Showing 552 items
matching use of machinery
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Churchill Island Heritage Farm
Machine - Wool Press
These presses were used in shearing sheds around the country to create bales of wool by hand in preparation for transport to the wool markets for purchase and distribution. Bales have been used to store and were a standard trading unit for wool for centuries. A standard wool bale holds about 60 compressed wool fleeces and weighs a minimum of 120 kgs. The square shape and weight enabled them to be stacked on wagons or in warehouses, and a large pack horse could carry one on each side. With technological advances, the bales are now formed in electrical and hydraulic presses.All metal wool press, unpainted, surface rustfarm machinery, wool, wool press, hand operated, shearing -
Churchill Island Heritage Farm
Functional object - Bag lifter, 1925
Metal crook with two gently curved arms, and used for lifting bagschurchill island, farm machinery, lifter -
Churchill Island Heritage Farm
Functional object - Garden barrow
Found in Amess Barn 1980s, this garden barrow is a typical example found on farms. Constructed using found materials and excess pieces, the garden barrow is analogous to the modern wheelbarrow.Handmade garden wheelbarrow with wooden flat tray made from abutting planks and single metal wheelfarm machinery, barrow, hand operated, hand made -
Churchill Island Heritage Farm
Functional object - Horseworks, 1880
Horseworks for one or two horses, gearing, shafting and pulley, complete. Used as a power conversion unit via one or two horses to operate a chaff cutter or similar unit. Horseworks is set up outside a building with an underground shaft to a pulley inside the barnRobinsonfarm, machinery, horseworks, power, horse, churchill island -
Churchill Island Heritage Farm
Functional object - Babcock Milk Tester
This milk tester was developed by Stephen Babcock in 1890 to discourage milk adulteration. Some farmers would dilute the milk with water or skim off some of the cream. To undertake the test, milk was put into a special flask with a long neck, called a Babcock bottle, an amount of sulfuric acid was added to the milk. This would dissolve proteins and others components and leave the fat. The bottles were then placed on the tester. Heating and centrifuging would cause the fat to separate and float to the top in a layer free of bubbles. The centrifuging was done by speedily turning the handle (the handle is missing on this tester). The amount of fat could then be estimated from the volume of that layer. This Babcock Milk Tester was of the type used by previous owner of Churchill Island, Harry Jenkins, who owned a dairy farm.Slate steel hand operated centrifuge, with a long wooden crank attaching to the body. Eight uncoloured metal protrusions for attaching to the bottles/pipettes connect with the crank, and the feet of the machine have two holes for secure attachment to a surface. This object has been riveted to a wooden board. Babcock Tester, Officialfarm, machinery, dairy, equipment, babcock tester, hand operated, fat content, babcock, churchill island -
Churchill Island Heritage Farm
Functional object - Milk/Cream Separator
This device would separate the cream from milk using a hand operated lever. When turned, the lever would activate a disc which would spin the separator bowl at a great speed. Through this use of centrifugal force, the cream would gather in the middle while the milk would be pulled towards the outside walls of the bowl. Once the rotation ceased, the milk and cream would flow out of two separate spouts. Prior to the invention of the separator, gravity was used to naturally separate the cream from the milk. The cream rose to the top and was then skimmed by hand. This process was lengthy and often resulted in sour milk, so the invention of the mechanical separator was popular in the dairy industry as there was less waste and encouraged greater production levels. Alfa Laval is a Swedish company founded in 1883. Beginning with domestic farm machinery and dairy products, they expanded to heavy industry and are still successful today. Metal cream separator mounted on red base with bowl, double spouts.Alfa Lavalfarm machinery, dairy equipment, milk, cream, separator, hand operated -
Churchill Island Heritage Farm
Functional object - Milk/cream separator
This device would separate the cream from milk using a hand operated lever. When turned, the lever would activate a disc which would spin the separator bowl at a great speed. Through this use of centrifugal force, the cream would gather in the middle while the milk would be pulled towards the outside walls of the bowl. Once the rotation ceased, the milk and cream would flow out of two separate spouts. Prior to the invention of the separator, gravity was used to naturally separate the cream from the milk. The cream rose to the top and was then skimmed by hand. This process was lengthy and often resulted in sour milk, so the invention of the mechanical separator was popular in the dairy industry as there was less waste and encouraged greater production levels. Silver bowl with black base with handle; mounted on boardfarm, machinery, dairy, equipment, milk, cream, separator, hand operated, churchill island -
Churchill Island Heritage Farm
Functional object - Milk/cream separator
