Cavendish experiment

Ibid., pp. 25-7, Alembic Club Reprint No. 3. H. Cavendish, Experiments... 

Reprint No. 3. H. Cavendish, "Experiments on Air, ref. (9), pp. 26-7, C W. Scheele, Sammtliche physische und chemische Werke, translated into German by Hermbstadt, Vol. 1, zweite unveranderte Auflage, Mayer and Muller, Berlin, 1891, pp. 186-7. 

Henry Cavendish, Experiments on air, Phil Trans.y 1784, as quoted in Henry M. Leicester and Herbert S. Klickstein, A Source Book in Chemistry 1400—1900 (New York McGraw-Hill, 1952), 152-153. 

In Morris Travers account of Ramsay s life and work, it was mentioned twice that Ramsay suggested Williams repeat the Cavendish experiment on air. It was the later repetition of Cavendish s experiment by others that resulted in the discovery of the noble gases ... 

Miss Katherine Williams, who worked for many years in the department on the chemistry of cooked fish, came first under Ramsay. It is said that he suggested that she should repeat the Cavendish experiment on air, but she chose something easier, the determination of the oxygen dissolved in water (p. 69). Later, when he and Miss K. Williams, at Bristol, were investigating an alleged allotropic form of nitrogen (Proc. Chem. Soc., 1886), he says that he suggested that she should... 

Henry Cavendish (1731-1810), well known in the history of the discovery of the elements (see Chapter 9 Hydrogen) is also well known within geophysics for the Cavendish experiment. In this, he determined, with simple means, the average density of the earth to be 5.45 times that of water, an astoundingly good result compared to the value of today, 5.5268. 

Cavendish, 1784] H. Cavendish. Experiments on Air, Philosophical Transactions of the Royal... 

Certainly, this is an extremely small value and is the reason why the determination of the gravitational constant with very high accuracy is a rather complicated experiment. During the last two hundred years there were many measurements of this constant, but still only three digits after decimal point are reliable. One can say that due to Cavendish s measurements it became possible to develop the theory of gravity and evaluate mass of the earth. In fact, determination of this mass was the main goal of this experiment. 

At the same time Rutherford conducted his experiments, three other chemists—Priestley, Cavendish, and Scheele—were also investigating fixed air gases, including nitrogen. However, Rutherford was given credit for discovering nitrogen. 

Lord Charles Cavendish might not have been wealthy, but he was a natural philosopher and experienced experimentalist. Indeed his research on heat, electricity, and magnetism earned him praise from Benjamin Franklin. Henry must have learned a lot from his father, because he, too, became a meticulous experimenter. Some of Henry s experiments in physics and most of his chemical experiments were performed while he was still living under his father s roof. 

In 1766 the Royal Society published Cavendish s Three Papers Containing Experiments on Factitious Air, describing his experiments with hydrogen, which is produced when metals are dissolved in acids. 

Hydrogen had previously been observed by Boyle and by Cavendish s contemporary Joseph Priestley. However, Cavendish is credited with the discovery of the gas because he was the first to perform experiments for the purpose of determining its properties. 

Cavendish s papers next described experiments with carbon dioxide, which he called fixed air. He studied its solubility in water and its efficacy in extinguishing flames. He concluded that when one part carbon dioxide was mixed with eight parts of ordinary air, candles would not burn. He also determined the density of carbon dioxide, finding that it was about 50 percent heavier than air. This result is astonishingly close to the modern value of 52 percent. 

I will pass over the other experiments described in these papers except to say that they were numerous. Cavendish s next paper on chemistry was of much greater interest. Published in 1784 under the title Experiments on Air, it described his discovery that water could be... 

Cavendish s most famous experiment, performed when he was nearly 70, is often described as weighing the Earth. This description is a little misleading, because what he was actually trying to do was determine the Earth s density. In order to do this, he needed to calculate the Earth s mass, though that wasn t his primary goal. 

Before Cavendish s experiment, no one knew the strength of the force of gravity. This might sound a little surprising at first, but not... 

Cavendish repeated the experiment 29 times and found that the Earth weighed 6 x 1021 (6 followed by 21 zeros) metric tons. The... 

Priestley wasn t wealthy like Boyle and Cavendish so he didn t have the leisure to spend as much time on scientific experiments as they did. However, by this time his fame had grown and he soon had a patron. William Petty, the second earl of Shelburne, admired Priestley s scientific work and offered him a post supervising the education of his two sons and collecting material on subjects under discussion in parliament. The salary was to be two and a half times what he was then earning, and Shelburne also provided his new... 

After Lavoisier had developed his theory of combustion, he was able to go a step further. First, with the assistance of the physicist Simon Laplace, he repeated Cavendish s experiment by burning hydrogen and oxygen in a closed vessel. Next, he passed steam over red-hot iron and found that it could be decomposed into hydrogen and oxygen again. Clearly, water was not an element. It was a compound formed from two gaseous elements. 

In spite of his love of solitude, Cavendish was not lacking in interest in the researches carried out by others. He presented young Humphry Davy with some platinum for his experiments, and went occasionally to the Royal Institution to see his brilliant experiments on the decomposition of the alkalies (6). Sir Humphry said later in his eulogy of Cavendish,... 

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