Calcination of metals

Lavoisier now turned his attention to the calcination of metals, and particularly the calcination of tin. Boyle supposed that the increase in weight which accompanies the calcination of a metal is due to the fixation of "matter of fire" by the calcining metal Rey... 

Priestley also observed that lime-water never became turbid by the calcination of metals over it, and that when this process was made in quicksilver, the air was diminished only one-fifth and upon water being admitted to it, no more was absorbed (12). He stated that this air in which candles, or brimstone, had burned out. .. is rather lighter than common air (12). Thus Priestley recognized, even at this early date, some of the most important properties of the gas now known as nitrogen. 

That the calcination of metals when they are contained in a portion of air confined in a glass bell jar does not take place with quite the same facility as in free air. 

In the course of the memoirs that I have communicated to the Academy, I have passed in review the principal phenomena of chemistry. I have insisted upon those which accompany combustion, the calcination of metals, and, in general, all the operations where there is absorption and fixation of air. I have deduced all the explanations from a simple principle. This is that the air pure, the vital air, is composed of a simple principle which is peculiar to it, which forms the base of it, and which I have called prin-cipe oxygine —combined with the material of fire or heat. This principle once admitted, the chief difficulties of chemistry have appeared to vanish and be dissipated, and all phenomena have been explained with astonishing simplicity. 

In the sixteenth century it was already known to alchemists that the calcination of metals is accompanied by an increase in weight, and in the seventeenth it had been noted that the air, from its behaviour, must contain a principle analogous to that in nitre. 

Porosity within a particle is a manifestation of the shape of a particle. Fractal particles will have internal porosity as a result of their shapes. Fractal particles with low fractal dimensions (i.e., <2.0) will have a broad pore size distribution, where the largest pore approaches the size of the aggregate. Fractal particles with large fractal dimensions (i.e., >2.0) will have narrower pore size distributions with most of the porosity occurring at a size much smaller than that of the aggregate. Calcination of metal salt particles or metal hydroxides to produce oxides is another common method to produce internal porosity. In the gas evolution that takes place in transformation to the oxide, pores are opened up in the particle structure. The opening of pores in a hydrous alumina powder can increase its surface area from 0.5 m /gm (its external area) to 450 mVgm (its internal pore area). 

The second, experimental part of the Opuscules consists of three genres of experiments, accurately reflecting Lavoisier s work during the previous year—a review of the principal experiments involved in the Black-Meyer controversy, the calcination of metals, and the combustion of phosphorus and sulphur. In the first three chapters, Lavoisier repeated the experiments related to the main controversy to prove that the same elastic fluid was involved in them. He maintained a quantitative thread by tracking the specific gravity of the air produced in each experiment. In the plan and execution of these experiments, he assumed that a chemical substance was uniquely defined by its composition (constituents and... 

The composite nature of water held a significant place in Lavoisier s oxygen theory because it accounted for the inflammable air and the vital air produced in the humid calcination of metals. In the calcination of metals using vitriolic acid, Lavoisier knew that the vital air did not come from the vitriolic acid, since the operation did not produce sulphur or sulphurous acid. Water was the only possible source. Lavoisier worked hard, therefore, to prove the compound nature of water, which he presented to the Academy on November 12, 1783. The importance he attached to this project becomes evident, as Daumas and Duveen pointed out, in his careful preparation for a large-scale demonstration. The public enthusiasm for ballooning had induced the Academy to appoint a... 

There is an extensive literature devoted to the preparation of oxide and mixed-oxide catalysts. These compounds are often derived from hydroxides, though alternative processes are available, e.g., calcination of metals, oxalates etc. Some of the studies referred to above were undertaken to add to the understanding of the textural changes which accompany water removal during the preparation of catalytically-active phases of technological importance. Heating of mixed hydroxides, prepared by concurrent precipitation, yields spinels and other specific phases, including solid solutions, at lower temperatures than is possible with less-intimate mixtures. The... 

The crucial event in Lavoisier s career was his realization that air (which nearly everyone believed to be a simple substance defined by its physical, rather than by any chemical, properties) must play a part in chemical transformations - most dramatically those observed in ordinary combustion, the roasting (calcining) of metals, and the reduction of ores or cakes . ... 

So much for the heating of liquids. Frequently, however, it was necessary to heat substances to higher temperatures. For instance, in the calcination of metals— that is, the "burning" of them to form oxides—very strong heat is required. Similarly in the reverse process— the smelling, or "reduction" of ores to the metal— high temperatures are required. For these temperatures, a crucible was necessary. 

Calcination of metals is analogous to the burning of phosphorus and sulphur, and involves a combination with air. ... 

I found that air is a mixture of two substances - to the purer y part, which is used in respiration and in calcinations of metals, we give the name oxygen and the residue we will call mofette. I later decided to call the residue azote, from the Greek term meaning without life . In 1790, Jean Antoine Chaptal gave it its modern... 

There are already traces of the influence of the new chemistry in the first Critique, second edition (1787), where Kant adds a physico-chemical example (state transition from fluidity to solidity) to the transcendental deduction (B162) though he still mentions Stahl s theory of the calcination of metals (Bxiii). Stahl s phlogiston theory is still in full force in the Danziger Physik of 1785, e.g. (29 163). 

Of lime or yulCXLIME, sonuctineH to the more modern meaning of the powdec or friritile substance obtained by the calcination of metals or minorala. 

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