Nitrogen is a chemical element with symbol N and atomic number 7. It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772. Although Carl Wilhelm Scheele and Henry Cavendish had independently done so at about the same time, Rutherford is accorded the credit because his work was published first; the name nitrogène was suggested by French chemist Jean-Antoine-Claude Chaptal in 1790, when it was found that nitrogen was present in nitric acid and nitrates. Antoine Lavoisier suggested instead the name azote, from the Greek ἀζωτικός "no life", as it is an asphyxiant gas. Nitrogen is the lightest member of group 15 of the periodic table called the pnictogens; the name comes from the Greek πνίγειν "to choke", directly referencing nitrogen's asphyxiating properties. It is a common element in the universe, estimated at about seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure, two atoms of the element bind to form dinitrogen, a colourless and odorless diatomic gas with the formula N2.
Dinitrogen forms about 78 % of Earth's atmosphere. Nitrogen occurs in all organisms in amino acids, in the nucleic acids and in the energy transfer molecule adenosine triphosphate; the human body contains about 3% nitrogen by mass, the fourth most abundant element in the body after oxygen and hydrogen. The nitrogen cycle describes movement of the element from the air, into the biosphere and organic compounds back into the atmosphere. Many industrially important compounds, such as ammonia, nitric acid, organic nitrates, cyanides, contain nitrogen; the strong triple bond in elemental nitrogen, the second strongest bond in any diatomic molecule after carbon monoxide, dominates nitrogen chemistry. This causes difficulty for both organisms and industry in converting N2 into useful compounds, but at the same time means that burning, exploding, or decomposing nitrogen compounds to form nitrogen gas releases large amounts of useful energy. Synthetically produced ammonia and nitrates are key industrial fertilisers, fertiliser nitrates are key pollutants in the eutrophication of water systems.
Apart from its use in fertilisers and energy-stores, nitrogen is a constituent of organic compounds as diverse as Kevlar used in high-strength fabric and cyanoacrylate used in superglue. Nitrogen is a constituent including antibiotics. Many drugs are mimics or prodrugs of natural nitrogen-containing signal molecules: for example, the organic nitrates nitroglycerin and nitroprusside control blood pressure by metabolizing into nitric oxide. Many notable nitrogen-containing drugs, such as the natural caffeine and morphine or the synthetic amphetamines, act on receptors of animal neurotransmitters. Nitrogen compounds have a long history, ammonium chloride having been known to Herodotus, they were well known by the Middle Ages. Alchemists knew nitric acid as aqua fortis, as well as other nitrogen compounds such as ammonium salts and nitrate salts; the mixture of nitric and hydrochloric acids was known as aqua regia, celebrated for its ability to dissolve gold, the king of metals. The discovery of nitrogen is attributed to the Scottish physician Daniel Rutherford in 1772, who called it noxious air.
Though he did not recognise it as an different chemical substance, he distinguished it from Joseph Black's "fixed air", or carbon dioxide. The fact that there was a component of air that does not support combustion was clear to Rutherford, although he was not aware that it was an element. Nitrogen was studied at about the same time by Carl Wilhelm Scheele, Henry Cavendish, Joseph Priestley, who referred to it as burnt air or phlogisticated air. Nitrogen gas was inert enough that Antoine Lavoisier referred to it as "mephitic air" or azote, from the Greek word άζωτικός, "no life". In an atmosphere of pure nitrogen, animals died and flames were extinguished. Though Lavoisier's name was not accepted in English, since it was pointed out that all gases are mephitic, it is used in many languages and still remains in English in the common names of many nitrogen compounds, such as hydrazine and compounds of the azide ion, it led to the name "pnictogens" for the group headed by nitrogen, from the Greek πνίγειν "to choke".
