Colouration water hardness

Ca and Mg in water (water hardness) Ca determination Add 2 cm 3 of NaOH solution (0.1 mol dm 3) to 50 cm3 of sample and titrate with EDTA using murexide indicator (table 5.8). Mg determination Destroy murexide colour with 1 cm3 concentrated HQ add 3 cm3 of NH3—NH4C1 buffer and titrate with EDTA using eriochrome black T. 

Elixir is the Ferment, the Leaven, the Dough, which is produced from Water. It is a Coloured Water, mingled with Bodies it is also the White Stone, Olitet and Powder, for it is all one thing. It is also called the Treasure, First Matter this is an imperfect Elixir. When it is perfect and ready, it is then truly a treasure. Lacinius says Elixir is made of three things-Sol, Luna, and Mercury. But it must be of a moderate quality, between hard and soft — softer and more subtle than Mercury. Otherwise the gold that is made of it cannot be hammered. Out of the Elixir comes Azoth, and is the first part of the work. Therefore is the Elixir of two kinds-white and red. When it is red, one adds the ferment to it, and it is multiplied. Or ... 

Note on the laboratory preparation of monoethylaniline. Although the laboratory preparation of monomethyl- or monoethyl-aniline is hardly worth whUe, the following experimental details may be useful to those who wish to prepare pure monoethylaniline directly from amline. In a flask, fitted with a double surface reflux condenser, place 50 g. (49 ml.) of aniline and 65 g. of ethyl bromide, and boU gently for 2 hours or until the mixture has almost entirely sohdified. Dissolve it in water and boil off the small quantity of unreacted ethyl bromide. Render the mixture alkaUne with concentrated sodium hydroxide solution, extract the precipitated bases with three 50 ml. portions of ether, and distil off the ether. The residual oil contains anihne, mono- and di-ethylaniline. Dissolve it in excess of dilute hydrochloric acid (say, 100 ml. of concentrated acid and 400 ml. of water), cool in ice, and add with stirring a solution of 37 g. of sodium nitrite in 100 ml. of water do not allow the temperature to rise above 10°. Tnis leads to the formation of a solution of phenyl diazonium chloride, of N-nitrosoethylaniline and of p-nitrosodiethylaniline. The nitrosoethylaniline separates as a dark coloured oil. Extract the oil with ether, distil off the ether, and reduce the nitrosoamine with tin and hydrochloric acid (see above). The yield of ethylaniline is 20 g. 

Compared with the phenolics and polyesters the resins have better heat resistance, better chemical resistance, particularly to alkalis, greater hardness and better water resistance. In these respects they are similar to, and often slightly superior to, the epoxide resins. Unlike the epoxides they have a poor adhesion to wood and metal, this being somewhat improved by incorporating plasticisers such as poly(vinyl acetate) and poly(vinyl formal) but with a consequent reduction in chemical resistance. The cured resins are black in colour. 

Substances such as brass, wood, sea water, and detergent formulations are mixtures of chemicals. Two samples of brass may differ in composition, colour and density. Different pieces of wood of the same species may differ in hardness and colour. One sample of sea water may contain more salt and different proportions of trace compounds than another. Detergent formulations differ... 

The acids are mixed in a flask (500 c.c.), and the nitrobenzene added in portions of 5—10 c.c. at a time. Heat is evolved, and the mass becomes somewhat deeper in colour. When the nitrobenzene has been added, the flask is heated for a shoit time on the water-bath. K few drops are then potiied into a test-tube of water. The dinitrobenzene should, if the reaction is complete, separate out as a hard pale yellow cake If it is semi-sohd, the heating" must be continued. The contents of the flask are then poured, whilst warm, into a large quantity of water. The dinitrobenzene, which separates out, is filteied at the punap and well washed with water. It is then dried. The yield is nearly theoretical. A few grams should be recrystallised from spirit. The remainder may be used for the next preparation without further puiification. 

Procedure. To a 50 mL sample of the water to be tested add 1 mL buffer solution (ammonium hydroxide/ammonium chloride, pH 10, Section 10.54) and 30-40 mg solochrome black indicator mixture. Titrate with standard EDTA solution (0.01 M) until the colour changes from red to pure blue. Should there be no magnesium present in the sample of water it is necessary to add 0.1 mL magnesium-EDTA solution (0.1 M) before adding the indicator (see Section 10.54). The total hardness is expressed in parts of CaC03 per million of water. 

Formulations (clear liquids or coloured formulations) based on an ethanol solution of various silica or aluminosilica precursors are marketed for application on glass, metallic or plastic surfaces to achieve hard 1 10 pm coatings that form strong chemical bonding with the surfaces and protect against staining or water corrosion. 

The purification of ammonium chloride.—Crude sal ammoniac is usually contaminated with iron or tarry matters, and in consequence, the colour varies from yellow to red it can be purified by heating it in thin layers on an iron plate hot enough to drive off the water and free acid, and to carbonize most of the tarry products. The grey mass is then sublimed. The sublimation is conducted in cast-iron pots lined internally with firebricks, and covered with a lid made of slightly concave plates. The salt to be sublimed is well dried, and heated. The pots hold about half a ton, and the sublimation occupies about five days. The sublimate forms a solid fibrous crust about 4 inches thick. The crust is easily detached from the lid it is then broken up, separated from adhering dirt, and packed for the market in barrels or sacks. W. Hempel 9 proposed converting the crystalline salt into hard stone-like masses by press, between 50° and 100°. 

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