Melting point

The melting point of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium; the melting point of a substance depends on pressure and is specified at a standard pressure such as 1 atmosphere or 100 kPa. When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point or crystallization point; because of the ability of some substances to supercool, the freezing point is not considered as a characteristic property of a substance. When the "characteristic freezing point" of a substance is determined, in fact the actual methodology is always "the principle of observing the disappearance rather than the formation of ice", that is, the melting point. For most substances and freezing points are equal. For example, the melting point and freezing point of mercury is 234.32 Kelvin. However, certain substances possess differing solid-liquid transition temperatures.

For example, agar melts at 85 °C and solidifies from 31 °C. The melting point of ice at 1 atmosphere of pressure is close to 0 °C. In the presence of nucleating substances, the freezing point of water is not always the same as the melting point. In the absence of nucleators water can exist as a supercooled liquid down to −48.3 °C before freezing. The chemical element with the highest melting point is tungsten, at 3,414 °C; the often-cited carbon does not melt at ambient pressure but sublimes at about 3,726.85 °C. Tantalum hafnium carbide is a refractory compound with a high melting point of 4215 K. Quantum mechanical computer simulations have predicted that the alloy HfN0.38C0.51 will have an higher melting point, which would make it the substance with the highest melting point at ambient pressure, but this is yet to be demonstrated physically. At the other end of the scale, helium does not freeze at all at normal pressure at temperatures arbitrarily close to absolute zero. Many laboratory techniques exist for the determination of melting points.

A Kofler bench is a metal strip with a temperature gradient. Any substance can be placed on a section of the strip, revealing its thermal behaviour at the temperature at that point. Differential scanning calorimetry gives information on melting point together with its enthalpy of fusion. A basic melting point apparatus for the analysis of crystalline solids consists of an oil bath with a transparent window and a simple magnifier. Several grains of a solid are placed in a thin glass tube and immersed in the oil bath; the oil bath is heated and with the aid of the magnifier melting of the individual crystals at a certain temperature can be observed. A metal block might be used instead of an oil bath; some modern instruments have automatic optical detection. The measurement can be made continuously with an operating process. For instance, oil refineries measure the freeze point of diesel fuel "online", meaning that the sample is taken from the process and measured automatically; this allows for more frequent measurements as the sample does not have to be manually collected and taken to a remote laboratory.

For refractory materials the high melting point may be determined by heating the material in a black body furnace and measuring the black-body temperature with an optical pyrometer. For the highest melting materials, this may require extrapolation by several hundred degrees; the spectral radiance from an incandescent body is known to be a function of its temperature. An optical pyrometer matches the radiance of a body under study to the radiance of a source, calibrated as a function of temperature. In this way, the measurement of the absolute magnitude of the intensity of radiation is unnecessary. However, known temperatures must be used to determine the calibration of the pyrometer. For temperatures above the calibration range of the source, an extrapolation technique must be employed; this extrapolation is accomplished by using Planck's law of radiation. The constants in this equation are not known with sufficient accuracy, causing errors in the extrapolation to become larger at higher temperatures.

However, standard techniques have been developed to perform this extrapolation. Consider the case of using gold as the source. In this technique, the current through the filament of the pyrometer is adjusted until the light intensity of the filament matches that of a black-body at the melting point of gold; this establishes the primary calibration temperature and can be expressed in terms of current through the pyrometer lamp. With the same current setting, the pyrometer is sighted on another black-body at a higher temperature. An absorbing medium of known transmission is inserted between this black-body; the temperature of the black-body is adjusted until a match exists between its intensity and that of the pyrometer filament. The true higher temperature of the black-body is determined fr

Leslie Ayres

Leslie F. Ayres was an American architect active in Indianapolis, Indiana from 1926 to 1945. Leslie F. Ayres was a well known artist in Indianapolis, Indiana, he was known within the architectural circles for his refined and exquisite renderings. Ayres began his career early with the firm of Wright. During his time with the firm he was awarded the Princeton Prize in Architecture in 1926, which allowed him to attend Princeton University, earn his certificate of proficiency in 1927. Upon his graduation from Princeton, he moved back to Indianapolis, started his own firm, his renderings done in watercolor and colored pencil were used to sell the client on a project, in 1948 National Architect stated he was “just about the only professional renderer in Indiana. Ayres was born in 1906 in Indiana to Frank and Bertha Wolf Ayres; the Ayres had a younger son named Robert. The two brothers both attended Arsenal Technical High School where Leslie learned to draw and developed a passion for architecture. In 1937, Ayres married Edna C.