The English word nitrogen entered the language from the French nitrogène, coined in 1790 by French chemist Jean-Antoine Chaptal, from the French nitre and the French suffix -gène, "producing", from the Greek -γενής. Chaptal's meaning was that nitrogen is the essential part of nitric acid, which in turn was produced from nitre. In earlier times, niter had been confused with Egyptian "natron" – called νίτρον in Greek – which, despite the name, contained no nitrate; the earliest military and agricultural applications of nitrogen compounds used saltpeter, most notably in gunpowder, as fertiliser. In 1910, Lord Rayleigh discovered that an electrical discharge in nitrogen gas produced "active nitrogen", a monatomic allotrope of nitrogen; the "whirling cloud of brilliant yellow light
Plastic milk container
Plastic milk containers are plastic containers for storing and dispensing milk. Plastic bottles, sometimes called jugs, have replaced glass bottles for home consumption. Glass milk bottles have traditionally been reusable while light-weight plastic bottles are designed for single trips and plastic recycling. Packaging of milk is regulated by regional authorities. Use of Food contact materials is required: potential food contamination is prohibited. Strict standards of cleanliness and processing must be followed; the most common material in milk packaging is high density polyethylene, recycling code 2. Low density polyethylene, polyester, are in use. Polycarbonate had been considered but had concerns about potential contamination with Bisphenol A. Blow molded. HDPE is the primary material but polyester is used. A wide variety of milk bottle designs are available; some have a round cross section while others have rectangular shape. A special flat-top square milk jug was developed to maximize shipping and storing efficiency but had some difficulties in dispensing.
Many milk bottles have integral handles. Milk bags are in use; the milk is put into a pitcher for use. Small individual containers of milk and cream are thermoformed or injection molded and have a peelable lid; these are used in restaurants. Many potential factors are involved in environmental comparisons of returnable vs non-returnable systems. Researchers have used life cycle analysis methodologies to balance the many diverse considerations; the comparisons show benefits and problems with all alternatives. Reuse of bottles requires a reverse logistics system, cleaning and, sanitizing bottles, an effective Quality Management System. A key factor with glass milk bottles is the number of cycles of uses to be expected. Breakage, contamination, or other loss reduces the benefits of returnables. A key factor with one-way recyclables is the recycling rate: In the US, only about 30-35% of HDPE bottles are recycled. Yam, K. L. "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009, ISBN 978-0-470-08704-6
The terms active packaging, intelligent packaging, smart packaging refer to packaging systems used with foods and several other types of products. They help extend shelf life, monitor freshness, display information on quality, improve safety, improve convenience; the terms are related. Active packaging means having active functions beyond the inert passive containment and protection of the product. Intelligent and smart packaging involve the ability to sense or measure an attribute of the product, the inner atmosphere of the package, or the shipping environment; this information can trigger active packaging functions. Programmable matter, smart materials, etc can be employed in packages. Depending on the working definitions, some traditional types of packaging might be considered as "active" or "intelligent". More the terms are used with new technologically advanced systems: microelectronics, computer applications, etc. For many years, desiccants have been used to control the water vapor in a closed package.
A desiccant is a hygroscopic substance in a porous pouch or sachet, placed inside a sealed package. They have been used to reduce corrosion of machinery and electronics and to extend the shelf life of moisture sensitive foods and drugs. Corrosion inhibitors can be applied to items to help prevent corrosion. Volatile corrosion inhibitors or vapor phase corrosion inhibitors can be provided inside a package in a pouch or can be incorporated in a saturated overwrap of special paper. Many of these are organic salts; some films have VCI emitting capability. Films are available with copper ions in the polymer structure, These neutralize the corrosive gas in a package and deter rust. VCIs create a neutral environment in the packaging, it works on the principle of difference in vapour pressure and causes reaction with metals and non-metals, with moisture to prevent corrosion. There are different forms of VCIs available, such as papers, plastics, HDPE papers, foams, aluminum barrier foils and emitters that can prevent corrosion at many stages.
Trace transition metals in foods iron, can induce oxidative degradation of many food components lipids, cause quality changes of the products. Metal-chelating active packaging materials are made by immobilizing metal-chelating active compounds onto traditional active packaging material; the surface immobilized metal-chelating compounds can scavenge the transition metals from the product and enhance the oxidative stability of the product. The metal-chelating active packaging technology is antioxidant active packaging that will extend the shelf-life of consumer products by controlling the oxidation; the metal-chelating active packaging technology is known to be able to remove synthetic food preservatives from the food product. This technology can be used to address the increasing consumer demand for additive free and'clean' label food products. Oxygen scavengers or oxygen absorbers help remove oxygen from a closed package; some are small packets or sachets containing powdered iron: as the iron rusts, oxygen is removed from the surrounding atmosphere.
