans Müller, Günter Bölke: Baureihe 95: Der Lebenslauf der "Bergkönigin". transpress Verlagsgesellschaft, Berlin 1990 (1. Aufl.) und 1994 (2. Aufl.), ISBN 3-344-00377-1.
• Harald Vogelsang: Die Fahrzeuge und Anlagen des Eisenbahnmuseums Bochum-Dahlhausen, ISBN 3-921700-99-X

External links[link]

• Bilder der Baureihe 95
• There is a relevant English-language forum at Railways of Germany

v t e Classes of Prussian locomotive Express train locomotives S 1 S 2 S 3 S 4 S 5.1 S 5.2 S 6 S 7 S 8 S 9 (Exp.) S 9 S 10 S 10.1 S 10.2 S 11 Passenger and express train locomotives P 1 P 2 P 3 P 3.1 P 3.2 P 4 P 4.1 P 4.2 P 6 P 7 P 8 P 10 Goods train locomotives G 1 G 2 G 3 G 4.1 G 4.2 G 4.3 G 5.1 G 5.2 G 5.3 G 5.4 G 5.5 G 7.1 G 7.2 G 7.3 G 8 G 8.1 G 8.2 G 8.3 G 9 (Mallet) G 9 G 10 G 12 (C.F.O.A) G 12 G 12.1 Tank locomotives T 0 T 1 T 2 T 2/T 4 T 2.1 T 2/T 3/T 4 T 3 T 4 T 4.1 T 4.2 T 4.3 T 5.1 T 5.2 T 6 T 7 T 8 T 9 Elberfeld T 9 Langenschwalbach T 9.1 T 9.2 T 9.3 T 10 T 11 T 12 T 13 Hagans T 13.1 T 14 T 14.1 T 14 (Exp.) T 15 T 16 (Exp.) T 16 T 16.1 T 18 T 20 T 26 T 28 Narrow gauge locomotives T 31 T 32 T 33 T 34 T 35 T 36 T 37 T 38 T 39 T 40 Electric locomotives to follow Railbuses to follow

T20 T.20, T 20 or T-20 may refer to:

• T20 Medium Tank, a World War II United States tank
• T-20 armored tractor Komsomolets, a World War II Soviet Union Artillery tractor
• Prussian T 20, a 1922 German ten-coupled 2-10-2 tank steam locomotive
• Suzuki T20, a motorcycle
• DSC-T20, a digital camera in the Sony Cyber-shot T series
• Slingsby T.20, an aircraft made by Slingsby Aviation
• T-20, also called Enfuvirtide, an HIV drug.
• Twenty20, a form of cricket
• AT-20, the U.S. Army Air Forces designation for the Avro Anson

This disambiguation page lists articles associated with the same title formed as a letter-number combination. If an internal link led you here, you may wish to change the link to point directly to the intended article.

Prussian blue
IUPAC name Iron(II,III) hexacyanoferrate(II,III)
Other names Berlin blue Ferric ferrocyanide Ferric hexacyanoferrate Iron(III) ferrocyanide Iron(III) hexacyanoferrate(II) Parisian blue
Identifiers
CAS number	14038-43-8 Y
PubChem	2724251
ChemSpider	20074656 Y
UNII	TLE294X33A Y
EC number	237-875-5
ChEBI	CHEBI:30069 Y
ChEMBL	CHEMBL1200325 N
RTECS number	V03AB31
Gmelin Reference	1093743
Jmol-3D images	Image 1
SMILES [Fe+3].[Fe+3].[Fe+3].[Fe+3].N#C[Fe-4](C#N)(C#N)(C#N)(C#N)C#N.N#C[Fe-4](C#N)(C#N)(C#N)(C#N)C#N.N#C[Fe-4](C#N)(C#N)(C#N)(C#N)C#N
InChI InChI=1S/18CN.7Fe/c18*1-2;;;;;;;/q;;;;;;;;;;;;;;;;;;3*-4;4*+3 Y Key: DNMNDNSFJMUUFM-UHFFFAOYSA-N Y InChI=1S/18CN.7Fe/c18*1-2;;;;;;;/q;;;;;;;;;;;;;;;;;;3*-4;4*+3
Properties
Molecular formula	C18Fe7N18
Molar mass	859.23 g mol−1
Appearance	Blue opaque crystals
Pharmacology
Routes of administration	Oral
Hazards
MSDS	MSDS prussian blue
Related compounds
Other cations	Potassium ferrocyanide Sodium ferrocyanide
N (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Prussian Blue
— Color coordinates —
Hex triplet		#003153
RGBB	(r, g, b)	(0, 49, 83)
HSV	(h, s, v)	(205°, 100%, 33%)
Source		[1]
B: Normalized to [0–255] (byte)

