After the news of the discovery of gold mines in California was confirmed, it triggered another wave of immigration. People leave their jobs at hand and flock to San Francisco, trying to realize their dream of gold rush. /kloc-At the beginning of the 9th century, the United States began an unstoppable westward movement, pushing the American frontier from the Mississippi River to the west coast of the Pacific Ocean.
1848, people who went to California discovered a gold mine here, which immediately caused a sensation in the world and quickly formed an unprecedented gold rush, which had a great impact on the westward movement and the development of the western United States. The gold rush is an important part of the westward movement, just like a bright fragment on a magnificent picture.
The California gold rush is the product of the westward movement, which is closely related to the westward movement in American history. It directly originated from a series of activities of people in the westward movement: First, the gold mine discovered in California in 1848 is located in the Sartre community in New Irvine, which is located at the intersection of the Sacramento River and the American River. It is one of the two largest early colonies of American immigrants on the Pacific coast, which was built by American immigrant Sartre in 1848; Secondly, Marshall, the discoverer of the gold mine, was an American immigrant who conquered the Pacific coast. He was born in capitalist New Jersey. 1844, he embarked on a journey to the west, moved from Missouri to Oregon, and settled in Sartre community the following year. Once again, a gold mine was discovered in the diversion ditch of the waterwheel of Marshall and Sartre sawmills. When the gold rush broke out, the wood processing here immediately solved the urgent needs of gold miners' production and life.
In fact, before this, gold mines have been discovered many times along the Pacific coast. According to the records, a large gold mine was discovered near Los Angeles in 184 1 and in Southern California in 1842.
These two times did not have a shocking impact. Although the discovery of the gold mine in 1842 attracted hundreds of gold prospectors, it soon fell silent. This is because several discoveries before 1848 occurred in India, and Indian society was still in a rather primitive state, and they did not understand the economic value of gold.
Moreover, at that time, there were few immigrants here, the development of commodity economy was low, and the contact with the outside world was limited. The news of the discovery of gold mines could not be spread. However, by 1848, the westward movement had greatly improved this situation.
With the continuous entry of immigrants, the continuous development of economic production and closer contact with the outside world, things like discovering gold mines will no longer be "always local". 1848 1 24, a gold mine was discovered; On March 15, San Francisco's California newspaper first published this news; On May 12, merchant Branna came to San Francisco from the gold mining area with samples of Jinsha, which confirmed the news of the discovery of gold mine. On August 19, a letter describing this discovery was published in the Herald in new york, USA, and the news spread almost all over the world.
The gold rush began. The westward movement not only means the expansion of American territory, but also makes the commodity economy and capitalist mode of production widely spread and transplanted in North America.
1In the 1940s, the development of Americans in California, as well as their way of thinking, behavior norms and interpersonal relationships, formed the cultural background of the gold rush in full swing. The sawmill mentioned above is operated in a modern way.
According to the contract, Sartre provided the necessary funds for the sawmill, Marshall, who was in charge of the operation, paid a quarter of the product, and the personnel management adopted the mode of wage labor. Branna, who made the news of the discovery of gold mine "finally spread all over the world", was an "adventurous businessman, manipulator and land speculator". He founded a series of enterprises in California and set up a "head office" in Sartre community.
1848 In March, the regular customers of this head store began to propose to pay the price of whisky and other commodities with gold, and Branna immediately realized the significance of this discovery. So, realizing that there would be unlimited business opportunities, he immediately tried his best to raise goods to meet customers' demand for their goods, and then got a lot of gold sands.
The activities and relationships of these three people were a microcosm of society at that time, reflecting that the rise of the gold rush was related to the adjustment of the market economy. This connection was created by the westward movement.
The "outbreak" and progress of the gold rush in California were also directly promoted by the United States. From the overall situation, the United States attaches great importance to the westward movement and has been fully supporting American cowboys to overcome difficulties in the west; Specifically, before and after the gold rush, the United States was preparing to formally annex California.
