Alkalies, caustic fixed

From these he concluded that mild alkali = caustic alkali + fixed air. 

Bergman explains why he prefers the term air acid or aerial acid to the then usual name—fixed air. In the first place, because this is only one of several kinds of air which occur fixed, and in the second place, because it is at the same time a true acid and a constant constituent of the atmosphere. Fixed air, he says, is a true acid, because it possesses a distinctly acid taste it reddens litmus ( turnsol ) it attacks caustic fixed alkalies, rendering them mild a smaller quantity of this acid than of the stronger acids saturates these alkalies and renders them crystallizable and less soluble it makes the volatile alkali (ammonia) more fixed, less odorous and penetrating and causes it to crystallize when it just saturates quicklime, it deprives it of its solubility and acrimony and causes... 

Explain the terms volatile alkali, caustic alkali, and fixed... 

They give, with caustic fixed alkalies, a brown precipitate with ammonia, a similar one, soluble in the slightest excess with hydrochloric acid, or any soluble chloride, the white curdy precipitate of chloride of silver, insoluble in water and acids, but soluble in ammonia and with sulphuretted hydrogen, a dark brown, nearly black precipitate of sulphuret. Silver and all its compounds are very sensitive to sulphuretted hydrogen, which blackens them. Most of the compounds of oxide of silver are very soluble in ammonia and all the compounds of silver are darkened by the actjon of light, a property which has lately been applied to useful purposes in the Daguerreot3ipe, Calotype, and other photographic methods. Oxide of silver is reduced to the metallic state from its solutions by copper, zinc, and several other metals. When mercury is used, there is formed a heautiful arborescent crystallisation of an alloy of silver and mercury, called Arbor Dianae. 

Scottish chemist, physicist, and physician. Professor of chemistry at Glasgow. He clearly characterized carbon dioxide ( fixed air ) as the gas which makes caustic alkalies mild, and distinguished between magnesia and lime. He discovered the latent heats of fusion and vaporization, measured the specific heats of many substances, and invented an ice calorimeter. 

Dr. Black had noticed that when a carbonaceous substance is burned in air in such a manner that the fixed air can be absorbed in caustic alkali, a portion of the air remains. He had therefore assigned to his student,... 

Another very important point for the compositional story is Blacks recognition that fixed air plays the part of an acid in saturating the caustic alkali, and thus pneumatic chemistry joins with the major body of empirical chemical knowledge, that of neutral salts ... 

There are two serious problems associated with continuous tar distillation. Coal tar contains two types of components highly corrosive to ferrous metals. The ammonium salts, mainly ammonium chloride, associated with the entrained liquor remain in the tar after dehydration, tend to dissociate with the production of hydrochloric acid and cause rapid deterioration of any part of the plant in which these vapors and steam are present above 240°C. Condensers on the dehydration column and fractionation columns are also attacked. This form of corrosion is controlled by the addition of alkali (10% sodium carbonate solution or 40% caustic soda) to the cmde tar in an amount equivalent to the fixed ammonia content. 

The fixed caustic alkalies dissolve tin, and produce With it a compound in which the combination of this motal takes the character of a salt radical in this case water is decomposed and ite oxygen, is assimilated by the tin, whilst the hydrogen is given off., ... 

Black repeated these experiments, using chalk instead of magnesia, and showed in the same way, and with fairly accurate quantitative data, that quicklime differed from chalk in the same way that his calcined magnesia differed from mild magnesia. Although it was not possible to drive off the fixed air from alkalies, to form caustic alkalies, yet he recognized that a similar relation must exist between them, as between chalk and quicksilver. ... 

Almost colorless or yellowish, very refractive, oily liq characteristic smoky odor caustic, burning taste. d f not below L076, Begins to boil at about 203 and at least 90% by vol distills between 203-220. Does not solidify at —20. Sol In 150 200 parts water in glycerol, glacial acetic acid, fixed alkali hydroxide solns miscible with alcohol, chloroform, ether, oils. Incotnpai Acacia, albumin cupric, ferric, gold and silver salts oxidizers. 

Blackish-brown, viscous liquid heavier than water empy-reumatic odor and sharp taste. Slightly sol in water sol in ale, chloroform, ether, acetone, glacial acetic acid, fixed and volatile oils, and in solns of caustic alkalies. Principal con -stituents turpentine, resin, guaiacol, creosol, methylcreosol, phenol, phlorol. toluene, xylene, and other hydrocarbons. 

Crystals, mp 51.S, bp about 233. Appreciably volatile at 100° volatilizes in water vapors. Characteristic odor pungent, somewhat caustic taste, dj5 0.9699. nff 1.5227 njf 1.5204. One gram dissolves in about 1000 ml water, I ml alcohol, 0.7 ml chloroform, 1.5 ml ether, 1.7 ml olive oil at 25°. Sol in glacial acetic acid, oils, fixed alkali hydroxides. LDjj Orally in rats 980 mg/kg (Jenner). 

In Black s time only three major alkalis were recognized vegetable, marine, and volatile. Each of these was found in mild and caustic forms. Black s careful quantitative studies correctly convinced him that loss of fixed air is what converted mild alkalis to caustic alkalis. In modem terms, this can be summarized as follows ... 

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