Davy, Sir Humphrey

Wedgwood, Thomas (son of the famous potter) and Davy, Sir Humphrey, in 1802, reported in a communication to the Royal Institution in London a photographic process using AgCl to record an image. 

Davy, Sir Humphrey. (1824). On the corrosion of copper sheathing on ships by sea... 

Gr. barys, heavy) Baryta was distinguished from lime by Scheele in 1774 the element was discovered by Sir Humphrey Davy in 1808. 

It is not certain whether Sir Humphrey Davy (Fig. 1-7) knew of these considerations. He accepted a commission from the Admiralty for the protection of copper-clad wooden ships, which had been introduced in 1761. During his numerous laboratory experiments, he discovered the cathodic protection of copper by zinc or iron [3]. Davy had already put forward the hypothesis in 1812 that chemical and electrical changes are identical or at least arise from the same material property. He believed that chemical reaction forces could be reduced or increased by altering the electric state of the material. Materials can combine only if they have different electric charges. If an originally positive material can be artificially negatively... 

Also in 1815, but before Davy presented his first lamp to the public, George Stephenson (one of the pioneers in the development of the steam locomotive) quite independently was also working on a safe miner s lamp. He discovered during his experiments that flame produced by a particular gas at a given concentration will not pass through a tube smaller than a certain diameter. While most people have heard of Davy s lamp (it seems that Sir Humphrey received all the credit), it was actually Stephenson s discov-... 

In recent years it has been regarded as somewhat passe to refer to Sir Humphrey Davy in a text on cathodic protection. However, his role in the application of cathodic protection should not be ignored. In 1824 Davy presented a series of papers to the Royal Society in London in which he described how zinc and iron anodes could be used to prevent the corrosion of copper sheathing on the wooden hulls of British naval vessels. His paper shows a considerable intuitive awareness of what are now accepted as the principles of cathodic protection. Several practical tests were made on vessels in harbour and on sea-going ships, including the effect of various current densities on the level of protection of the copper. Davy also considered the use of an impressed current device based on a battery, but did not consider the method to be practicable. 

Gas hydrates are a special form of clathrates. Here water is the host molecule. The first gas hydrate (with chlorine) was described in 1818 by Sir Humphrey Davy. Naturally-occurring gas hydrates in Siberia are methane hydrates. 

Boron itself was first produced in 1808 by Sir Humphrey Davy, who carried out the electrolysis of molten boric acid. The reduction of boric acid by potassium was used as a preparative method by Gay-Lussac and Thenard in 1808, and reduction of B203 by magnesium was the method used by Moissan in 1895. 

Before the availability of artificial fertilizers in the mid-19th century, farms were traditionally organic, with recycling of animal waste, and perhaps with the application of lime on acid soils. Agricultural chemical analysis may have begun with Carl Wilhelm Scheele (1742-1786), the Swedish pharmacist who isolated citric acid from lemons and gooseberries and malic acid from apples. In France, Nicolas Theodore de Saussure (1767-1845) studied the mineral composition of plant ash, and in Britain, Sir Humphrey Davy... 

Barium was discovered in 1808 by Sir Humphrey Davy. Its abundance in the earth s crust is about 0.0425% (425 mg/kg). The element also is found in sea water at trace concentration, 13 J,g/L. It occurs in the minerals barite or heavy spar (as sulfate) and witherite (as carbonate). 

The element was discovered in 1808 independently by Sir Humphrey Davy and also by GayLussac and Thenard. Boron does not occur in nature in free elemental form but is found in many borate ores. The principal borate minerals are as follows ... 

Basilus Valentinus of Italy was first to isolate the acid and reported it under the name spiritus sabs in the fifteenth century. Glauber prepared this acid by the reaction of sulfuric acid with common salt in 1648. Lavoisier proposed the name muriatic acid in 1789 after muriate, the term referring to a chlorine-containing inorganic substance. Sir Humphrey Davy proved the gas was composed of only hydrogen and chlorine in 1810. Subsequently, the gas was named hydrogen chloride. 

Nitrous oxide (N20) was first prepared by Priestly in 1772. Its anaesthetic properties were described by Sir Humphrey Davy in 1800 and it was first used in clinical practice by Colton and Wells in 1844. Physical characteristics... 

---