At that time, the United States had just finished the Mexican War and realized its "destiny". The idea of turning California into another star on the American flag was the general trend. * * * It needs a large number of Americans to enter California, so that the population in this area can meet the legal requirements of applying for * * * in the name of the state.
1848 in June, Mei Sen, the governor of California, sent a special report to President Polk, saying that the value of the gold mine was "enough to pay for the Mexican war many times this". 1February 5, Polk officially released this report in his speech to Congress, which confirmed the discovery of gold mines in California.
Many skeptics in the eastern United States suddenly realized that they immediately moved west and flocked to California. When the gold rush led to a sharp increase in population, which in turn affected the shortage of commodities, the United States * * * tried to regulate and co-ordinate the supply of commodities, and even sent a delegation to China, asking China businessmen to directly transport commodities to California.
All these reflect the role and influence of * * *. After the news of the discovery of gold mines in California was confirmed, the United States boiled and the world was shocked.
San Francisco, which is close at hand, first felt the impact of the gold rush. "Almost all enterprises stopped working, sailors abandoned their ships in San Francisco Bay, soldiers left their barracks, servants left their owners and flocked to the gold mine discovery site"; "Farmers pawned the farmhouses, pioneers gave up land reclamation, workers dropped their tools, and civil servants left their desks.
2. What is thermal analysis and how does it develop? The development history of thermal analysis can be traced back to more than 200 years ago.
1780, in the process of studying lime binder and quicklime, Higgins of Britain used a balance to measure the weight change during experimental heating for the first time. 19 15, Japanese Bendo Kotaro put forward the concept of "thermal balance" and designed the world's first thermal balance. 1899, Roberts and Austen of Britain connected two thermocouples in reverse phase, and directly recorded the law of temperature difference between sample and reference substance with time by differential thermal analysis. After World War II, thermal analysis technology developed rapidly, and commercial electron tube differential thermal analyzer appeared in the late 1940s, and it was miniaturized in the 1960s.
1964, Wattson and O'Nei 1 1 and others put forward the concept of "differential scanning calorimetry", and then developed into differential scanning calorimetry technology, which made the thermal analysis technology develop continuously.
3. What is "heat"? There have been different views since ancient times.
16th century later, the nature of heat attracted the attention of scientists and researchers. "Heat" is a kind of exercise. Bacon concluded from the phenomena of friction and heat generation that "heat is an expanding and restrained movement, which acts on the smaller particles of an object in its struggle", which influenced many scientists.
Boyle saw that the nail would generate heat after being hammered, and thought that there was a strong movement inside the nail, so he thought that heat was "a strong and chaotic movement of all parts of the object"; Descartes thinks that heat is a kind of rotating motion of matter particles. Hooke observed sparks with a microscope and thought that heat was "nothing but a very active and violent movement of all parts of an object."
Newton also pointed out that the particles of an object "heat up because of motion." Locke even realized that "extreme cold is an imperceptible stop of particle motion".
Russian scholar lomonosov published two physics papers in11940s. The first one is about the basis of thermodynamics, and the topic is thinking about the causes of heat and cold (1746). The second article is about the theory of molecular motion, entitled "On the Elasticity of Air" (1748). In these two papers, lomonosov put forward the following viewpoints: "The sufficient root of heat lies in motion", that is, heat is the motion of matter, and motion is the tiny particles invisible to the naked eye in objects; The particle itself is spherical, because only in this way can the solid maintain its shape when heated; The reason why heat is transferred from a high-temperature object to a low-temperature object is that particles in a high-temperature object transfer motion to particles in a low-temperature object, and the amount of exercise given is equal to the amount of exercise received. When an object heats another object, it will cool itself, which affirms the correctness of the conservation of motion in thermal phenomena. The movement of gas molecules presents a state of "mixed * * wrong", which is chaotic and irregular.
