IELTS Academic Reading Practice Test 38

Soap is so ordinary that few people stop to consider how it works or how long it has been made. Chemically, it is the product of a reaction known as saponification, in which fats or oils are combined with a strong alkali. The reaction produces two substances: soap itself and glycerol, a sweet, syrupy liquid. A soap molecule has an unusual structure. One end is attracted to water, while the other, a long chain of carbon atoms, is attracted to grease and oil. When soap is mixed with water and rubbed on a dirty surface, the oily ends cling to grease and the water-loving ends face outwards, so that the dirt is lifted away and held in tiny droplets that can be rinsed off.

Some of the earliest evidence for soap-like substances comes from ancient Mesopotamia, where texts written on clay several thousand years ago describe fats being boiled with ashes. An Egyptian medical document known as the Ebers Papyrus, dating from around 1550 BCE, records that animal and vegetable oils were combined with alkaline salts to make a substance used both for washing and for treating diseases of the skin. Yet soap was not always valued as a cleaning agent. The Roman writer Pliny the Elder described it as an invention of the Gauls, who used it to redden their hair, while wealthy Romans themselves usually cleaned their bodies by rubbing in oil and scraping it off with a curved metal tool called a strigil.

For most of history, the quality of soap depended on where its alkali came from. In much of northern Europe, soapmakers soaked wood ash in water to obtain lye, a caustic solution containing potash. Combined with animal fat, this produced soft soap, a brownish paste that was effective but often unpleasant to handle and smell. Around the Mediterranean, by contrast, soapmakers burned coastal plants such as saltwort, whose ashes are rich in soda.

Soda reacts with fats to produce hard soap, and when it was combined with olive oil the result was a firm, pale bar that could be stored and traded over long distances. The olive-oil soaps of Aleppo in Syria, of Castile in Spain and later of Marseille in France became famous throughout Europe and the Middle East.

The traditional method of manufacture changed little over many centuries. Fat and lye were heated together in a large kettle for hours or even days, and the soapmaker judged the progress of the reaction by its appearance and texture. When the mixture was ready, salt was added. Because soap does not dissolve easily in salty water, it separated from the liquid and rose to the surface as a thick layer of curds, leaving the excess lye and the glycerol below. The soap was skimmed off, sometimes boiled again to purify it, and then poured into wooden frames, where it hardened over several days. Finally, the solid block was cut into bars, which were left to dry for weeks before they were sold.

Two developments around the beginning of the nineteenth century transformed this craft into an industry. The first was the Leblanc process, patented in France in 1791, which made soda from common salt and so freed soapmakers from their dependence on plant ashes. The second was scientific. In 1811 the French chemist Michel Eugène Chevreul was asked to examine a sample of soap, and his research over the following years showed that fats are compounds of glycerol and substances he called fatty acids. His book on the subject, published in 1823, explained for the first time what actually happens during saponification, allowing manufacturers to control the process precisely rather than relying on experience and guesswork.

In Britain, the spread of soap was held back for well over a century by taxation. A duty on soap was introduced in 1712 and was charged according to weight rather than value, so that cheap soaps used by poorer households were taxed as heavily as expensive ones. It was finally abolished in 1853 by the Chancellor of the Exchequer, William Gladstone.

Three decades later, William Hesketh Lever and his brother began selling Sunlight soap, which was made with vegetable oils rather than tallow. Instead of being cut from a long bar by the grocer and sold by weight, it was supplied in individual wrapped pieces bearing a brand name. This approach to marketing was highly successful, and in 1888 Lever began building a large factory and a village for his workers, called Port Sunlight, beside the River Mersey.

During the twentieth century, soap faced competition from synthetic detergents. These were developed partly because of shortages of fats in Germany during the First World War, and they had the advantage of working well in hard water, where ordinary soap leaves a grey scum. Detergents now dominate laundry and dishwashing products, but soap remains the standard choice for washing the body. Its importance was underlined during the COVID-19 pandemic, when health authorities emphasised that thorough handwashing with soap helps to break apart the fatty outer layer that surrounds many viruses, including the coronavirus. A substance first made from fat and ashes thousands of years ago thus continues to play a role in protecting public health.

