Air fixed

RVP is a vapor pressure measurement at a fixed air/Hquid ratio of 4 and a temperature of 38°C. It is measured under conditions of water saturation. For samples which contain water-soluble components such as alcohols, ASTM D4953 is used. 

For a kitchen hood with a fixed air curtain, good results are possible if the exhaust flow rate is large enough to exhaust the large amounts of con taminants and induced air from the oven. The circular jet around a wdtl-ing or soldering point is usually too cumbersome to use when working at more than one spot. 

Fixed air terminal device A component that has fixed (nonadjustable) parts. 

CO2 ( fixed air ), prepared by Joseph Black (aged 24-26), was the first gas other than air to be characterized (i) chalk when heated lost weight and evolved CO2 (genesis of quantitative gravimetric analysis), and (ii) action of acids on carbonates liberates CO2. 

Fitze,/. (Textiles) hank, skein, fix, a. fixed fast smart. — fixe Luft, fixed air (old name for carbon dioxide). 

Calculate the new Ga, assuming that L is the important value known. If on the other hand, it is desired to determine just how much cooling can be obtained, then for a fixed air rate, calculate the L that can be accommodated. 

There are many other examples of changes in which a solid passes into a liquid, or a liquid into a gas, with absorption of heat at constant temperature. The constant temperature may be called the transition temperature the heat absorbed is called the latent heat of the transition. The latter name is due to Joseph Black, the discoverer of the phenomenon (1757) he appears to have regarded the heat as existing latent in the body in some sort of chemical combination, just as fixed air exists latent in chalk. In both cases the entity has lost its properties by chemical combination, but may be set free again in a suitable way. 

Yet thermal conductivity alone is not sufficient for the characterization of gaseous mixtures. Given a fixed air ratio and temperature, thermal conductivity of flue gases, resulting from the combustion of different fuels, does not vary by more than 1%. A changing air ratio has a smaller effect than a small rise in the flue gas temperature. Therefore the thermal conductivity alone is not suitable as reference value. Further information is required to identify fuel gases. 

At the same time Rutherford conducted his experiments, three other chemists—Priestley, Cavendish, and Scheele—were also investigating fixed air gases, including nitrogen. However, Rutherford was given credit for discovering nitrogen. 

Cavendish s papers next described experiments with carbon dioxide, which he called fixed air. He studied its solubility in water and its efficacy in extinguishing flames. He concluded that when one part carbon dioxide was mixed with eight parts of ordinary air, candles would not burn. He also determined the density of carbon dioxide, finding that it was about 50 percent heavier than air. This result is astonishingly close to the modern value of 52 percent. 

It was around this time that Priestley discovered soda water. Fixed air (carbon dioxide) had long been known to chemists, and Priestley had experimented with it a little. One day he had the idea of trying to dissolve the carbon dioxide in water. He succeeded and found that the water fizzed. Priestley gave some of the soda water to friends and then went on to other kinds of research. Some years later the British Navy expressed interest in the use of Priestley s sparkling water as a remedy for scurvy, but naturally it was unsuccessful. However, soda water quickly became popular in other circles, even earning praise from Lord Byron, who wrote the following stanza on the back of the manuscript of his poem Don Juan ... 

In October 1772 Lavoisier performed some experiments using a large burning lens owned by the Academy of Sciences. He found that when litharge (an oxide of lead) was heated with charcoal, large quantities of air were released. Of course it wasn t air at all—it was carbon dioxide. At the time, Lavoisier was unaware that carbon dioxide—or fixed air as it was then called—has properties very different from ordinary air. He was also unaware that Priestley had experimented with numerous different airs and had shown that atmospheric air has more than one component. Lavoisier also performed experiments that showed that sulfur and phosphorus also gain weight when they are burned. Marie Anne wrote up the results... 

Lavoisier concluded that ordinary atmospheric air was responsible for combustion and for the weight gain of the substances that were burned. At the time, he was unaware of the experimental work that had been done, most notably by Priestley, on the different kinds of airs that were the products of chemical reactions. Nor did he know that it had been demonstrated as long ago as 1756, by the Scottish chemist Joseph Black, that fixed air had properties that were very different from those of the air that constituted the atmosphere. 

Lavoisier was aware of his ignorance, however, and in 1773 he began an intensive study of the history of chemistry, paying special attention to experiments with the different airs and repeating many of these experiments with new safeguards. However, this only led him to a new error. He now became convinced that fixed air, or carbon dioxide, was responsible for combustion. 

In 1787 Guyton de Morveau, Lavoisier, Berthollet, and Fourcroy introduced in their Methode de nomenclature chimique the terms carbone, for the element carbon, instead of charbon (charcoal) and acide carbonique (carbon dioxide) instead of air fixe ( fixed air ). 

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. 

Not long after this meeting with Benjamin Franklin, Priestley accepted a pastorate at Leeds. Since the parsonage happened to be located next door to the Jakes and Nell Brewery, the Reverend Mr. Priestley had a convenient source of fixed air for his experiments. He soon discovered the pleasant taste of water charged with this gas, and recommended the refreshing beverage to his friends. Dr. William Brown-rigg had previously made the same discovery (22, 47). 

Take thou this earth, take from it the fixed air (53).a... 

The specific gravity of this air was found to differ very little from that of common air, of the two it seemed rather lighter. It extinguished flame, rendered common air unfit for making bodies burn, in the same manner as fixed air, but in a less degree. . . (II). 

Priestley had nearly anticipated Rutherford and indeed, he speculated on the nature of the residual gas, left after combustion and absorption of the fixed air produced (13). Although Rutherford referred in his thesis to Priestley s experiments on the effect of vegetation on the atmosphere, he was evidently unfamiliar with those on nitrogen (14, 15). 

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,... 

The dissertation begins with an appropriate quotation from Lucretius and a review of the researches of Black and of Cavendish on fixed air. Rutherford then described his own experiments in which he had found that a mouse, left in a confined volume of atmospheric air until it died, had consumed Via of the air, and that treatment of the remaining air with alkali had caused it to lose one-eleventh of its volume. He found... 

In 1783 he published an annotated translation of Torbem Bergman s Sciagraphia regni mineralis, and in the following year he communicated to the Philosophical Transactions his Experiments and observations on terra ponderosa (barium carbonate, or witherite) (96). He stated that the specimen he examined came from a lead mine at Alston Moor, on the Pennines of Cumberland. Although he at first mistook it for heavy spar (barite) he soon found it to be a compound of heavy earth (barium oxide) and fixed air (carbon dioxide) (97). 

Black decided that the gas given off in the reaction between magnesia alba and acid was similar to one described by van Hel-mont. He coined the term fixed air to indicate that this gas was fixed or trapped in magnesia alba. Black also recognized that fixed air was the same gas produced in respiration, combustion, and fermentation. Today, we know Black s fixed air was car-... 

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