Silcox. The two were together until he died of a heart attack in 1952 at the age of 46, they had no children. He is buried in Indianapolis, in the Washington Park East Cemetery Leslie F. Ayres was recruited out of high school, by a young Indianapolis architect by the name of Edward Pierre. Pierre recognized his talent for rendering, in 1925 he gave Ayres a job in his newly formed company, Pierre & Wright He would become Ayres’ mentor, Ayres stayed with the company until 1926, when he received the prestigious Princeton Prize in architecture; the award allowed him to attend Princeton University for one year for free tuition. During his time at Princeton, professors lauded him for his natural drawing ability, but his performance was somewhat lackluster, professors complained about his lack of focus on assignments. Despite his difficulties during his year there, Ayres earned his Certificate of Proficiency in 1927, returned to Indianapolis. Upon his return to Indianapolis, Leslie Ayres began working as an architect and renderer in the area.

He received work from his former employers, Pierre & Wright, as well as other prominent Indianapolis architectural firms such as Rubush & Hunter, A. M. Strauss, Robert Frost Daggett, his renderings were popular made in watercolor and colored pencil. His early drawings depict a wide variety of subjects including: power plants, high schools, clubs, civic structures, religious buildings, his professional drawings in the 1930s and 1940s depicted residences, apartment buildings, churches. During a visit to the Chicago World’s Fair in 1933, Ayres sketched scenes from Belgian Village. In 1948, National Architect magazine described him as “just about the only professional renderer in Indiana.” His most celebrated work was the design for the Wilkinson House in Muncie, which he did in the early 1930s. An Art Moderne masterpiece, the house was, still is, celebrated as one of the best examples of this style of residential architecture in Indiana. Ayres was an active leader in the Indianapolis Home Show between 1940 and 1947.

He designed many of the model homes used in the show during this time. His focus was on small sophisticated homes. Depew Memorial Fountain, University Park, Indianapolis, IN, En-Ar-Co and White Rose Service Stations, c. 1930s Columbia Club Sketch, Monument Circle, Indianapolis, IN, c.1930s Polar Ice and Fuel Company, Indianapolis, IN, 1927 Wilkinson House, 3100 West University Avenue, Muncie, IN, c. 1933

Certainty in English law

Certainty in English law sets out rules for how judges will interpret, sever or put contracts and other voluntary obligations into effect. If the terms of the contract are uncertain or incomplete, the parties cannot have reached an agreement in the eyes of the law. An agreement to agree does not constitute a contract, an inability to agree on key issues, which may include such things as price or safety, may cause the entire contract to fail. However, a court will attempt to give effect to commercial contracts where possible, by construing a reasonable construction of the contract. Courts may look to external standards, which are either mentioned explicitly in the contract or implied by common practice in a certain field. In addition, the court may imply a term. If there are uncertain or incomplete clauses in the contract, all options in resolving its true meaning have failed, it may be possible to sever and void just those affected clauses if the contract includes a severability clause; the test of whether a clause is severable is an objective test—whether a reasonable person would see the contract standing without the clause.

While agreement is the basis for all contracts, not all agreements are enforceable. A preliminary question is whether the contract is reasonably certain in its essential terms, such as price, subject matter and the identity of the parties; the courts endeavour to "make the agreement work", so in Hillas & Co Ltd v Arcos Ltd, the House of Lords held that an option to buy softwood of "fair specification" was sufficiently certain to be enforced, when read in the context of previous agreements between the parties. However the courts do not wish to "make contracts for people", so in Scammell and Nephew Ltd v Ouston, a clause stipulating the price of buying a new van as "on hire purchase terms" for two years was held unenforceable because there was no objective standard by which the court could know what price was intended or what a reasonable price might be. In Baird Textile Holdings Ltd v M&S plc the Court of Appeal held that because the price and quantity to buy would be uncertain, in part, no term could be implied for M&S to give reasonable notice before terminating its purchasing agreement.

Controversially, the House of Lords extended this idea by holding an agreement to negotiate towards a future contract in good faith is insufficiently certain to be enforceable. Mercantile Credits Ltd v Harry 2 NSWR 248, failure to specify subject matters Sale of Goods Act 1979, s 8, 9, certainty of terms Brown v Gould Ch 53 Sudbrook Trading Estate Ltd v Eggleton 1 AC 444 Nicolene Ltd v Simmons 1QB 543 May & Butcher v The King 2 KB 17, agreement to agree Foley v Classique Coaches Ltd 2 KB 1 Walford v Miles 2 AC 128, agreement to negotiate Pitt v PHH Asset Management Ltd 1 WLR 327 Branca v Cobarro KB 854, agreement “Subject to Contract” Masters v Cameron 91 CLR 353 Carlton Communications and Granada Media plc v The Football League EWHC 1650 Jones v Lock 1 Ch App 25 Paul v Constance 1 WLR 527 Hunter v Moss 1 WLR 452 Re Barlow’s Will Trusts 1 WLR 278 McPhail v Doulton AC 424 Re Baden’s Deed Trusts Ch 9 Re Tuck’s Settlement Trusts Ch 49 English tort law Contra proferentem Attorney-General v Barker Bros Ltd 2 NZLR 495.

Electricity Corporation of New Zealand v Fletcher Challenge Energy Ltd NZLR