Prussian blue is a dark blue pigment with the idealized formula Fe₇(CN)₁₈. Another name for the color Prussian blue is Berlin blue or, in painting, Parisian blue. Turnbull's blue is the same substance but is made from different reagents.

Prussian blue was one of the first synthetic pigments. It is employed as a very fine colloidal dispersion, as the compound itself is not soluble in water. It is famously complex,^[1] owing to the presence of variable amounts of other ions and the sensitive dependence of its appearance on the size of the colloidal particles formed when it is made. The pigment is used in paints, and it is the traditional "blue" in blueprints.

In medicine, Prussian blue is used as an antidote for certain kinds of heavy metal poisoning (caesium and thallium).

Prussian blue lent its name to prussic acid, which was derived from it, and to ferrocyanide (originally meaning "blue compound of iron", from Latin ferrum and Greek κυανεος). As ferrocyanide is made of iron and CN ligands, reinterpreting the component "-cyanide" in the compound word, produced the word "cyanide" for compounds containing the CN radical.

History[link]

Prussian blue [Fe₄[Fe(CN)₆]₃] was probably synthesized for the first time by the paint maker Diesbach in Berlin around the year 1706.^[2] Most historical sources do not mention a first name of Diesbach. Only Berger refers to him as Johann Jacob Diesbach.^[3] It was named "Preußisch blau" and "Berlinisch Blau" in 1709 by its first trader.^[4] The pigment replaced the expensive Lapis lazuli and was an important topic in the letters exchanged between Johann Leonhard Frisch^[5] and the president of the Royal Academy of Sciences, Gottfried Wilhelm Leibniz, between 1708 and 1716.^[4] It is first mentioned in a letter written by Frisch to Leibniz, from March 31, 1708. Not later than 1708, Frisch began to promote and sell the pigment across Europe. By August 1709, the pigment had been termed "Preussisch blau"; by November 1709, the German name "Berlinisch Blau" had been used for the first time by Frisch. Frisch himself is the author of the first known publication of Prussian blue in the paper Notitia Coerulei Berolinensis nuper inventi in 1710, as can be deduced from his letters. Diesbach had been working for Frisch since about 1701.

In 1731, Georg Ernst Stahl published an account of the first synthesis of Prussian blue.^[6] The story involves not only Diesbach but also Johann Konrad Dippel. Diesbach was attempting to create a red lake pigment from cochineal but obtained the blue instead as a result of the contaminated potash he was using. He borrowed the potash from Dippel, who had used it to produce his "animal oil". No other known historical source mentions Dippel in this context. It is therefore difficult to judge the reliability of this story today. In 1724, the recipe was finally published by John Woodward.^[7][8][9]

To date, the "Entombment of Christ", dated 1709 by Pieter van der Werff (Picture Gallery, Sanssouci, Potsdam) is the oldest known painting where Prussian blue was used. Around 1710, painters at the Prussian court were already using the pigment. At around the same time, Prussian blue arrived in Paris, where Antoine Watteau and later his successors Nicolas Lancret and Jean-Baptiste Pater used it in their paintings.^[10]

"The Great Wave off Kanagawa" by Hokusai, a famous artwork which makes extensive use of Prussian blue.

This Prussian blue pigment is significant since it was the first stable and relatively lightfast blue pigment to be widely used following the loss of knowledge regarding the synthesis of Egyptian Blue. European painters had previously used a number of pigments such as indigo dye, smalt, and Tyrian purple, which tend to fade, and the extremely expensive ultramarine made from lapis lazuli. Japanese painters and woodblock print artists likewise did not have access to a long-lasting blue pigment until they began to import Prussian blue from Europe.

