Dullness

SiToniium peroxide, Sr02, is formed from SrO and O2 at dull red heat under pressure. Sr02,8H20 is formed from Sr(OH)2 plus H2O2 in cold aqueous solution. 

If a carbohydrate is present, a red ring appears at the common surface of the Uquids the colour quickly changes on standing or shaking, a dark purple solution being formed. Shake and allow the mixture to stand for 2 minutes, then dilute with 5 ml. of water. In the presence of a carbohydrate, a dull-violet precipitate will appear immediately. 

An additional useful test is to distil the acid or its sodium salt with soda lime. Heat 0.5 g. of the acid or its sodium salt with 0 2 g. of soda lime in an ignition tube to make certain that there is no explosion. Then grind together 0-5 g. of the acid with 3 g. of soda hme, place the mixture in a Pyrex test-tube and cover it with an equal bulk of soda hme. Fit a wide dehvery tube dipping into an empty test-tube. Clamp the tube near the mouth. Heat the soda lime first and then the mixture gradually to a dull-red heat. Examine the product this may consist of aromatic hydrocarbons or derivatives, e.g., phenol from sahcyUc acid, anisole from anisic acid, toluene from toluic acid, etc. 

Place about 01 g. of the compound in a porcelain crucible or crucible cover. Heat it gently at first and finally to dull redness. Observe ... 

Copper oxide powder, prepared by grinding copper oxide (wire form), is heated to dull redness in a porcelain basin, allowed to cool partially in the air and finally in a desiccator. 

Arsenic. The presence of arsenie in an organie eompound is generally revealed by the formation of a dull grey mirror of arsenic on the walls of the test-tube when the eompound is fused with sodium in the Lassaigne teat. Usually sufficient arsenic is found in the fusion solution to give a yellow precipitate of arsenic trisulphide when the solution is acidified with hydrochloric acid and treated with hydrogen sulphide. 

D. Now the ether will be a deep reddish yellow. Distill off the ether...quack...and take the temp up to 170 C to drive off any other volatiles. Should recover 90%+ of the original weight of oil. Now add 500 ml of saturated bisulfite and stir for 1.5 hours...Quack Vacuum Filter, the duck fat crystals Wash with water and ether, yield dull fine ppt in the filter cake...stable bisulfite addition product...can be stored forever...QuackU Yield -50 to 80% depending on a ducks technique ... 

When ignited, nonfilled acetal resins bum in air with a characteristic dull blue flame. 

With sheet or pipe, multilayer coextmsion can be used. SoHd outer-soHd core coextmsion can place an ABS grade on the outside that has special attributes such as color, dullness, chemical resistance, static dissipation, or fire-retardancy over a core ABS that is less expensive or even regtind. 

The original yams were marketed as silk substitutes for use in apparel, hosiery, lace, home furnishings, ribbons, braids, and in a whole range of fabrics using blends with cotton or wool yams. As the end uses expanded beyond silk replacement, the harsh metallic luster of the yam proved disadvantageous and dull "matt" fibers had to be developed. Oil dulling was invented (11) in 1926, and an improved method using titanium dioxide was developed (12) in 1929. 

Reverberation Control. Reverberation time (T q) is defined as the length of time in seconds for the sound of an instantaneously stopped source in a room to decay by 60 decibels (dB). Reverberation time is one important factor in determining the acoustical character of a space and its suitabiHty for specific activities. For lectures and other speech activities a relatively short reverberation time is desirable so that syllables do not persist and overlap one another, causing difficulty with inteUigibiHty conversely, for music activities, a relatively long reverberation time is desirable to allow blending of the sound and a sense of being surrounded by the music. Without reverberation music usually sounds dull and lifeless. 

A high concentration of the fluorescent dye itself in a solvent or matrix causes concentration quenching. Rhodamine dyes exhibit appreciable concentration quenching above 1.0%. Yellow dyes, on the other hand, can be carried to 5 or even 10% in a suitable matrix before an excessive dulling effect, characteristic of this type of quenching, occurs. Dimerization of some dyes, particularly those with ionic charges on the molecules, can produce nonfluorescent species. 

Pyrolusite is a black, opaque mineral with a metallic luster and is frequendy soft enough to soil the fingers. Most varieties contain several percent water. Pyrolusite is usually a secondary mineral formed by the oxidation of other manganese minerals. Romanechite, a newer name for what was once known as psilomelane [12322-95-1] (now a group name) (7), is an oxide of variable composition, usually containing several percent water. It is a hard, black amorphous material with a dull luster and commonly found ia the massive form. When free of other oxide minerals, romanechite can be identified readily by its superior hardness and lack of crystallinity. 

Pigment-coated printing papers usually are required to have high brightness to achieve contrast between the printed and unprinted areas. The coatings frequendy have a glossy surface. There also is a demand for duU-coated papers and for dull papers upon which glossy ink films can be printed. 

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