Few natural resources are as easy to overlook as sand. It seems endlessly abundant, and most people encounter it only on beaches or in children's playgrounds. Yet sand, together with gravel and crushed rock, is the raw material of the modern built environment. It is the main ingredient of concrete and asphalt, it is melted to make glass, and highly purified forms of it are used to produce the silicon in computer chips and solar panels. According to the United Nations Environment Programme (UNEP), sand, gravel and similar aggregates are the most heavily exploited natural resources in the world after water, with somewhere between 40 and 50 billion tonnes extracted every year – far more than natural processes can replace. Because sand is cheap, heavy and usually extracted close to where it is used, it has rarely attracted the attention of policymakers, and in many countries nobody knows exactly how much is being removed or by whom.

It may seem strange to speak of a shortage when vast deserts cover large parts of the planet. The problem is that most desert sand is unsuitable for construction. Grains that have been blown around by the wind for thousands of years become smooth and rounded, and they do not lock together well enough to make strong concrete. Builders need more angular grains, which are found mainly in riverbeds, lakes, coastal areas and the seabed. Even marine sand has drawbacks: it must be thoroughly washed to remove salt, which would otherwise corrode the steel bars used to reinforce concrete structures.

Demand has grown rapidly because of urbanisation. Concrete is now the most widely used construction material on Earth, and most of its volume consists of sand and gravel bound together by cement. Over recent decades, hundreds of millions of people have moved into cities, particularly in Asia and Africa, and each new apartment block, road, bridge and airport requires enormous quantities of concrete. China's building boom alone has absorbed a huge share of the world's sand, and India, Indonesia and many African countries are now following a similar path. As populations continue to grow and cities expand, UNEP expects global demand for sand to keep rising unless the way buildings are designed and constructed changes substantially.

Much of this sand is taken from rivers, where the consequences of over-extraction can be severe. Removing sand lowers the level of riverbeds, which can undermine the foundations of bridges and embankments and cause banks to collapse. It also destroys the habitats of fish and other aquatic creatures. Because rivers carry sediment downstream, sand removed in one place can also deprive beaches and deltas far away of the material that would naturally replenish them. In the Mekong Delta in Vietnam, intensive sand mining, combined with the effects of upstream dams, has been linked to the erosion of riverbanks and the loss of land. As the delta sinks and shrinks, salt water from the sea penetrates further inland, damaging the rice fields on which millions of people depend.

Increasingly, sand is also being removed from the ocean floor. In 2023 UNEP launched Marine Sand Watch, a platform that tracks the movements of dredging vessels using the signals ships transmit and artificial intelligence. Its first estimates suggested that between four and eight billion tonnes of sand are dredged from the world's seas every year. Dredging can effectively sterilise the seabed, removing the organisms that live in it and leaving little for fish to feed on, and it may also make coastlines more vulnerable to erosion. Because much of this activity takes place far from shore, it has until recently been very difficult to monitor. The platform has also revealed that a noticeable share of dredging takes place inside marine protected areas, where such activity might be expected to be tightly controlled.

Sand has also become an object of international trade and, in some places, of crime. Singapore has expanded its land area by roughly a quarter since the 1960s, largely by reclaiming land from the sea, and it is the world's largest importer of sand. Neighbouring countries have at times restricted their exports: Indonesia banned sand exports in 2007, citing environmental damage, and Cambodia later imposed its own restrictions. Where regulation is weak, illegal extraction flourishes. In India, criminal groups known as sand mafias control parts of the trade, and journalists, activists and officials who have tried to expose them have been threatened, attacked and in some cases killed.

Experts argue that the solution lies not in a single technology but in treating sand as a strategic resource. A UNEP report published in 2022 recommended that governments map and monitor their sand resources, regulate extraction more effectively and reduce unnecessary consumption. Waste from construction and demolition can be crushed and recycled to replace some natural sand, and so-called manufactured sand, produced by crushing rock, is already widely used in India. Architects and engineers can also help by designing buildings that use less concrete, or by extending the life of existing structures rather than replacing them. Some researchers have also experimented with making concrete from desert sand that has been specially processed, although such techniques are not yet in widespread use. None of these measures is free, but the cost of continuing as before may prove considerably higher.