In 1752 the French chemist Pierre J. Macquer made the important step of showing the Prussian blue could be reduced to a salt of iron and a new acid, which could be used to reconstitute the dye.^[11] The new acid, hydrogen cyanide, first isolated from Prussian blue in pure form and characterized about 1783 by the Swedish chemist Carl Wilhelm Scheele, was eventually given the name Blausäure (literally "Blue acid") because of its derivation from Prussian blue, and in English became known popularly as Prussic acid. Prussian blue would also give the name to the ferrocyanide and cyanide family of compounds. Ferrocyanide (which is yellow) was coined as Neo Latin for "iron-containing blue material", since it was first isolated from Prussian blue. Cyanide, a colorless anion that forms in the process of making Prussian Blue, was named, in turn, for hydrogen cyanide (also colorless), and ultimately from ferrocyanide. It is for this reason that cyanide, even though the name of a colorless radical, is a Latinized form of the Greek word for "dark blue."

Production[link]

Prussian blue is produced by oxidation of ferrous ferrocyanide salts. These white solids have the formula M₂Fe[Fe(CN)₆] where M⁺ = Na⁺ or K⁺. The iron in this material is all ferrous, hence the absence of deep color associated with the mixed valency. Oxidation of this white solid with hydrogen peroxide or sodium chlorate produces ferricyanide and affords Prussian Blue.^[12]

A "soluble" form of PB, K[Fe^IIIFe^II(CN)₆], which is really colloidal, can be made from potassium ferrocyanide and iron(III):

K⁺ + Fe³⁺ + [Fe^II(CN)₆]^4- → KFe^III[Fe^II(CN)₆]

The similar reaction of potassium ferricyanide and iron(II) results in the same colloidal solution, because [Fe^III(CN)₆]^3- is converted into ferrocyanide.

"Insoluble" Prussian blue is produced if in the reactions above an excess of Fe³⁺ or Fe²⁺, respectively, is added.  In the first case:

4Fe³⁺ + 3[Fe^II(CN)₆]^4- → Fe^III[Fe^IIIFe^II(CN)₆]₃ ^[13]

"Turnbull's blue"[link]

Ferricyanide ion, used to make 'Turnbull's blue'.

In former times, it was thought that addition of Fe(II) salts to a solution of ferricyanide affords a material different from Prussian blue. The product was traditionally named "Turnbull's Blue" (TB). It has been shown, however, by means of X-ray diffraction and electron diffraction methods, that the structures of PB and TB are identical.^[14][15] The differences in the colors for TB and PB reflect subtle differences in the method of precipitation, which strongly affects particle size and impurity content.

Properties[link]

Prussian blue is a microcrystalline blue powder. It is insoluble, but the crystallites tend to form a colloid. Such colloids can pass through fine filters.^[1] Despite being one of the oldest known synthetic compounds, the composition of Prussian blue remained uncertain for many years. The precise identification of Prussian blue was complicated by three factors:

1. Prussian blue is extremely insoluble but also tends to form colloids;
2. Traditional syntheses tend to afford impure compositions;
3. Even pure Prussian blue is structurally complex, defying routine crystallographic analysis.

Crystal structure[link]

The chemical formula of insoluble Prussian blue is Fe₇(CN)₁₈·xH₂O, where x = 14–16. The structure was determined by using IR spectroscopy, Moessbauer spectroscopy, X-ray crystallography, and neutron crystallography. Since X-ray diffraction cannot distinguish carbon from nitrogen, the location of these lighter elements is deduced by spectroscopic means as well as by observing the distances from the iron atom centers.

PB has a cubic lattice structure. Soluble PB crystals contain interstitial K⁺ ions; insoluble PB has interstitial water instead.
In ideal insoluble PB crystals, the cubic framework is built from Fe(II)-C-N-Fe(III) sequences, with Fe(II)-carbon distances of 1.92 Å and Fe(III)-nitrogen distances of 2.03 Å. One-fourth of the sites of Fe(CN)₆ subunits are vacant (empty), leaving three such groups. The empty nitrogen sites are filled with water molecules instead, which are coordinated to Fe(III).

The Fe(II) centers, which are low spin, are surrounded by six carbon ligands in an octahedral configuration. The Fe(III) centers, which are high spin, are octahedrally surrounded on average by 4.5 nitrogen atoms and 1.5 oxygen atoms (the oxygen from the six coordinated water molecules). Additional eight (interstitial) water molecules are present in the unit cell, either as isolated molecules or hydrogen bonded to the coordinated water.