Newer systems can be built into package films or molded structures. In addition, the physical characteristics of the packaging itself can dictate how effective an oxygen absorber can be, how long it will stay effective. Packaging with a low OTR will let less oxygen in the closed package through the polymer barrier itself. With some products, such as cheese, it has long been common to flush the package with nitrogen prior to sealing: the inert nitrogen is absorbed into the cheese, allowing a tight shrink film package; the nitrogen removes oxygen and interacts with the cheese to make the package functional. More other mixtures of gas have been used inside the package to extend the shelf life; the gas mixture depends on its degradation mechanisms. Some package components have been developed that incorporate active chemistry to help maintain certain atmospheres in packages. Oxygen scavengers, carbon dioxide generators, ethanol generators, etc. are available to help keep the atmosphere in a package at specified conditions.
Some temperature indicators give a visual signal. Others, Time temperature indicators, signal when a critical accumulation of temperature deviation over time has been exceeded; when the mechanism of the indicator is tuned to the mechanism of product degradation, these can provide valuable signals for consumers. Digital temperature data loggers record; this data can be used to predict product degradation and help determine if the product is suited for normal sale or if expedited sale is required. They determine the time of the temperature excess: this can be used to direct corrective action. Thermochromic inks are sometimes used to signal temperature change; some are reversible. These can be used alone or with other packaging functions such as barcodes; the inks can signal a desired temperature for consumers. For example, one type of beer can has ink that graphically shows when an ideal drinking temperature is achieved. For critical vaccines, insulated shipping containers are passive packaging to help control the temperatures fluctuations seen with a controlled cold chain.
In addition, gel packs are used to keep the temperature of the contents within specified acceptable temperature ranges. Some newer packages have the ability to heat or cool the product for the
Shelf-stable food is food of a type that can be safely stored at room temperature in a sealed container. This includes foods that would be stored refrigerated but which have been processed so that they can be safely stored at room or ambient temperature for a usefully long shelf life. Various food preservation and packaging techniques are used to extend a food's shelf life. Decreasing the amount of available water in a product, increasing its acidity, or irradiating or otherwise sterilizing the food and sealing it in an air-tight container are all ways of depriving bacteria of suitable conditions in which to thrive. All of these approaches can all extend a food's shelf life without unacceptably changing its taste or texture. For some foods alternative ingredients can be used. Common oils and fats become rancid quickly if not refrigerated; this is a common approach in industrial food production, but recent concerns about health hazards associated with trans fats have led to their strict control in several jurisdictions.
Where trans fats are not prohibited, in many places there are new labeling laws, which require information to be printed on packages, or to be published elsewhere, about the amount of trans fat contained in certain products. Package sterility and seal integrity are vital for commercially packaged shelf-stable food products. With flexible packaging, the choice of materials and process conditions are an important decision for packaging engineers. All aspects of food production, package filling and sealing must be controlled and meet regulatory requirements. Uniformity and other requirements are needed to maintain Good Manufacturing Practices. Product safety management is vital. A complete Quality Management System must be in place. Verification and validation involves collecting documentary evidence of all aspects of compliance. Quality assurance extends beyond the packaging operations through distribution. Commercial canning involves sealing it in sterilized tin cans. Home canning involves mason jars and boiling the containers to kill or weaken any remaining bacteria as a form of sterilization.
Retort pouches involve heat processing the food in sterilized heat-stable flexible packages. This is used for camping food and military field rations The first shelf-stable formulation of ranch dressing, created in 1983, had a shelf life of 150 days. Pasturized milk in aseptically processed cartons is shelf-stable without refrigeration. Fruit juice can be processed with proper pasteurization to allow shelf-stable options. List of dried foods Meal, Ready-to-Eat Retort pouch Hurdle technology
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group on the periodic table, a reactive nonmetal, an oxidizing agent that forms oxides with most elements as well as with other compounds. By mass, oxygen is the third-most abundant element in the universe, after helium. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. Diatomic oxygen gas constitutes 20.8% of the Earth's atmosphere. As compounds including oxides, the element makes up half of the Earth's crust. Dioxygen is used in cellular respiration and many major classes of organic molecules in living organisms contain oxygen, such as proteins, nucleic acids and fats, as do the major constituent inorganic compounds of animal shells and bone. Most of the mass of living organisms is oxygen as a component of water, the major constituent of lifeforms. Oxygen is continuously replenished in Earth's atmosphere by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide.
