Was primarily based upon certain experiments on combustion and calcination, and in effect reduced the number of the alchemical principles, while setting up a new one, a principle of combustibility, named phlogiston (from (PXoyun-6s, burnt).
Metals on calcination gave calces from which the metals could.
He established as fundamental that combustion and calcination were attended by an increase of weight, and concluded, as did Jean Rey and John Mayow in the 17th century, that the increase was due to the combination of the metal with the air.
The phlogistic theory, which pervaded the chemical doctrine of this period, gave rise to continued study of the products of calcination and combustion; it thus happened that the knowledge of oxides and oxidation products was considerably developed.
The calcination is preferably effected in mechanical roasters, it being especially necessary to agitate the ore continually, otherwise it cakes.
The carbonic acid gas injected into the highly limed juice in the saturators is made by the calcination of limestone in a kiln provided with three cleaning doors, so arranged as to allow the lime to be removed simultaneously from them every six hours.
The phlogistic theory of the processes of calcination and combustion necessitated the view that many acids, such as those produced by combustion, e.g.
Three stages in the process are to be distinguished: (i.) calcination, to convert all the metals, except gold and silver, into oxides, which are unacted upon by chlorine; (ii.) chlorinating the gold and lixiviating the product; (iii.) precipitating the gold.
The calcination, or roasting, is conducted at a low temperature in some form of reverberatory furnace.
Sulphuretted ores are smelted, either with or without a preliminary calcination, with metallic iron; calcined ores may be smelted with carbon (coal).
The reactions are strictly analogous to those which occur in the smelting of galena (see Lead), the carbon reducing any oxide, either present originally in the ore or produced in the calcination, and the iron combining with the sulphur of the bismuthite.
A certain amount of bismuth sulphate is always formed during the calcination; this is subsequently reduced to the sulphide and ultimately to the metal in the fusion.
Calcination in reverberatory furnaces and a subsequent smelting in the same type of furnace with the addition of about 3% of coal, lime, soda and fluorspar, has been adopted for treating the Bolivian ores, which generally contain the sulphides of bismuth, copper, iron, antimony, lead and a little silver.
The study of calcination and combustion during the 17th and 18th centuries culminated in the discovery that air consists chiefly of a mixture of two gases, oxygen and nitrogen.
Potassium carbonate, K 2 CO 3, popularly known as "potashes," was originally obtained in countries where wood was cheap by lixiviating wood ashes in wooden tubs, evaporating the solution to dryness in iron pots and calcining the residue; in more recent practice the calcination is carried out in reverberatory furnaces.
This lime is charged in the form of common quicklime, CaO, resulting from the calcination of a pure limestone, CaCO 3, which should be as free as possible from silica.
Jeweller's rouge for polishing plate is a fine red iron oxide prepared by calcination from ferrous sulphate (green vitriol) .
If plaster of Paris is to be made, calcination is carried out at about 204° C. (= 400° F.); at this temperature, gypsum, CaSO 4.2H 2 O, loses three-quarters of its combined water and becomes 2CaSO 4 H 2 O.
Both processes are inferior in economy to calcination in rotatory kilns, a process which may be regarded as the method of the present and the immediate future.
Then, perceiving that in combustion and the calcination of metals only a portion of a given volume of common air was used up, he concluded that Priestley's new air, air eminemment pur, was what was absorbed by burning phosphorus, &c., "non-vital air," azote, or nitrogen remaining behind.
This is effected by calcination or roasting.
The " English process " is made up of the following operations: (i) calcination; (2) smelting in reverberatory furnaces to form the matte; (3) roasting the matte; and (4) subsequent smelting in reverberatory furnaces to fineor white-metal; (5) treating the fine-metal in reverberatory furnaces to coarseor blistercopper, either with or without previous calcination; (6) refining of the coarse-copper.
It is made up of the following operations: (z) calcination, (2) smelting in blast-furnaces to form the matte, (3) roasting the matte, (4) smelting in blast-furnaces with coke and fluxes to " black- " or " coarse-metal," (5) refining the coarse-metal.
It may also be accomplished by calcination with ferrous sulphate, or other easily decomposable sulphates, such as aluminium sulphate.
Calcination is only advisable for ores which contain relatively much iron pyrites and little copper pyrites.
Also, however slowly the calcination may be conducted, there is always more or less copper sulphide left unchanged, and some copper oxide formed.
Calcination with ferrous sulphate converts all the copper sulphide into sulphate.
The conversion of the sulphide into oxide is adopted where the Douglas-Hunt process is employed, or where hydrochloric or sulphuric acids are cheap. The calcination is effected in reverberatory furnaces, or in muffle furnaces, if the sulphur is to be recovered.
The quicklime as quarried from the bluffs slakes perfectly, and with sand makes a fairly good mortar, without calcination or other previous preparation.