Twice a year, in dozens of countries across Europe and North America, people move their clocks forward or back by an hour. Some places have already abandoned the practice; most of the American state of Arizona, for example, keeps the same time all year. Elsewhere, the ritual is so familiar that it is easy to assume it must serve some important purpose. In my view, however, the case for seasonal clock changes has largely collapsed. The question that now deserves attention is not whether the changes should end, but which time we should keep once they do – and on that question, I believe, the evidence points in a less popular direction than many politicians would like.

The idea has a curious history. Benjamin Franklin is often credited with inventing it, but his famous essay of 1784, which suggested that Parisians could save money on candles by getting up earlier, was a joke rather than a policy proposal. A more serious suggestion came in 1895 from George Vernon Hudson, a New Zealand entomologist who wanted more daylight after work to collect insects and proposed a two-hour seasonal shift.

In 1907 the British builder William Willett published a pamphlet called The Waste of Daylight, arguing that clocks should be advanced gradually in spring. Willett campaigned for years without success and died in 1915. It took the First World War to turn the idea into law: on 30 April 1916 Germany became the first country to adopt daylight saving time nationally, hoping to conserve fuel, and Britain followed within weeks.

Energy saving remained the main justification for decades, but modern evidence offers it little support. When the American state of Indiana adopted daylight saving time across all its counties in 2006, economists Matthew Kotchen and Laura Grant treated the change as a natural experiment. They found that it increased household electricity demand by around one per cent, apparently because savings on lighting were outweighed by extra heating on dark mornings and extra air conditioning on warm evenings. An earlier experiment had been even less successful. During the oil crisis of the 1970s, the United States moved to year-round daylight saving time, but in winter the sun rose as late as nine o'clock in some places, and the plan was abandoned within a year as public opinion turned against it.

Meanwhile, concern about health has grown. The spring change costs most people an hour of sleep, and the body may take days to adjust. A study published in 2020 in the journal Current Biology found that the risk of fatal road accidents in the United States rose by about six per cent in the week after the spring transition, with larger increases in the western parts of time zones, where mornings are darker. Researchers have also reported more heart attacks and workplace injuries in the days following the change. Most of these studies show associations rather than direct proof of cause, and the risk to any individual is small, but the effects apply to entire populations at once. Whatever the precise size of these effects, they represent a real cost paid every year for a benefit that is difficult to identify.

If the clock changes should end, the obvious temptation is to keep summer time permanently. Light evenings are popular, and businesses that depend on leisure and shopping favour them. In March 2022 the United States Senate passed the Sunshine Protection Act, which would have made daylight saving time permanent, without a single objection. The bill was never voted on in the House of Representatives, however, and history suggests caution. Russia adopted permanent summer time in 2011, but dark winter mornings proved so unpopular that in 2014 the country moved to permanent standard time instead.

Sleep scientists have been clear about their preference. In 2020 the American Academy of Sleep Medicine called for the seasonal changes to be abolished in favour of permanent standard time, a position endorsed by many other medical organisations. Their reasoning rests on the biology of the body clock, the internal rhythm that regulates sleep, alertness and hormone release. This clock is reset each day mainly by light, and morning light is particularly important. Standard time keeps the clock on the wall roughly aligned with the sun. Permanent summer time would push many people's working and school days earlier relative to sunrise throughout the winter, creating a chronic mismatch that researchers call social jet lag.

Europe illustrates how difficult change can be even when there is broad agreement. In 2018, following a public consultation in which a large majority of respondents favoured ending the clock changes, the European Commission proposed doing exactly that, and the European Parliament supported the proposal in 2019. Since then, progress has stalled. Member states have been unable to agree on whether to keep summer or winter time, and many fear that a patchwork of different decisions would disrupt trade and travel across the continent.

None of this means the decision is simple. Permanent standard time would mean that summer evenings grow dark an hour earlier than people are used to, and that loss would be noticed. But a clock policy should be judged by its effects on health and safety, not by how pleasant it feels on a June evening. The sensible course is to end the twice-yearly changes and to keep standard time throughout the year, while coordinating the decision closely with neighbouring countries.