Oxygen is too chemically reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form of oxygen, ozone absorbs ultraviolet UVB radiation and the high-altitude ozone layer helps protect the biosphere from ultraviolet radiation. However, ozone present at the surface is a byproduct of thus a pollutant. Oxygen was isolated by Michael Sendivogius before 1604, but it is believed that the element was discovered independently by Carl Wilhelm Scheele, in Uppsala, in 1773 or earlier, Joseph Priestley in Wiltshire, in 1774. Priority is given for Priestley because his work was published first. Priestley, called oxygen "dephlogisticated air", did not recognize it as a chemical element; the name oxygen was coined in 1777 by Antoine Lavoisier, who first recognized oxygen as a chemical element and characterized the role it plays in combustion. Common uses of oxygen include production of steel and textiles, brazing and cutting of steels and other metals, rocket propellant, oxygen therapy, life support systems in aircraft, submarines and diving.
One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work Pneumatica, Philo observed that inverting a vessel over a burning candle and surrounding the vessel's neck with water resulted in some water rising into the neck. Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass. Many centuries Leonardo da Vinci built on Philo's work by observing that a portion of air is consumed during combustion and respiration. In the late 17th century, Robert Boyle proved. English chemist John Mayow refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus. In one experiment, he found that placing either a mouse or a lit candle in a closed container over water caused the water to rise and replace one-fourteenth of the air's volume before extinguishing the subjects.
From this he surmised that nitroaereus is consumed in both combustion. Mayow observed that antimony increased in weight when heated, inferred that the nitroaereus must have combined with it, he thought that the lungs separate nitroaereus from air and pass it into the blood and that animal heat and muscle movement result from the reaction of nitroaereus with certain substances in the body. Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract "De respiratione". Robert Hooke, Ole Borch, Mikhail Lomonosov, Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element; this may have been in part due to the prevalence of the philosophy of combustion and corrosion called the phlogiston theory, the favored explanation of those processes. Established in 1667 by the German alchemist J. J. Becher, modified by the chemist Georg Ernst Stahl by 1731, phlogiston theory stated that all combustible materials were made of two parts.
One part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx. Combustible materials that leave little residue, such as wood or coal, were thought to be made of phlogiston. Air did not play a role in phlogiston theory, nor were any initial quantitative experiments conducted to test the idea. Polish alchemist and physician Michael Sendivogius in his work De Lapide Philosophorum Tractatus duodecim e naturae fonte et manuali experientia depromti described a substance contained in air, referring to it as'cibus vitae', this substance is identical with oxygen. Sendivogius, during his experiments performed between 1598 and 1604, properly recognized that the substance is equivalent to the gaseous byproduct released by the thermal decomposition of potassium nitrate. In Bugaj’s view, the isolation of oxygen and the proper association of the substance to that part of air, required for life, lends sufficient weight to the discovery of oxygen by Sendivogius.
Nitrous oxide known as laughing gas or nitrous, is a chemical compound, an oxide of nitrogen with the formula N2O. At room temperature, it is a colourless non-flammable gas, with taste. At elevated temperatures, nitrous oxide is a powerful oxidiser similar to molecular oxygen, it is soluble in water. Nitrous oxide has significant medical uses in surgery and dentistry, for its anaesthetic and pain reducing effects, its name "laughing gas", coined by Humphry Davy, is due to the euphoric effects upon inhaling it, a property that has led to its recreational use as a dissociative anaesthetic. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system, it is used as an oxidiser in rocket propellants, in motor racing to increase the power output of engines. Nitrous oxide occurs in small amounts in the atmosphere, but has been found to be a major scavenger of stratospheric ozone, with an impact comparable to that of CFCs, it is estimated that 30% of the N2O in the atmosphere is the result of human activity, chiefly agriculture.
