The Sterile Period of Alchemy

The Sterile Period of Alchemy

The span of time from about the beginning of the 1st century AD to about the 17th century is considered the period of alchemy. The alchemists believed that metals could be converted into gold with the aid of a marvelous mineral called the philosopher's stone, which they never succeeded in finding or making. They did discover new elements, and they invented basic laboratory equipment and techniques that are still used by chemists. However, the alchemists learned very little that was worthwhile concerning the fundamental nature of matter or of chemical behavior. They failed because their basic theories had almost nothing to do with what actually happens in chemical reactions.

In the 13th century such men as Roger Bacon, Albertus Magnus, and Raymond Lully began to realize how futile it was to search for the philosopher's stone. They suggested that alchemists might rather seek to help the world with useful new products and methods.

In the 16th century, another important leader in the new trend was Theophrastus Bombastus von Hohenheim, an aggressive, talented Swiss who used the Latin name Paracelsus. He insisted that the object of alchemy should be the cure of the sick. The elements, he said, were salt, sulfur, and mercury (long connected with the “elixir of life,” another nonexistent alchemical substance), and they would give health if present in the body in the proper proportions. On this basis he practiced medicine and attracted many followers. Thus began iatrochemistry, or chemistry applied to the study of medicine and the treatment of disease.

One of the first scientific chemists was Robert Boyle. In 1660 he helped found one of the first scientific organizations in Europe, the Royal Society of London. In a book called The Sceptical Chymist (1661) he rejected previous theories of the composition of matter and compiled the first list of the elements that are recognized today. He also discovered the relationship between the volume and the pressure of a gas.

History of Chemistry

History of Chemistry

Modern chemistry is only about two centuries old. The earlier history of chemistry may be divided into three periods: magic; alchemy; and “primitive modern,” a period of transition between alchemyand truly modern chemistry.

The Period of Magic

The period of magic extended from prehistoric times to about the beginning of the 1st century AD. Most people believed that natural processes were controlled by spirits, and they relied on magic to persuade the spirits to help while they conducted practical operations. Very little progress was made toward understanding how the universe is made, but much practical knowledge was gathered. Perhaps 9,000 years ago, people devised reliable techniques for making and sustaining fire. Gradually they learned to use fire to harden pottery, extract metals from ores, make alloys, and develop materials such as glass. Certain elements that occur naturally in a pure state, such as gold, copper, and sulfur, were recognized and valued for their properties. This was the period of the Sumerian, Babylonian, Egyptian, and Greek cultures.

About 400 BC the Greek philosopher Democritus theorized that all matter was made up of tiny, indivisible units he called atoms, but his idea was not based on scientific evidence. Other Greek philosophers, including Thales and Aristotle, also speculated on the nature of matter, though their theories, too, had little in common with modern chemical knowledge. They believed that earth, air, fire, and water (some imagined a fifth substance called “quintessence”) were the basic elements of all matter. They speculated on the possibility of removing such qualities as hardness, heat or cold, and color from common materials and combining them to make rarer or more valuable substances. They knew that iron could be drawn from a dirty, brown earthen rock and that bronze was made by combining copper and tin. Therefore it seemed possible that if yellowness, hardness, and other qualities could be properly combined, the product would be gold. Such speculations gave rise to alchemy.

Atoms and Molecules

Atoms and Molecules

English-russian phrases

English-Russian phrases

       

Common mistakes in the use of pronouns

In this article we will take a look at some common mistakes in the use of pronouns.

Incorrect: Each of these boys play cricket well.

Correct: Each of these boys plays cricket well.

Incorrect: Each of these three roads lead to the railway station.

Correct: Each of these three roads leads to the railway station.

After each of we use a plural noun or pronoun and a singular verb.

Incorrect: Both didn’t go.

Correct: Neither went.

In negative sentences we do not normally use both. Instead, we use neither.

Incorrect: We all did not go.

Correct: None of us went.

In negative sentences we do not normally use all. Instead, we use none.

Incorrect: Each boy and each girl were given a book.

Correct: Each boy and each girl was given a book.

Incorrect: Have you got a pen? I haven’t got.

Correct: Have you got a pen? I haven’t got one.

The verb get needs to be followed by an object.

Incorrect: My all books are lost.

Correct: All of my books are lost.

Incorrect: Let I go.

Correct: Let me go.

Incorrect: Let we move.

Correct: Let us move.

Let is a verb. It should be followed by a pronoun in object form.

Incorrect: Your problem is bigger than me.

Correct: Your problem is bigger than mine.

Correct: Your problem is bigger than my problem.

Incorrect: Whoever does best he will get a prize.

Correct: Whoever does best will get a prize.

Incorrect: I and he are brothers.

Correct: He and I are brothers.

Incorrect: I and Mark are friends.

Correct: Mark and I are friends.

Common Mistakes with English Comparatives and Superlatives

Common Mistakes with English Comparatives and Superlatives

Collocations with make and do

Make or do?

The verbs do and make can be confusing in English because the meaning is similar but they co-occur with different words. For example, you can say:

• do an exercise.   

• The phrase do an exercise is called a collocation.

Definition of collocations

Collocations refer to words that usually go together. They co-occur more often than would be expected by chance.

So how can you distinguish between collocations with make and do?

Generally speaking, use do for activity and make to create something. Compare these examples:

• I always do my homework in the evenings.
• I like spaghetti. I make it everyday

Collocations with make and do

Collocations with do?

Use do when someone performs an action, activity or task.

Examples:

• do
  ...the dishes
  ... an exercise
  ... the laundry
  ... the ironing
  ... the shopping

We use often use do to refer to work of any kind.
Examples:

• do
  ... your work
  ... homework
  ... housework
  ... your job
  ... business
  ... your hair
  ... your nails

Use the verb 'do' when you speak about general things (to describe an action without saying exactly what the action is.)
Examples:

I've got nothing to do today.
He doesn't do anything all day long.
She does everything to attract him.

These are other expressions that you can use with do:
Examples:

• do... one's best
  ... good
  ... harm
  ... a favor
  ... business
  ... things right / badly / well
  ... good
  ... harm
  ... time - (to go to prison)
  ... your best / worst.

Collocations with make?

We use the verb make to construct, build or create. The result is something that you can touch.

They make tea with mint in Morocco.
She makes beautiful dresses.
Let's make a cup of coffee!
can you make a cup of tea?
They make delicious food in this restaurant!

These are some important expressions that you can use with make:

• make
  ... arrangements
  ... an attempt
  ... bed
  ... believe
  ... change
  ... a choice
  ... a comment
  ... a complaint
  ... a decision
  ... a demand
  ... a difference
  ... an effort
  ... an exception
  ... an excuse
  ... an inquiry
  ... a fool of yourself
  ... a fortune
  ... friends
  ... a fuss
  ... a journey
  ... love
  ... a mess
  ... a mistake
  ... money
  ... a move
  ... a noise
  ... an offer
  ... peace
  ... a phone call
  ... a plan
  ... a point
  ... a profit
  ... a promise
  ... a remark
  ... a sound
  ... a speech
  ... a suggestion
  ... time
  ... a visit
  ... war