PASSAGE 1
Another find was a section of traditional Roman mosaic. Although incomplete, enough pieces remain to show a geometrical pattern and stylized fish. From this, Durrand assumes that a bath house would have been a feature of the villa. While his team have so far not found any hard proof of this, Durrand is confident it will turn out to be the case.
Something that team particularly excited about is evidence of a heating system, which would have served the Roman family and their visitors well in winter months. Although much of the system has long since crumbled at Hensham, Durrand and his team believe it would have been based on a typical Roman hypocaust; they have created a model for visitors to see. The furnace that produced the hot air needed to be kept burning all the time, a task that would have fallen to the villa's slaves. As large branches would have taken too long to produce the heat required, it is more likely that twigs would have been gathered from surrounding woodland instead. Another fuel source used in some Roman hypocausts was charcoal, but evidence for this at Hensham has not presented itself. The underfloor space was made by setting the floor on top of piles of square stones. Known as pilae, these stones stood approximately two feet high. The gap this created meant that the hot air coming out of the furnace was not trapped and restricted. Instead its distribution around the pilae and under the floor was free flowing. Floor tiles were not placed directly onto the pilae but separated by a layer of concrete, or at least a primitive version of it. This would have made the whole structure more solid, and helped reduce the risk of fire spreading to upper levels. The walls of the rooms above heating system were made of bricks, but the key point here is that they were hollow, in order to allow heat to rise around the rooms and provide insulation. Some have been recovered from the Hensham villa and are now undergoing preservation treatment.
Another feature of the heating system that archaeologists have identified at Hensham was its clay pipes. These were cleverly built into the wall so as not to take up space. The principal reason for including the pipes was to let out air through a vent in the roof once it had cooled down. What the Romans may not have realised, however, was that gas produced by the burning fuel was expelled in this way too. In high doses, it could have been lethal if it had leaked into the upper levels. Inside the rooms in the villa, a layer of plaster would have been applied to the walls and painted in rich colours. Sadly, none of the original plaster at Hensham still exists. However, some of the tiles that the family would have walked on have survived. They would certainly have felt warm underfoot and helped generate an indoor climate that the family could relax in. In its day, the Hensham hypocaust would have been a remarkable piece of engineering.
PASSAGE 2
This is possible because in freeze-drying, solid water - ice - is converted directly into water vapour, missing out the liquid phase entirely. This is called 'sublimation', the shift from a solid directly into a gas. Just like evaporation, sublimation occurs when a molecule gains enough energy to break free from the molecules around it. Water will sublime from a solid (ice) to a gas (vapour) when the molecules have enough energy to break free but the conditions aren't right for a liquid to form. These conditions are determined by heat and atmospheric pressure. When the temperature is above freezing point, so that ice can thaw, but the atmospheric pressure is too low for a liquid to form (below 0.06 atmospheres (ATM)) then it becomes a gas.
The is the principle on which a freeze-drying machine is based. The material to be preserved is placed in a freeze-drying chamber which is connected to a freezing coil and refrigerator compressor. When the chamber is sealed the compressor lowers the temperature inside it. The material is frozen solid, which separates the water from everything around it on a molecular level, even though the water is still present. Next, a vacuum pump forces air out of the chamber, lowering the atmospheric pressure below to 0.06 ATM. The heating units apply a small amount of heat to the shelves in the chamber, causing the ice to change phase. Since the pressure in the chamber is so low, the ice turns directly into water, which leaves the freeze-drying chamber, and flows past the freezing coil. The water vapour condenses onto the freezing coil in the form of solid ice, in the same way that water condenses as frost on a cold day.
The process continues for many hours (even days) while the material gradually dries out. This time is necessary to avoid overheating, which might affect the structure of the material. Once it has dried sufficiently, it is sealed in a moisture-free package. As long as the package is secure, the material can sit on a shelf for years and years without degrading, until it is restored to its original form with a little hot water. If everything works correctly, the material will go through the entire process almost completely unscathed.
In fact, freeze-drying, as a general concept, is not new but has been around for centuries. The ancient Incas of Peru used mountain peaks along the Andes as natural food preservers. The extremely cold temperatures and low pressure at those high altitudes prevented food from spoiling in the same basic way as a modern freeze-drying machine and a freezer.
PASSAGE 3
The origins of the dingo are obscure, and there is much controversy connected with this. It is not truly native to Australia but is thought to have arrived between 3,500 and 4,000 years ago. Whatever its origins, the dingo was a highly valued companion to the aborigines. They were hunting companions, guard dogs, and they kept them warm at night.
The dingo can be found in all areas of Australia - from harsh deserts to lush rainforest The highly adaptable dingo is found in every habitat and every state of Australia, except Tasmania. In deserts, access to drinking water determines where the animal can live. Purebred dingo numbers in the wild are declining as man encroaches deeper and deeper into wilderness areas, often accompanied by his domestic dog.
The dingo is different from the modern dog in several ways: it does not bark, it has a different gait, and its ears are always erect. Dingoes are naturally lean, and they are usually cream to reddish-yellow with white points, some are black with tan points. An adult dingo stands more than 60cm high and weighs about 15kg. It is slightly smaller than a German Shepherd.
