Supporters of combustion

Ironically, the three principles that had guided Lavoisier s creative researches and organized Part I of the TraitS failed to become a permanent part of chemistry. The caloric model of gases, oxygen as sole supporter of combustion, and oxygen as the principle of acidity, were all quickly abandoned by nineteenth century chemists, chiefly through the discoveries of Humphry Davy. 

Sulphurous acid gas is absorhed by water and hence, in order to examine its properties in that state, it must he collected over moreury. It is colorless and transparent, having a peculiar irritating odor, and cannot be respired. It is neither combustible, nor a supporter of combustion. It possesses bleaching properties, owing to wliich it is used in the arts to whiten straw bonnets, com, silk, sponges, and other substances if a red rose be expesed to the flame of burning sulphur, it becomes completely white. 

Air, which is a mixture, and not a compound, of nitrogen, oxygen, carbon dioxide, ammonia, water-vapour, and the gases of the helium group, is a supporter of combustion,... 

Add a part of the solution to 2 cc. of NH4OH and notice that there is effervescence, the escaping gas being non-combustible and a non-supporter of combustion (nitrogen). (See Preparation 19.)... 

The calculation of the flame temperature for a combustible gas like hydrogen, carbon monoxide, or methane at first sight appears to be a simple problem since the apparently necessary data are only the heat of combustion and the specific heats of the products. Such calculations always yield very high results much above those recorded by direct experimental measurements. The discrepancy is probably due to a combination of several causes. On account of the temperature of the flame the products are partially dissociated,1 so that combustion is not complete m the flame. The specific heat of gases increases with rise m temperature, so that the value obtained at the ordinary temperature for the specific heat is too low. In addition to these two causes, another contributory factor is the loss of heat by radiation, which may be very considerable even m nou-lummous flames, whilst the general presence of an excess of the supporter of combustion and the non-instantaneous character of the combustion also detract from the accuracy of the calculation.2... 

Combustion properties of interest in cellular plastics and elastomers include ease of ignition (ignitibility), support of combustion (oxygen index), relative extent and time of burning, surface flammability, flame read, smoke evolution properties, and rate of beat release. The following test methods are either concerned solely with cellular plastics, m are used for both cellular and solid plastics. 

It is neither combustible nor a supporter of combustion. Burning objects get extinguished in carbon-dioxide gas. 

It is presumed that students know that air contains oxygen and nitrogen. They also know that oxygen is a supporter of combustion and that a burning candle goes out in nitrogen. 

When non-combustible components are present in a mixture, their presence in the vapor space does not contribute to the support of combustion at the flash point. In such cases, Mv is calculated as the mean molecular weight of only the flammable components present in the vapor phase. This approach of course ignores the likely effects of different noncombustible components on mixture flash points but nevertheless provides an effective model. 

All these eighteenth century investigators expressed their views on the action of air and combustion in terms of the phlogistic theory of Becher and Stahl, and it remained for Antoine-Laurent Lavoisier, the French savant, who fell a victim to the guillotine in 1794, to free them from this incubus and to develop the new theory wherein oxygen was assigned its proper role as a constituent of air and a supporter of combustion. 

The process of respiration is very similar to combustion, and as oxygen gas is the beat supporter of combustion, so, in the diluted form in which it exists in atxnospheric air, it is not only the best, but tbe only supporter of animal respiration. (Sc carbon dioxide.)... 

Properties.—A colorless, odorless, tasteless, non-combustible gas not a supporter of combustion very sparingly soluble in water. 

Chemical.—It is decomposed by a red heat and by the continuous passage of electric simrks. It is not combustible, but is, after oxygen, the best supporter of combustion known. 

The process of combustion consists essentially, in ordinary oases, in the combination of the combustible with oxygen by a chemical action intense enough to develop light and heat. Of course unless air is present, or some other supporter of combustion, this process can not gn on. Now the Greek fire, so far os is noAv known, contained witliin itself no substance... 

Ate light as well as heat. Gases are said to he supporters of combustion, when combustible substances will unite with them, or with some of their constituents, the union being attended with the appearance of heat and light. The distinction between combustible substances and supporters of combustion is, however, one of mere convenience. The actionitaking place between the two substances, one is as much a party to it as the other. A jet of air burns in an atmosphere of coal-gas as readily as a jet of coal-gas burns in air. 

Chemical.—Hydrochlorie acid is neither combustible nor a supporter of combustion, although certain elements, such as K and i(a,burn in it. It forms white clouds on contact with moist air. 

Chemical.—Sulfur dioxid is neither combustible nor a supporter of combustion. Heated with H it is decomposed SOa+2Ht = S + 2HaO. With nascent hydrogen, HaS is formed 80a + SHa = HaS + 2HaO. 

A measnre of a system for the extent of its support of combustion (ASTM D-635AJL E-94 tests). 

Faraday in his diary says Ampere, Clement, and Desormes came this morning [23 November 1813] to show Sir H. Davy a new substance, discovered, about two years ago, by M. Courtois, saltpetre manufacturer. The process by which it is obtained is not yet publicly known. It is said to be procured from a very common substance, and in considerable quantities . Very little information would seem to have been given to Davy, who at first (says Faraday) thought it was a compound of chlorine and an unknown body, although the entry for the same day says Davy now thinks it contains no chlorine . On I December, Faraday says, Davy had made many experiments on it with his travelling apparatus M. Clement has lately read a paper on it... in which he says it is procured from the ashes of sea-weeds by lixiviation and treatment with sulphuric acid. He conceives it to be a new supporter of combustion. On 3 December, Davy was working on it in Chevreul s laboratory and on ii December he concluded that as yet it must be considered as a simple body . 

Whereas most FRs act by interfering with one of the three supports of combustion heat, fuel and oxygen, MC acts on all three. In the initial stage it creates a heat sink by endothermic reactions and subsequent decomposition of melamine vapours. It provides only about 40% of the heat of combustion of hydrocarbons, and the combustion then generates nitrogen, which acts as an inert diluent. 

Most of the English text-books of the early nineteenth century pointed out the weaknesses in Lavoisier s caloric theory of combustion. Thomson, who divided the elements then knovrn into combustibles, supporters of combustion, and incombustibles, removed the objectionable name phlogiston from the theories of Hutton (see p. 628), Richter, and Gren, and proposed a theory that oxygen gas is a compound of oxygen base and caloric, and a combustible a compound of a specific base and light. 

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