Nitrous oxide may be used as an oxidiser in a rocket motor. This is advantageous over other oxidisers in that it is much less toxic, due to its stability at room temperature is easier to store and safe to carry on a flight; as a secondary benefit, it may be decomposed to form breathing air. Its high density and low storage pressure enable it to be competitive with stored high-pressure gas systems. In a 1914 patent, American rocket pioneer Robert Goddard suggested nitrous oxide and gasoline as possible propellants for a liquid-fuelled rocket. Nitrous oxide has been the oxidiser of choice in several hybrid rocket designs; the combination of nitrous oxide with hydroxyl-terminated polybutadiene fuel has been used by SpaceShipOne and others. It is notably used in amateur and high power rocketry with various plastics as the fuel. Nitrous oxide may be used in a monopropellant rocket. In the presence of a heated catalyst, N2O will decompose exothermically into nitrogen and oxygen, at a temperature of 1,070 °F.
Because of the large heat release, the catalytic action becomes secondary, as thermal autodecomposition becomes dominant. In a vacuum thruster, this may provide a monopropellant specific impulse of as much as 180 s. While noticeably less than the Isp available from hydrazine thrusters, the decreased toxicity makes nitrous oxide an option worth investigating. Nitrous oxide is said to deflagrate at 600 °C at a pressure of 309 psi. At 600 psi, for example, the required ignition energy is only 6 joules, whereas N2O at 130 psi a 2,500-joule ignition energy input is insufficient. In vehicle racing, nitrous oxide allows the engine to burn more fuel by providing more oxygen than air alone, resulting in a more powerful combustion; the gas is not flammable at a low pressure/temperature, but it delivers more oxygen than atmospheric air by breaking down at elevated temperatures. Therefore, it is mixed with another fuel, easier to deflagrate. Nitrous oxide is a strong oxidant equivalent to hydrogen peroxide, much stronger than oxygen gas.
Nitrous oxide is stored as a compressed liquid. Sometimes nitrous oxide is injected into the intake manifold, whereas other systems directly inject, right before the cylinder to increase power; the technique was used during World War II by Luftwaffe aircraft with the GM-1 system to boost the power output of aircraft engines. Meant to provide the Luftwaffe standard aircraft with superior high-altitude performance, technological considerations limited its use to high altitudes. Accordingly, it was only used by specialised planes such as high-altitude reconnaissance aircraft, high-speed bombers and high-altitude interceptor aircraft, it sometimes could be found on Luftwaffe aircraft fitted with another engine-boost system, MW 50, a form of water injection for aviation engines that used methanol for its boost capabilities. One of the major problems of using nitrous oxide in a reciprocating engine is that it can produce enough power to damage or destroy the engine. Large power increases are possible, if the mechanical structure of the engine is not properly reinforced, the engine may be damaged, or destroyed, during this kind of operation.
It is important with nitrous oxide augmentation of petrol engines to maintain proper operating temperatures and fuel levels to prevent "pre-ignition", or "detonation". Most problems that are associated with nitrous oxide do not come from mechanical failure due to the power increases. Since nitrous oxide allows a much denser charge into the cylinder, it increases cylinder pressures; the increased pressure and temperature can cause problems such as melting valves. It may crack or warp the piston or head and cause pre-ignition due to uneven heating. Automotive-grade liquid nitrous oxide differs from medical-grade nitrous oxide. A small amount of sulfur dioxide is added to prevent substance abuse. Multiple washes through a base can remove this, decreasing the corrosive properties observed when SO2 is further oxidised during combustion into sulfuric
Glass milk bottle
Glass milk bottles are glass bottles used for milk and are reusable and returnable. Milk bottles are used for doorstep delivery of fresh milk by milkmen. After customers have finished the milk they are expected to rinse the empty bottles and leave it on the doorstep for collection; the standard size of a bottle varies with location, common sizes are 1 pint or 1 quart, cream may be delivered in smaller bottles. More plastic bottles have been used for milk; these are made of high-density polyethylene, are used only once, are recyclable. The plastic bottles used for milk are made of three kinds of plastic: the bottle, the lid and the label; these need to be separated. Before the emergence of milk bottles, milkmen would fill the customers' jugs. For many collectors, milk bottles carry a nostalgic quality of a bygone age; the most prized milk bottles are embossed or pyroglazed with names of dairies on them, which were used for home delivery of milk so that the milk bottles could find their way back to their respective dairies.
