Lead-shot metal

Although the element is a metalloid, the long, brittle, crystals have a metallic shine. The white, tasteless oxide (arsenic trioxide As203) has been famous and notorious ("inheritance powder") even after centuries traces can be found in bodies. The arsenic compound "Salvarsan" was first used by Paul Ehrlich for the treatment of syphilis — the start of chemotherapy. Popular today as a semiconducting material. Component of LEDs (light-emitting diodes) and lasers. Arsenic hardens lead, used earlier in letter-press printing, today only for lead shot. 

The stable form of arsenic is the gray or metallic form, although other forms are known. Cooling the vapor rapidly produces yellow arsenic, and an orthorhombic form is obtained if the vapor is condensed in the presence of mercury. Arsenic compounds are used in insecticides, herbicides, medicines, and pigments, and arsenic is used in alloys with copper and lead. A small amount of arsenic increases the surface tension of lead, which allows droplets of molten lead to assume a spherical shape, and this fact is utilized in the production of lead shot. 

The effect of diet on vulnerability to lead makes interpretation of published information on experimental lead poisoning in waterfowl extremely difficult (Chasko et al. 1984). For example, many mallards on a diet of com die within 10 to 14 days after ingesting a single lead shot, whereas similar birds on a balanced commercial duck ration appear outwardly normal after ingesting as many as 32 pellets of the same size (Wobeser 1981). Also, multiple nutritional deficiencies may have additional effects in potentiating the toxicity of lead in mallards (Carlson and Nielsen 1985). Under conditions of reduced dietary calcium availability, such as can occur in acid-impacted environments, birds risk increased uptake of lead (and other metals) and may accumulate toxic concentrations more rapidly (Scheuhammer 1996). Enhanced accumulation of lead was accompanied by an increased synthesis of metallothioneins and a greater inhibition of ALAD activity (Scheuhammer 1996). 

The major uses are in metallurgy, primarily as an additive to lead, copper, brass and many lead-base bearing alloys to improve their mechanical and thermal properties. Small amounts are added to lead in the manufacture of lead shot to improve its sphericity also added to lead-base cable sheathing and battery grid metal to improve hardness. Addition of very small quantities to copper enhances the corrosion resistance. It prevents cracking in brass. 

Group D powders They are large particles that are distinguished by their ability to produce deep spouting beds (spurt or jet of gas through the bed). Roasted coffee beans, lead shot, and some roasted metal ores are examples of group D materials. 

Arsenic. As, at wt 74.91 exists in three modifications all corresponding to the formula As4i mw 299.64. The most common form is the crystalline or a-form, known also as metallic arsenic. Its mp is 814° at 36 atm press, sublimation point 615, d 5 = 72 at RT (5.6-5.9 for commercial grade) and hardness 3.5 Mohs. Prepn props are given in Refs 1-6 toxicity, fire expln hazards of As dust are discussed in Ref 7. Arsenic is used in some alloys and for hardening lead shot... 

The applications of arsenic as a metal are quite limited. Meialluigically, it is used mainly as an additive. The addition of from to 2% of arsenic improves the sphericity of lead shot. Arsenic in small quantities improves the properties of lead-base bearing alloys for high-temperature operation. Improvements m hardness of lead-base battery grid metal and cable-sheathing alloys can be obtained by slight additions of arsenic. Very small additions (0.02 - 0.05%) of arsenic to brass reduce dezincdfication. 

Lead is a solid that melts at 327°C. Simply handling pieces of lead shot or lead foil should pose no appreciable health risk for students. Mercury. on the other hand, is a liquid of significant vapor pressure, and working with metallic mercury is known to be hazardous. The long term risk of breathing mercury vapor applies to all students, but there is a special, more immediate risk for the student who happens to be pregnant. 

Arsenic is used with lead (0.5% As) in making lead shot. It makes the metal harder than pure lead, and also improves the properties of the molten metal—the shot are made by pouring the metal through a sieve at the.top of a tall tower, which permits the liquid drops to assume a spherical form and then to harden before falling into water at the base of the tower. 

The principal ore of arsenic (5 x 10 % of earth s crust) is arsenical pyrites, FeAsS, but the element occurs commonly with nickel, copper and tin As40g is recovered from flue-dusts collected during the extraction of these metals. Sublimation in the presence of galena, which prevents the formation of arsenites, purifies the oxide this is reduced to arsenic with carbon in a cast iron retort. The element itself has few uses about 0.5% added to lead increases the surface tension of the molten metal and allows spherical lead-shot to be produced. The principal commercial form is the so-called white arsenic, As Og. Arsenic compounds are used mainly for their toxicity arsenical insecticides have been much used. 

No. 25.) In many cases the metal is allowed to run through the holes of a kind of colander or sieve to produce minute division if the drops are allowed to fall from a sufficient height, they will become spherical in this way lead shot is made. 

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