Glass potassium-rich

Durville F, Champagnon B, Duval E, Boulon G (1985) Ease spectroscopy of spinel microcrystallite in a Cr -doped silicate glass. J Phys Chem Solid 46 701—707 Erfurt G (2003) Infrared luminescence of Pb centres in potassium-rich feldspars. Phys Stat Sol (a) 200 429- 38... 

Numerous processes have been proposed for extracting potash from felspar, leucite, alunite, and other minerals rich in this substance, but the cost is so great that very few proposals yet made ofier promise of successful competition with the Stassfurt deposits. This is even the case with alunite, where mere calcination to 1000° drives off water and sulphuric acid, leaving water-soluble potassium sulphate, and alumina. Humphry Davy in his paper On Some Chemical Agencies of Electricity (1807), indicated in Cap. Ill, found that when water was electrolyzed in cavities contained in celestine, fluorspar, zeolite, lepidolite, basalt, vitreous lava, agate, or glass, the bases separated from the acid and accumulated about the cathode. It is therefore probable that if water with finely divided potash minerals in suspension were electrolyzed, the alkali would be separated in a convenient simple way. 

The diet of our pre-agricultural ancestors was rich in salt—not the salt now found on almost every table in small glass shakers, but potassium alkali salts, which are found in abundance in non-grain plant foods. These salts were eaten in their naturally occurring form. The salt we know today (and which some people love, to their detriment) is processed sodium chloride (NaCl), an addictive and overly used substance found in virtually every food choice in the Standard American Diet. Our SAD diet is also dangerously low in potassium alkali salts. Sodium chloride is acid-forming potassium salts are not. The combination of a sodium chloride excess with a potassium deficiency further contributes to the acid load on our systems. 

The sodium polyphosphate systems produce glasses very easily while it is difficult to make potassium glasses. The milky glassy masses of potassium metaphosphate compositions obtained by quenching the potassium melts are rich in potassium trimetaphosphate, though the phase diagram for the system contains none. Potassium cyclic triphosphate can be made thermally by dehydrating monopotassium orthophosphate with urea at temperatures less than 300 C,... 

Regarding the nature of the active surface composition of the bare MCP s, detailed investigations have been made by Panitz et al. (13) and Siddiqui (20). These show that, although the MCP faces are coated with an electrode material (Ni, Cr, nichrome), there is a thin (100 A) top surface layer rich in potassium (20) that has been transported up from the underlying glass. The inner surfaces of the channels also have a surface layer which is rich in alkali (primarily K) metals (oxides), Si, and SiC>2 (13, 20). These surface layers, in addition to the composition of the bulk glass (PbO + Si02, predominantly), determine the QDE (19). Improvements in the QDE may, however, be obtained by the use of photocathode materials deposited on the MCP surface, which will be discussed later in this paper. 

Several convenient calomel electrodes, such as the electrode illustrated in Figure 23-2a, arc available commercially. I he l -shapc body of the electrode is made of glass of dimensions shown in the diagram. The rich arm of the electrode contains a platinum electricnl contact, a small quantity of mercury mcrcury(l) chloride paste in saturated potassium chloride, and a few... 

In other civilizations (Mesopotamian, Greek), plant ash (potash) was used as a source of alkali. In contrast to natron (as may be expected), these plant ashes were rich in potassium. Mesopotamian sources reveal that plant ashes were used for glass making, and the Bible reports the use of borite ashes by the Old Testament fullers (Malachi 3 2). Ammonia obtained from stale urine was used in the textile industry in the Middle Ages. This historical introduction emphasizes the fact that many of the acids and alkalies used in the pre-scientific age were of biological origin. 

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