Sharp waters

The distillate here described as obtained from the retort at redness would be a mixture of sulphuric and nitric acids, and by the addition of the ammonium chloride, hydrochloric acid. The solvent action of this acute or sharp water makes much more comprehensible the chemistry of many processes described, than if we assumed that the vegetable acids were the only ones used. It is probable that this is by no means Geber s invention, but he is perhaps the first who describes the preparation so clearly and comprehensibly. 

Abstract A concept of amphiphilicity in application to monomer units of water-soluble polymers is presented. Molecular simulation and experimental studies of polymers consisting of amphiphilic monomers units are reviewed. Those polymers reveal unusual conformational behavior in aqueous solutions forming nanostructures of nonspherical shape. Self-association of amphiphilic thermosensitive polymers in water solutions is discussed. Possibilities for the use of thermosensitive copolymers as catalysts are described. The sharp water-organic boundaries formed by polymer associates in water solutions are shown to be a prospective medium for catalysis owing to adsorption of interfacially active substrates at the interface. 

This approach might seem to be rather crude however, it should be noted that recent molecular simulations of simple electrolytes interfaces [28] show that the variation of the electrolyte concentrations is about as steep as the variation of water density at the interface. Therefore, if one assumes a sharp water/air interface, one can also assume step distributions for the ions of the electrolyte. 

Explicit expressions for the additional interactions between ions and interfaces, A W,(x), allow us to calculate the distribution of ions c,(x) (for a sharp water/air interface) eqs 10a and 10b, for the appropriate boundary conditions... 

Chemically bound water is most reasonably defined as including that present in interlayer spaces, or more firmly bound, but not that present in pores larger than interlayer spaces. As will be seen in Chapter 8, the distinction between interlayer space and micropores is not sharp water adsorbed on surfaces of pores further blurs the definition. From the experimental standpoint, the determination is complicated by the fact that the amount of water retained at a given RH depends on the previous drying history of the sample and on the rate at which water is removed. An approximate estimate is obtained by equilibrating a sample, not previously dried below saturation, with an atmosphere of 11% RH (F12,F13,F14). Saturated aqueous LiCl HjO gives the required RH (partial pressure of water vapour = 2,7 torr at 25°C). To achieve apparent equilibrium in a reasonable time (several days), the sample must be crushed and the system evacuated the salt solution should be stirred, at least intermittently. Young and Hansen (Y5) found the composition of the C-S-H in C3S paste thus... 

Fig. 4. Cross-section view of the nozzle region and ink channels of an inkjet print head, showing the sharp water concentration gradient that evolves at an inactive, exposed nozzle.

For TIR fluorescence spectroscopy on water/oil interfaces, the choice of a probe molecule is of primary importance. For example, the penetration depth (dp) of an incident evanescent wave at a 1,2-dichloroethane (DCE, refractive index (n) n = 1.44)/water (m2 = 1.33)interface is calculated to be 94nm on the basisofEquation(13),whereX = 580 nm and 0 = 80°. It has been reported that the thickness of a sharp water/oil interface represented by water/DCE is 1 nm [9], so that dp of the incident evanescent wave is thicker than the thickness of the interfacial layer, and the fluorescence characteristics of a probe molecule in the bulk phase are superimposed, more or less, on those at the interface [2]. Therefore, a probe molecule should be highly surface-active and adsorb on the interface, so as to exclude fluorescence of the probe molecule from the bulk phase. In the present experiments, we employed xanthene dyes as fluorescence probes throughout... 

Dynamic fluorescence anisotropy is based on rotational reorientation of the excited dipole of a probe molecule, and its correlation time(s) should depend on local environments around the molecule. For a dye molecule in an isotropic medium, three-dimensional rotational reorientation of the excited dipole takes place freely [10]. At a water/oil interface, on the other hand, the out-of-plane motion of a probe molecule should be frozen when the dye is adsorbed on a sharp water/oil interface (i.e., two-dimensional in respect to the molecular size of a probe), while such a motion will be allowed for a relatively thick water/oil interface (i.e., three-dimensional) [11,12]. Thus, by observing rotational freedom of a dye molecule (i.e., excited dipole), one can discuss the thickness of a water/oil interface the correlation time(s) provides information about the chemi-cal/physical characteristics of the interface, including the dynamical behavioiu of the interfacial structure. Dynamic fluorescence anisotropy measurements are thus expected... 

Typically, a sharp water peak is obtained in approximately 2 min. The water peak is always well separated from an earlier injection peak that is due to the sample matrix. Under favorable conditions a very short column (length 2.5 cm) can be used and a water peak obtained in as little as 20 s [17]. 

At 180°C the salt decomposed to give the amide and water with a sharp water loss (observed in Figure 2) ... 

Take e cjual parts of calcined a/ Q/// (sodium carbonate) and unsla Iced lime and pour over them A times tbeir amount of water and leave it for 5 days, filter tbe mixture and again add al C2ili and ime to tbe extent of one-fou rtb of tbe filtered solution. b)o this 7 times. Your it into half (tbe volume) of dissolved sal ammoniac. Th en Iceep it for verily it is tbe strongest sharp water. t will dissolve Jalcj (mica) immediately. 

Notably systematic, al-Razi relied on observed and verifiable facts, and he almost entirely avoided mysticism. For instance the following recipe for sharp waters, a strong caustic solution, is very clear, and it could easily be followed in any general chemistry laboratory today. 

Rhases adopted the sulphur-mercury theory of metals, and also believed in the possibility of transmutation, but it is clear that he was a very knowledgeable practical chemist. He described the preparation of caustic alkalis by treating sodium or potassium carbonates (obtained by leaching ashes) with slaked lime. Our word alkali comes from the Arabic al-Quili, meaning calcined ashes. The caustic alkalis, along with acidic solutions such as vinegar, sour milk and lemon juice, were known as sharp waters, 2mA were widely used as solvents. Rhases drew up... 

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