The composition is notoriously variable due to the presence of lattice defects, allowing it to be hydrated to various degrees as water molecules are incorporated into the structure to occupy cation vacancies. The variability of Prussian blue's composition is attributable to its low solubility, which leads to its rapid precipitation without the time to achieve full equilibrium between solid and liquid.^{[16] [17]}

Color[link]

Prussian blue is strongly colored and tends towards black and dark blue when mixed into oil paints. The exact hue depends on the method of preparation, which dictates the particle size. The intense blue color of Prussian blue is associated with the energy of the transfer of electrons from Fe(II) to Fe(III). Many such mixed-valence compounds absorb certain wavelengths of visible light resulting from intervalence charge transfer. In this case, orange-red light around 680 nanometers in wavelength is absorbed, and the reflected light appears blue as a result.

Like most high chroma pigments, Prussian blue cannot be accurately displayed on a computer display, but this swatch gives a common approximation, the sRGB colour #003153, intended for viewing on an output device with a gamma of 2.2^[18]:

_________

PB is electrochromic—changing from blue to colorless upon reduction. This change is caused by reduction of the Fe(III) to Fe(II) eliminating the intervalence charge transfer that causes Prussian blue's color.

Uses[link]

Pigment[link]

Because it is easily made, cheap, non-toxic, and intensely colored, Prussian blue has attracted many applications. The dominant uses are for pigments: approximately 12,000 tonnes of Prussian blue are produced annually for use in black and bluish inks. A variety of other pigments also contain the material.^[12] Engineer's blue and the pigment formed on cyanotypes—giving them their common name blueprints. Certain crayons were once colored with Prussian blue (later relabeled Midnight Blue). It is also a popular pigment in paints. Similarly, Prussian blue is the basis for laundry bluing.

Medicine[link]

Prussian blue's ability to incorporate monocations makes it useful as a sequestering agent for certain heavy metal poisons. Pharmaceutical-grade Prussian blue in particular is used for patients who have ingested thallium or radioactive caesium. According to the International Atomic Energy Agency, an adult male can eat at least 10 grams of Prussian blue per day without serious harm. The U.S. Food and Drug Administration (FDA) has determined that the "500 mg Prussian blue capsules, when manufactured under the conditions of an approved New Drug Application (NDA), can be found safe and effective therapy" in certain poisoning cases.^[19] Radiogardase (Prussian blue in soluble capsules ^[20]) is a commercial product for the removal of caesium-137 from the intestine and so indirectly from the bloodstream by intervening in the enterohepatic circulation of caesium-137,^[21] reducing the internal residency time (and exposure) by about two-thirds.

Laboratory histopathology stain for iron[link]

Prussian blue stain

Prussian blue is a common histopathology stain used by pathologists to detect the presence of iron in biopsy specimens, such as in bone marrow samples. The original stain formula, known historically (1867) as "Perls' Prussian blue" after its inventor, German pathologist Max Perls (1843–1881), used separate solutions of potassium ferrocyanide and acid to stain tissue (these are now used combined, just before staining). Iron deposits in tissue then form the purple Prussian blue dye in place, and are visualized as blue or purple deposits.^[22] The formula is also known as Perls Prussian blue and (incorrectly) as Perl's Prussian blue.

By machinists and toolmakers[link]

Prussian blue in oil paint is the traditional material used for spotting metal surfaces such as surface plates and bearings for hand scraping. A thin layer of non-drying paste is applied to a reference surface and transfers to the high spots of the workpiece. The toolmaker then scrapes, stones, or otherwise removes the marked high spots. Prussian blue is preferable because it will not abrade the extremely precise reference surfaces as many ground pigments may.

Analytical chemistry[link]

Prussian blue is formed in the Prussian blue assay for total phenols. Samples and phenolic standards are given acidic ferric chloride and ferricyanide which is reduced to ferrocyanide by the phenols. The ferric chloride and ferrocyanide react to form Prussian blue. Comparing the absorbance at 700 nm of the samples to the standards allows for the determination of total phenols.^[23]

Safety[link]

Despite the fact that it is prepared from cyanide salts, Prussian blue is nontoxic because the cyanide groups are tightly bound to Fe. Other polymeric cyanometalates are similarly stable with low toxicity.^{[citation needed]}

See also[link]

References[link]

External links[link]

