powder


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powder,

any mass of fine particles or dust prepared by various mechanical means, e.g., grinding of solid substances, or by chemical means, e.g., precipitation from solutions. In a special sense, the word is applied to powdered propellant explosives, e.g., gunpowder, and to powdered substances that produce a bright light when ignited. See explosiveexplosive,
substance that undergoes decomposition or combustion with great rapidity, evolving much heat and producing a large volume of gas. The reaction products fill a much greater volume than that occupied by the original material and exert an enormous pressure, which can be
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.

Powder

 

a finely ground solid, a dispersed free-flowing material.

Powder is formed by dispersion of solids and by separation of the solid dispersed phase from supersaturated solutions or vapors. The manufacture of highly dispersed powders usually involves such substances as softening solutions, dispersing agents, and stabilizers. These facilitate pulverizing and prevent the agglutination of fine particles. Particle size in powders may vary from 10-4 to 10-1 mm. Powders with particles of identical size are called monodisperse powders, and those with particles of varying size are known as polydisperse powders. Fine powders, especially hygroscopic types, are subject to lumping and caking. Highly dispersed dry powder carried off by a gas or air flow becomes dust. Powder moistened with a liquid forms a paste or dough, and when powder is rapidly agitated in a sufficiently large volume of liquid, a suspension is produced.

Many types of commercial products are manufactured and used in powder form. They include materials used in metallurgy and silicate technology; mineral binders, fillers, and pigments; ingredients for plastics, rubbers, paints, and explosives; fertilizers and pesticides; detergents; food products; and medications. Products in powder form are often granulated or compressed into tablets to ensure convenience in handling and to reduce loss and improve sanitation.

REFERENCE

Voiutskii, S. S. Kurs kolloidnoi khimii. Moscow, 1964. Page 374.

L. A. SHITS


Powder

 

a friable solid form of medicine used internally or externally. Various synthetic preparations, antibiotics, and substances of plant and animal origin are used in powder form. The following substances are not prescribed as a powder: hygroscopic substances, such as calcium chloride and sodium bromide; mixtures of substances that are fluidized upon exposure to the air, such as phenylsalicylate and bromo-camphor or antipyrine and quinine; substances that easily decompose, such as silver nitrate mixed with organic matter; or substances that form explosive mixtures. Powders may be simple (consisting of a single substance) or compound; they can be divided or not divided into individual doses.

powder

[′pau̇d·ər]
(materials)
A general term for explosives.
A loose grouping or aggregation of solid particles, usually smaller than 1000 micrometers.

powder

1. a solid substance in the form of tiny loose particles
2. any of various preparations in this form, such as gunpowder, face powder, or soap powder
3. fresh loose snow, esp when considered as skiing terrain
References in classic literature ?
We're a-changing of the powder, Jack," answers one.
As for Porthos, after having hurled the barrel of powder amidst his enemies, he had fled, as Aramis had directed him to do, and had gained the last compartment, into which air, light, and sunshine penetrated through the opening.
Next she produced several packets of herbs and powders and began adding a portion of each to the contents of the kettle.
What did old Mombi the Witch do with the Powder of Life your husband gave her?
But tell me, please, what you intend to do with this new lot of the Powder of Life, which Dr.
There wasn't a word in my story about -- about -- " Anne choked a little over the word -- "baking powder.
Well, I just stated that she used the Rollings Reliable in it, and that was why it turned out so well; and then, in the last paragraph, where PERCEVAL clasps AVERIL in his arms and says, `Sweetheart, the beautiful coming years will bring us the fulfilment of our home of dreams,' I added, `in which we will never use any baking powder except Rollings Reliable.
Next day they found a wooden Saw-Horse standing by the roadside, and sprinkled it with the Powder.
There he crushed to a powder two soluble tablets, each containing a quarter of a grain of morphia.
Another trick I tried upon him, which he innocently came into also: his name was Ismael, which they call Muley, or Moely; so I called to him - "Moely," said I, "our patron's guns are on board the boat; can you not get a little powder and shot?
The footman who opened the door, although he had powder on his head and was backed up by two other footmen likewise powdered, not only admitted Mrs Merdle to be at home, but asked Fanny to walk in.
In my extreme distress of mind, I have a morbid fear of misdirecting you; but even if I am in error, you may know the right drawer by its contents: some powders, a phial and a paper book.