It is not clear. However, the New York Dairy Company is credited with having the first factory that produced milk bottles, one of the first patents for a milk container was held by the Lester Milk Jar. There are many other similar milk containers from around this period, including the Mackworh Pure Jersey Cream crockery type jar, the Manorfield Stock Farm, the Manor, the Pa glass wide mouth jar, the Tuthill's Dairy Unionville, NY. Lewis P. Whiteman held the first patent for a glass milk bottle with a small glass lid and a tin clip. Following this, the next earliest patent is for a milk bottle with a dome-type tin cap and was granted in September 23, 1884 to Whiteman's brother, Abram V. Whiteman; the Whiteman brothers produced milk bottles based on these specifications at the Warren Glass Works Company in Cumberland and sold them through their New York sales office. The Original Thatcher is one of the most desirable milk bottles for collectors; the patent for the glass dome lid is dated April 27, 1886.
There are several variations of many reproductions. During this time period, many types of bottles were being used to distribute milk; these include a pop bottle type with a wire clamp, used by the Chicago Sterilized Milk Company, Sweet Clover, others. Fruit jars were used, but only the Cohansey Glass Manufacturing plant made them with dairy names embossed on them; the Commonsense Milk Bottle with the first cap seat was developed as an economical means for sealing a reusable milk bottle by the Thatcher Manufacturing Company around 1900. Most bottles produced. By the 1920s, glass milk bottles had become the norm in the UK after being introduced from the US before World War I. Milk bottles before the 1930s were round in shape. In 1935 slender-neck bottles were introduced in the UK. In the 1940s, a square squat bottle became the more popular style. Milk bottles since the 1930s have used ACL to identify the bottles. Before the 1930s, names were embossed on milk bottles using a slug plate; the name was impressed on the slug plate the plate was inserted into the mold used to make the bottle – the result was the embossed name on the bottle.
In 1980 a new bottle, nicknamed "dumpy," was introduced in the UK. From the 1960s onward in the United States, with improvements in shipping and storage materials, glass bottles have completely been replaced with either LDPE coated paper cartons or recyclable HDPE plastic containers, depending on the brand; these paper and plastic containers are lighter and safer to both manufacture and ship to consumers. In 1975, 94% of milk in the UK was in glass bottles, but as of 2012 this number was down to 4%. There are growing concerns among some Americans as to the quality and safety of industrialized milk, the local non-homogenized milk industry has seen a popular resurgence in certain markets in the US in the last decade or so; because of this, the use of glass bottles in local or regional, non-industrial milk distribution has become an common sight. 1880 – British milk bottles were first produced by the Express Dairy Company, these were delivered by horse-drawn carts. The first bottles used. Lewis Whiteman patents the glass milk bottle with a glass lid.
1884 – Dr. Thatcher invents the glass milk container in New York; these were sealed with wooden plugs, which proved unsuccessful, were soon replaced by glass stoppers. 1894 – Anthony Hailwood developed the milk pasteurisation process to create sterilized milk, which could be safely stored for longer periods. 1920 – Advertisements began to appear on milk bottles. A sand-blasting technique was used to etch them on the glass. 1930s – Increased prevalence of battery electric vehicles as milk floats mid 1950s – Cardboard tops were deemed unhygienic and banned in some locations. Delivery by horse-drawn carts was still common. Early 1990s – The advertising disappeared with the introduction of infrared bottle scanners designed to check cleanliness. In some locations around the world, different colored tops on milk bottles indicate the fat content. Unpasteurized is green-topped; however other colour designations may be used by some dairies. Bottles may be marked, stamped or embossed with the name of the dairy.
In the United Kingdom, the aluminium foil tops on glass milk bottles are coloured: Historically, other colors such as Pink for Ultra-High Treated milk, were used. Blue was used for so termed,'sterilized' milk. Modern dairies