In its natural state, the dingo lives either alone or in a small group, unlike many other wild dog species which may form packs. Dingoes have a clearly defined territory which they rarely leave and which they protect from other dingoes, but which may be shared with dingoes when they form a group to hunt larger prey. The size of the home territory varies according to the food supply. Dingoes hunt mainly at night. Groups are controlled by dominant male. Members of a group maintain contact by marking rocks and trees within the territory, and by howling, particularly in the breeding season.
The dingo's diet consists of native mammals, including kangaroos, although domestic animals and some farmstock are also on the menu. This makes the animal unpopular with farmers. The dingo is thought to have contributed to the mainland extinction of the thylacine through increased competition for food.
The dingo is an intelligent animal. It is no more dangerous to man than any other feral dog. The natural prey of the dingo is small mammals and ground-dwelling birds, but with the introduction of white settlement, they became such a menace to sheep, calves and poultry that measures had to be taken in an attempt to control them, such as dog-proof fences.
Dingoes and domestic dogs interbreed freely resulting in very few pure-bred, southern or eastern Australia. This threatens the dingo's ability to survive as a separate species. Public hostility is another threat to the dingo. Because it takes some livestock, the dingo is considered by many to be a pest.
PASSAGE 4
In 1856, during his vacation, he was trying to manufacture quinine from aniline (inexpensive and readily available coal tar waste) in his laboratory at the top of his family's house. Out of his best efforts, he didn't get the quinine, but some mysterious dark sludge. Fortunately, Perkin's scientific training and nature made him explore the substance further. At the various stages of the experimental process, he added the potassium dichromate and alcohol into the aniline which produced a deep purple solution. Louis Pasteur's words 'chance favours only the prepared mind', proved to be true, he saw the unexpected potential of his find.
Usually, the textile dye was made from natural resources such as plants and animal excretions. Few of these, like glandular mucus of snails, were both expensive and difficult to get. At that time, the rich can only afford the purple colour which is extracted from the snail as this is so costly. Moreover, the tendency of the natural dyes is found to be muddy in hue and fade quickly. Perkin's discovery was against this backdrop.
Perkin understood that his purple solution could be used for colour fabric, which is the world's first synthetic dye. He patented it as he realised the importance of his finding. One of the fascinating reactions of Perkin quickly found that the new dye has commercial possibilities.
Originally, Perkin named his dye Tyrian Purple. Later, it became commonly known as mauve. By asking advice to the Scottish dye works owner Robert Pullar, he understood that the dye manufacturing would be worthwhile if the colour remained fast (i.e. would not fade) and if it is relatively low cost. His mentor Hofmann objected to him in a fierce manner, so he left the college and gave birth to the modern chemical industry. Perkin set up a factory, near London, with the help of his father and brother. Coal tar is cheap and plentiful as this is an almost limitless by-product of London's street lighting. The dye works started producing the world's first synthetically dyed material in 1857. The Empress Eugenie of France, boosted the commercial part of the company as the new colour flattered her. Mauve becomes a necessary shade for all the fashionable ladies in that country.
In public, England's Queen Victoria appears wearing a mauve gown which brought rage in England. The dye was both fast and bold, and the public demand was increased. Perkin returns to the drawing board.
Though Perkin's first discovery itself brought him fortune and achievements, the chemist continued his research. He developed and introduced several other dyes including aniline red (1859) and aniline black (1863) and Perkin's green in the late 1860s. Perkin's synthetic dye discoveries resulted in more than just decorative purposes. The dyes also become important to medical research in many ways. For example, researchers are able to identify such bacilli as tuberculosis, cholera and anthrax, which were the invisible microbes and bacteria before. Artificial dyes continue to play an important role even today. Its current use in the search for a vaccine against malaria, which could have pleased the Perkin.
Questions 8 - 13
Label the diagram below.
Choose NO MORE THAN TWO WORDS from the passage for each answer.
A model of the heating system used at Hensham villa
8. were constantly added to the furnace by slaves.
9. The height of the pilae helped with the of air produced by the furnace.
10. Builders used as a material for this part.
11. The use of meant walls were well insulated.
12. Cold air escaped from pipes, as well as dangerous .
13. Fitted surfaces created a comfortable climate.
Questions 6 - 9
Label the diagram below.
Choose NO MORE THAN TWO WORDS from the passage for each answer.
6.
7. with heating units
8.
9.
Questions 1 - 8
Answer the questions below.
Choose NO MORE THAN THREE WORDS from the passage for each answer.
1. What factor decides where the dingo can live in a desert?
2. Which physical characteristic distinguishes a dingo from a domesticated dog?
3. What term refers to a group of wild dogs?
4. What determines the vastness of the area occupied by the dingoes?
5. Which landscape features are used by the group to remain connected?
6. What animal might have been wiped out due to the dingo?
7. What has been made to protect the livestock from the dingoes?
8. What do many people regard the dingo as?
Questions 8 - 13
Answer the questions below.
Choose NO MORE THAN TWO WORDS from the passage for each answer.
8. Before Perkin's discovery, with what group in society was the colour purple associated?
9. What potential did Perkin immediately understand that his new dye had?
10. What was the name finally used to refer to the first color Perkin invented?
11. What was the name of the person Perkin consulted before setting up his own dye works?
12. In what country did Perkins' newly invented colour first become fashionable?
13. According to the passage, which disease is now being targeted by researchers using synthetic dyes?