• The FDA's page on prussian blue
• The CDC's page on prussian blue
• National Pollutant Inventory – Cyanide compounds fact sheet
• Heyltex Corporation distributors of Radiogardase (Prussian blue insoluble capsules)
• Sarah Lowengard, "Prussian Blue" in The Creation of Color in Eighteenth Century Europe Columbia University Press, 2006

Thomas Kuntz is an American multi-media artist notable for his contemporary automata. He has devoted a lifetime to acquiring the skills of a designer, sculptor, mechanic, automatist, animator, model-maker, painter and conceptualist.^[1]

Early life[link]

Kuntz was born in Phoenix, Arizona January 13, 1965. The youngest of four, his father was a surgeon, and his mother a folk artist/doll maker. They both provided the necessary gene pool and a stimulating environment for him to grow.^[2] As a child he poured over anatomy books, sketchpads, and built his first scale model at age six. As a model maker, he was competing in the masters class (professional) by age 16. Kuntz spent the balance of his youth playing soccer, ending in a brief stint with the Western Soccer League (WSL).

Early Works[link]

In 1986, Thomas began a professional sculpting career with his own experimental entity called Artomic Creations. While contemporaries focused on popular characters, Thomas became one of the pioneers of the garage kit industry by creating several figure models based on obscure characters from silent movies and occult lore.^[3] Gaining notoriety upon these works, he was courted by commercial model and toy companies such as Screamin‘ Products Bowen Designs, Mattel, Ertl Company and Jakks Pacific.^[4] Subsequent inspiration came from the legendary Maila Nurmi (Vampira). They met in 1990 when Thomas was granted permission to model a Vampira figure, and they remained confidants for 18 years until the day when he was a pallbearer at her funeral.^[5] To quote Kuntz in an article he wrote shortly after her death, “She was a mentor, a muse, and a huge inspiration to me.” ^[6]

Current Works[link]

Kuntz now works full-time as a multi-media artist, focusing on automatons, moving sculptures and machines. The British illusionist, Simon Drake noted "Thomas's projects tend to feature the mysterious, uncanny, sometimes darkly horrific and bittersweet sad aspects of human nature. It is not uncommon to see his projects packaged with a strong dose of 'gallows humor', theatrics and magic." ^[7] Thomas uses uncanny valley, the theory holds that when robots and other facsimiles of humans look and act almost like actual humans, it causes a response of revulsion among human observers. The "valley" in question is a dip in a proposed graph of the positivity of human reaction as a function of a robot's life-likeness. In robotics this is seen as a problem. Kuntz uses this as an area of exploration.

On his most complex piece to date, the “Alchemyst’s Clock Tower” uses theme park technology and 18th century automaton techniques applied to fine art. The clock tower is a 9 ft tall miniature theater with a 12” tall magician that conjures fire demons, turns pillars into water, produces optical illusions, and interacts with the audience.^[8] “L’Oracle“, his fortune telling automaton appeared on a Halloween special of the Martha Stewart television show as part of Richard Garriott’s collection.^[9]

Other notable works include animatronics and stage design for the industrial band Skinny Puppy's Doomsday: Back and Forth Series 5: Live in Dresden, and various live shows for Ohgr. Kuntz was also the animator, art director and stop-motion puppet builder for Ohgr's music video Majik, directed by William Morrison. A small collection of his works were borrowed by director William Malone for the film Parasomnia.^[10]

Influences[link]

Kuntz takes an alchemical approach to his art, conjoining seemingly opposing ideas and techniques. Kuntz’s works are influenced equally by low-brow and high-brow sensibilities, ranging from Expressionism, Dada /Surrealism, to the old masters Albrecht Dürer, Hieronymus Bosch, Bruegel, Da Vinci, and Archimboldo. Mechanical influences include 18th and 19th century android makers, particularly Jacques de Vaucanson, Pierre Jaquet-Droz, Jean-Frédéric Leschot, and the great parisian makers of the golden age. Other magical influences include Wolfgang von Kempelen, the French mechanic/magician Robert Houdin, as well as Walt Disney and the early Imagineers; especially Rolly Crump.^[11]

References[link]

External links[link]

• http://thomaskuntz.com
• http://www.artomic.com
• http://www.youtube.com/user/haxanthrobo
• “Majik” http://www.youtube.com/watch?v=QJSsEPSmdMI