Dusting powders containers

Three dusting powders containing boric acid are included in the B.P.C., ue. Boric Talc, 5 per cent of boric acid and 10 per cent of starch in talc Compound Salicylic Acid Dusting Powder, 3 per cent of salicylic acid and 5 per cent of boric acid in talc and Compound Zinc Dusting Powder, containing 5 per cent boric acid, 25 per cent zinc oxide, 35 per cent starch and 35 per cent purified talc. Boric Acid and Starch Dusting Powder, containing 25 per cent of boric acid is official in the B. Vet,C,... 

For agricultural uses, a fully hydrated calcium cyanamide powder containing 2% oil is used for dusting appHcations for general fertilizer use, the hydrated material is granulated with water in rotary dmms and dried giving a 2.38 x 0.32 mm (8 x 48 mesh) product. 

The new propellant was promising but the nitrocellulose smokeless powder invented soon afterwards superseded all mixtures containing potassium nitrate and similar salts, that give a number of solid particles when exploded. For a time in the United States various mixtures were still used instead of blackpowder—chiefly for sporting purposes. E.g. Gold Dust Powder (Starke [36]) consisted of 55% ammonium picrate, 25% potassium picrate and 20% ammonium bichromate. Soon, however, early in the nineteenth century, the use of these mixtures was discontinued. 

Another type of nitrocellulose powder used for some time which eventually disappeared from the market was a semi-colloidal nitrocellulose powder containing inorganic salts such as potassium or barium nitrate (e.g. Poudre T in France, with 2% potassium nitrate) or with dichromates (e.g. Poudre J in France with 14% ammonium dichromate and 3% potassium dichromate). The dichromate powder was very sensitive to friction and its dust contained toxic dichromates. 

The pests are destroyed by absorbing the powder either through the mouth or through the body by contact, and the sprays and dusts should contain minimum quantities of water-soluble arsenic, as this is mainly responsible for foliage injury the fineness of division also has an effect, and injury is increased if the arsenate is too highly dispersed.5 In the United States a legal limit (0-75 per cent. As2Os) is imposed as to the amount of water-soluble arsenic that may be present in lead... 

Zinc Dust.—Commercial varieties vary much in character and are subject to deterioration they contain usually 90—95% Zn (for estimation, see p. 510) they should be preserved in airtight vessels and should be occasionally estimated. Two other forms of zinc for reducing purposes are on the market—a ground zinc, made by grinding metallic zinc, and a variety in the form of powder containing 2% of lead, which gives specially good results. Usual impurities zinc oxide, iron and arsenic. 

Although this natural substance is present in a number of plants, the sonrce of most rotenone nsed in the United States is the dried derris root imported from Central and South America. It is formulated as dusts, powders, and sprays (less than 5% active ingredient) for use in gardens and on food crops. Many prodncts contain piperonyl butoxide as synergist, and other pesticides are inclnded in some commercial products. Rotenone degrades rapidly in the enviromnent. Emulsions of rotenone are applied to lakes and ponds to kill fish. 

Air elutriators are especially useful for powders that are, in praetice, subject to grading by airflow e.g. fine dust, which contains particles of different densities with settling velocities, which are not uniquely related to physical dimensions. The major problems encountered in air elutriation are the difficulty in break up agglomerates and preventing particles from sticking to the walls of the elutriator tubes. The three main types of air elutriator are the up-blast, the down-blast and the circulating. 

The zinc vapor is condensed in fire-clay receivers. At first the zinc is condensed in the cool condenser as a fine powder, called zinc dust, which contains some zinc oxide. After the receiver becomes hot the vapor condenses to a liquid, which is cast in ingots called spelter. Spelter contains small amounts of Cadmium, iron, lead, and arsenic. It can be purified by careful redistillation. 

In topical preparations, talc is used as a dusting powder, although it should not be used to dust surgical gloves see Section 14. Talc is a natural material it may therefore frequently contain microorganisms and should be sterilized when used as a dusting powder see Section 11. 

Inert ingredients in liquid pesticides include water, alcohol, and other solvents. Pesticide powders and dusts often contain added diatomaceous earth, powdered seeds, or talc for added bulk, or fuller s earth to help prevent caking. Other inert ingredients, known as surfactants, help powders mix easily with water or help sprays adhere to foliage so that pests are more likely to contact it. In the absence of surfactants, many pesticide sprays would simply roll off waxy leaf surfaces. Soap is one of the most common surfactants added to pesticide sprays. 

The subcoat is an adhesive coat on which the smoothing coat can be built. A second purpose of the subcoat is to round off the sharp corners of the tablet to produce a smooth surface. The subcoat is a mixture of a sucrose solution and an adhesive gum, such as acacia or gelatin, which rapidly distributes over the tablet surface. A dusting follows each application of solution with a subcoat powder containing materials such as calcium carbonate, calcium sulphate, acacia, talc and kaolin that help to produce a hard coat. The application of the subcoat continues until the tablets have a rounded appearance and the edges are well covered. 

Systems with a gaseous dispersion medium, known under the common name of aerosols, include smokes, dusts, powders (systems of S/G type) and fogs (L/G type systems). Aerosols containing both solid particles and liquid droplets of dispersed phase are referred to as smogs. Since gases are totally miscible with each other, the formation of disperse systems of G,/G2 type is impossible. Nevertheless, even in the mixtures of different gases one can encounter non-uniformities caused by the fluctuations in density and concentration. 

False Powder-Post Beetles. False powder-post beetles (Bostrychidae) fill their chambers with a coarse boring dust that contains small wood fragments. They will attack both hardwood and softwood. 

In domestic life, crannies are sprayed with organophosphates to banish silverfish, termites, and cockroaches. Domestic pets are dusted with powders containing propoxur 13.40) or carbaryl 13.39), these carbamates, because of their short half-life in the human, are esteemed because medicated pets will be embraced by children. 

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