"Heat" is a substance, but generally speaking, the view that heat is movement lacks sufficient experimental basis, so it cannot form a scientific theory. With the revival of atomism in ancient Greece, the view that heat is a special material entity began to spread.
Gassendi, a French scientist and philosopher, believes that the moving atom is the most primitive and inseparable element in the world, which constitutes everything. Similarly, heat and cold are caused by special "hot atoms" and "cold atoms". They are very detailed, have the shape of a ball and are very lively, so they can penetrate into all objects.
This concept leads people to "heat theory". Boyle also wavered between thermal motion theory and heat theory.
When investigating the phenomenon that a hot iron placed in a vacuum container can make the wall feel hot, he thinks that it can only be explained by "heat" itself. Polhaf believes that the source of heat is highly plastic and penetrating material particles drilled in the pores of objects, which have no weight and repel each other and are all over the universe.
In 1789, lavoisier also listed "heat mass" and "light" among 23 "elements" in the inorganic field. Blake is an important advocate of heat theory.
Although he thinks that the current heat will eventually occur "not chemically, but mechanically", he can hardly deny the heat theory. He thinks that there are still many difficulties in the theory that heat is exercise.
For example, if heat is the movement of particles inside a substance, then a dense substance is not easy to vibrate because of the strong attraction of internal particles, and its specific heat should be greater, but why is the specific heat of mercury smaller than that of water? It is difficult to explain "latent heat" by the mechanical motion of particles. So Blake declared that he "could not form this concept of internal vibration" and adopted the view that heat is a special substance.
The theory of heat simply explains most of the thermal phenomena found at that time: the change of object temperature is caused by absorbing or releasing heat mass; Heat conduction is the flow of heat mass, convection is the flow of objects carrying heat mass, and radiation is the spread of heat mass; The object expands when heated because the hot particles repel each other; The "latent heat" when the state of matter changes is the result of "quasi-chemical reaction" between particles and thermal mass; The phenomenon of heat generated by friction or collision is the same as that of "latent heat" being squeezed out and the specific heat of matter becoming smaller. Wait a minute. Because of the materiality of heat mass, it also obeys the law of conservation of matter, which is the theoretical basis of mixed calorimetry.
Under the guidance of heat theory, the main progress in thermal research is as follows: Blake discovered specific heat and "latent heat"; Watt theoretically analyzed the main defects of the old steam engine and guided him to improve it. Fourier established the heat conduction theory based on this physical image; From the viewpoint of heat and mass transfer, Carnot put forward the theory of doing work by consuming heat from a heat source at the beginning of19th century. The success of heat theory convinced people that it was a correct theory, thus overwhelming the viewpoint that heat is a kind of movement, and it occupied a dominant position from18th century to19th century.
"Heat" is still a sport, but by the end of18th century, the heat theory was seriously challenged. 1798, Benjamin Thompson, a physicist who was born in the United States and later became a British citizen, submitted a report to the Royal Society, saying that when he was supervising the barrel drilling work in Munich, he noticed that the barrel temperature increased, and the metal chips drilled out were even hotter. He raised the question of where a lot of heat came from.
He conducted a series of drilling experiments under the condition of thermal insulation as much as possible, and compared the specific heat of metal and debris before and after drilling. It was found that drilling and grinding would not change the specific heat of metal. He also drilled holes in the barrel with a blunt drill. After half an hour, the barrel was heated from 60 degrees Fahrenheit to 130 degrees Fahrenheit, and the metal fragments were only over 50 grams, which was equivalent to one ninth of the barrel's mass. Can such a small amount of debris release such a large "latent heat"? He wrote in his notes: "It seems that in these experiments, the sources of heat generated by friction are inexhaustible.
Needless to say, anything that can be provided by an isolated object or system can never be a concrete material entity; In my opinion, the heat excited in these experiments can hardly be considered as anything else except' movement'. "Six years later, thermal mass theorists still advocate the Renford experiment.
