Moist vapor

Hermetic and Neoplatonic tenets into their Islamic asceticism. Like all mystics, they strove for a personal experience of the divine, so it was natural that Jabir would be attracted to alchemy. Jabir developed a theory that became common to all subsequent alchemical texts. He said that all metals seemed to contain a balance of the four qualities that is, they are cold and dry externally, and hot and moist internally. This was due to the fact that they were formed in the earth by the union of a substance that he called sulphur or earthy smoke, and another, which he called mercury or moist vapor. Sulphur and mercury became a masculine and feminine polarity in alchemy. 

Aristotle s four-element theory was to exert a considerable influence on early laboratory chemistry, or alchemy (Chapter 2). The alchemists were also influenced by Aristotle s ideas on the formation of metals. He believed that metals and minerals were formed from exhalations. The two exhalations were a moist vaporous one, which was formed when the sun s rays fell on water, and a dry smoky one, which arose from the land. When these exhalations became imprisoned in the earth, they formed minerals or metals depending on which exhalation was... 

A steam or wet atmosphere can increase the cooling capacity of this arrangement because of the additional heat that can be handled by radiation directly from the heated moist vapor to the vessel walls (provided the vessel walls are kept cool by external means). Should there be a complete steam atmosphere, approximate calculations indicate that the magnitude of effective heat transfer would be on the order of six times that for air convection. From Fig. 54 it can be seen that the maximum ambient temperature would still exceed the reactor vessel temperature by about lOOOF. 

Psychrometrics. Psychrometrics is the branch of thermodynamics that deals specifically with moist air, a biaary mixture of dry air and water vapor. The properties of moist air are frequentiy presented on psychrometric charts such as that shown ia Figure 2 for the normal air conditioning range at atmospheric pressure. Similar charts exist for temperatures below 0°C and above 50°C as well as for other barometric pressures. AH mass properties ate related to the mass of the dry air. 

Saturation Temperature. The temperature at which the water vapor in moist air is in equiUbrium with Hquid water. 

Water vapor from moist product Sensible and latent heat gains People... 

Moist iodine vapor rapidly corrodes metals, including most stainless steels. The initial process is the formation of corrosion centers where small amounts of metal iodide are formed which deHquesce, and the corrosion then takes place electrochemically (41,42). Only titanium and molybdenum steels are unattacked by iodine (42,43). The corrosion of molten iodine has also been studied. 

White Phosphorus Oxidation. Emission of green light from the oxidation of elemental white phosphoms in moist air is one of the oldest recorded examples of chemiluminescence. Although the chemiluminescence is normally observed from sotid phosphoms, the reaction actually occurs primarily just above the surface with gas-phase phosphoms vapor. The reaction mechanism is not known, but careful spectral analyses of the reaction with water and deuterium oxide vapors indicate that the primary emitting species in the visible spectmm are excited states of (PO)2 and HPO or DPO. Ultraviolet emission from excited PO is also detected (196). 

In the presence of moist air, MnCl2 vapor decomposes into hydrochloric acid and manganese oxides. 

Leaks can be detected at once by ammonia odor unless there is already an appreciable amount of ammonia in the ak. Leaks can be exactiy located by using either moist phenolphthalein paper or an open bottie of hydrochloric acid. If a serious ammonia leak is discovered, a large column of water apphed through a fire hose having a spray nozzle can be used to absorb the vaporized ammonia. 

Health and Safety. Halosilane vapors react with moist air to produce the respective hydrohalogen acid mist. Federal standards have not set exposure to halosilanes, but it is generally beheved that there is no serious risk if vapor concentrations are maintained below a level that produces an irritating concentration of acid mist. The exposure threshold limit value (TLV) for HCl is 5 ppm, expressed as a ceiling limit. Because most people experience odor and irritation at or below 5 ppm, HCl is considered to have good warning properties. 

Step 1. Determine the total moist air flow to provide the dry air needed. Because the air is at atmospherie pressure, psyehrometrie eharts may be used to determine the amount of water vapor contained in the dry air (see Figures B-2 and B-3 in Appendix B). 

Ambient Wet-Bulb Temperature The temperature in degrees Fahrenheit to which air can be cooled, making it adiabatic to saturation by the addition of water vapor, in practical terms, the wet-bulb temperature is the temperature indicated by a thermometer, the bulb of which is kept moist by a wick and over which air is circulated. 

---