4. What is the nature of heat?
One of the earliest natural phenomena that human beings come into contact with in life and production is the thermal phenomenon.
What exactly is heat,
Historically, yes.
There is a long-standing argument here.
From prehistoric times until
18
At the beginning of this century,
Although people have made many explorations on the nature of thermal phenomena,
However, due to the lack of rich knowledge and scientific methods, the understanding of the nature of heat is only some ideas.
18
hundred years
First arrival
19
In the middle of the century, the appearance and wide use of steam engines promoted the rapid development of industry. In order to further improve the heat engine
Efficiency,
In-depth study of the thermal properties of matter,
Thus promoting the development of thermal experiments,
Since then, there has been no research on thermal phenomena.
On the road of experimental science.
In order to quantitatively explain the experimental results,
According to one-sided experimental facts, some scholars believe that,
Hot is
A liquid without mass is called thermal mass;
But heat theory can't explain friction heating,
Impact fever and other phenomena. Other scholars
It is believed that heat is not a fluid, but a manifestation of material movement.
1842
German doctor
J
.
rare
Meyer's paper mentioned that
According to the principle of conservation of energy, he thinks that heat is a kind of energy which can be converted with mechanical energy. then
J
.
P
Joule before and after
It took decades to do many experiments,
Measuring the mechanical equivalent of heat,
The results are exactly the same,
So as to conserve energy.
And laid a solid foundation for the transformation law.
1
Heat theory and the development of calorimetry.
Ancient atomists believed that heat was a substance; Modern Gassendi (
Gassendi
Pierre
,
1592
~
1655
) Ye Ming
It is true that the concepts of "hot atom" and "cold atom" are put forward, and it is believed that an object is warming up because "hot atom" is working. Gasan
Although Germany's theory is only speculative,
But it was valued by later physicists.
Thus, the heat theory was developed.
thermal
It is said that heat is a self-repulsive weightless fluid called thermal mass. It is immortal and can permeate everything.
In the object. Is an object "hot" or "cold"
It depends on how much heat it contains. Hot objects contain more.
Thermal mass,
When two objects with different heat and cold contact,
Hot substances are released from hot objects into cold objects,
Until the temperature of both.
The degree is the same.
Heat theory can really explain most of the thermal phenomena encountered at that time:
Changes in the temperature of an object can be regarded as absorption or release.
Caused by hot substances,
Heat conduction is the flow of thermal mass,
Objects expand when heated, because hot particles repel each other.
Latent heat is matter.
The result of a chemical reaction between particles and hot particles.
Because thermal mass is a substance;
The reduced thermal mass of an object,
just in time
Equal to the increased thermal mass of another object;
Therefore, heat and mass are conserved in the process of transmission;
That is, obey the law of conservation of matter.
thermal
These advantages won the recognition of most scholars at that time.
1738
In, the French Academy of Sciences offered a reward for studying the nature of fever.
Thesis,
All three winners are supporters of heat theory.
It can be seen that the theory of heat was accepted by many people at that time.
Because of this kind of learning
It can directly explain some physical phenomena and experimental results, so it has been widely recognized.
Thermology begins with the quantitative study of thermal phenomena.
The first sign of quantitative research is to measure the temperature of an object.
as far back as
In the last century,
Galileo has made the first thermometer,
In the future, members of the Italian Zimanto Society will continue to study.
Thermometer.
The basic basis of temperature measurement is that materials expand when heated and contract when cooled.
Secondly, there must be an agreed scale system.
Galileo's temperature
The instrument utilizes the expansion and contraction of air when it is heated,
But there is no fixed scale.
Zimanto society will be the coldest and coldest in a year.
At the hottest time, as two fixed points,
A general measuring system is designed.
They found that,
The melting point of ice is a constant,
This inspired later people to regard this as a fixed point. Huygens is at
1665
In this paper, it is suggested that the temperature of melting ice or boiling water should be used as the measured value.
Temperature reference point.