This device would separate the cream from milk using a hand operated lever. When turned, the lever would activate a disc which would spin the separator bowl at a great speed. Through this use of centrifugal force, the cream would gather in the middle while the milk would be pulled towards the outside walls of the bowl. Once the rotation ceased, the milk and cream would flow out of two separate spouts. Prior to the invention of the separator, gravity was used to naturally separate the cream from the milk. The cream rose to the top and was then skimmed by hand. This process was lengthy and often resulted in sour milk, so the invention of the mechanical separator was popular in the dairy industry as there was less waste and encouraged greater production levels. This separator is missing its bowl, however the two spouts for the milk and the cream can clearly be seen.Metal top, bowl missing ;burgundy pedestal base with handlefarm machinery, dairy equipment, milk, cream, separator, hand operated -
Churchill Island Heritage Farm
Functional object - Butter worker, 30lb capacity, 1930s
... Churchill Island VIC phillip-island-and-the-bass-coast Used ...Used at Chrchill Island, Timber with cast gearing, round butter workerCherry & Sonsfarm machinery, dairy, butter, butter worker, hand operated -
Churchill Island Heritage Farm
Functional object - Milk separator, 1930s
The milk separator used centrifugal force to separate the cream and milk. A wooden crank handle would have been attached to the side of the machine (where the handle attached can be seen on the right-hand side). The milk was poured into the bowl on the top and the handle had to then be turned fast enough to get the separator up to speed adequate to separate the cream and the milk. The milk would come out of one spigot and the cream out of the other. Silver bowl with red base; some suface rustchurchill island, farm machinery, dairy equipment, milk, cream, separator, hand operated -
Churchill Island Heritage Farm
Functional object - Butter Churn, 1935
Butter Churns were commonly used on farms to turn cream into butter. The cream was placed inside the container and the lid was placed on top to prevent spillage. Turning the handle on the side of the box would move a paddle inside to agitate the cream and turn it into butter. This process would require approximately 20-30 minutes of consistent work to produce results. The Cherry & Sons model butter churn was used in the early parts of the 20th century and could make up to 6kgs of butter.Unpainted wooden box, with brass handle and wooden lidfarm, machinery, dairy, equipment, butter, churn, hand operated, churning, churchill island -
Churchill Island Heritage Farm
Functional object - Cheese Press, 1880
The cheese press was a manual device used for the final steps in making cheese. Widely used throughout the nineteenth and early twentieth centuries, there were many different styles including the screw lever press, spring presses, and this horizontal design. Two presses were generally done: the first gave form to the ‘cheese’, ensuring it was appropriately dense, and the second used a greater weight to eliminate the excess whey. Each pressing took place overnight, and after complete, the cheese was wrapped in a muslin cloth, date stamped and stored in a cool room. The manufacturer of this cheese press was J & T Young Ltd, and was probably manufactured at the Vulcan Foundry in Ayrshire, Scotland. Metal cheese press, whitefarm machinery, dairy, churchill island, cheese, hand operated -
Churchill Island Heritage Farm
Tool - Grindstone, 1920s
Rotary grindstones have been in consistent use for centuries as devices to sharpen or shape ferrous metals. Pedal-operated rotary grindstone on timber stand. The circular stone is attached to a four legged stand, with a length of wood linking to a pedal. Unpainted, unfinished, and slight deterioration. farm machinery, grindstone, churchill island, rotary, farm -
Churchill Island Heritage Farm
Functional object - Stationary engine, red, 1925
“Sundial 2hp engine, open crank, 600rpm, serial number 6420.” These small 4 stroke engines were widely used on Australian farms through the 20th century to power chaffcutters, grinders, saws, lighting plants, pumps, shearing plants, milking machines and cream separators easing much of the drudgery of farm work. They were also used in garages and workshops and by bush fire brigades. The engine was made by H.V.McKay Massey Harris. At one time Hugh Victor McKay’s Sunshine Harvester Works was the largest factory in Australia but in 1930, to ensure survival during the Great Depression, elected to merge with the Australian arm of a Canadian firm, Massey Harris. The Sundial is fitted with twin flywheels, making it a compact and convenient power source as either wheel could double as a drive wheel. Its connecting rod, crankshaft and flywheel spokes are covered, a safety measure that was not standard at the time. These engines were advertised as simple, dependable, low in price and cheap to run. They had the additional advantage that a bolt-on kit was made by the manufacturer to convert them to run on kerosene. ‘The engine's output is two horsepower (1.5 kW) at 600 rpm. The compression ratio is 5:1 and the spark plug is activated by a high tension magneto. The fuel tank holds 3.3 litres and the cooling water hopper holds 6.6 litres. Cylinder bore is 101 mm and piston stroke is 115 mm.’ In a catalogue of HV McKay Massey Harris agricultural machinery published in March 1942, the engine is described as follows: 'The cylinder head is of the hot, turbulent type, giving the finest fuel atomisation and heat distribution. The carburettor, of special design, has an automatic air valve controlling the amount of air. The supersensitive, high speed, flyball-type governor provides an ample range of speed.'Typical of units used on local farms. RepresentativeSundial 2 h.p. engine, open crank 600 rpm Seral number 6420, red. Attached to yellow grain grinderSunshine McKay, 1939 Serial no. 6420farm machinery, stationary, machine operated, belt driven -
Churchill Island Heritage Farm
Functional object - Engine
The Moffat Virtue Company was founded by John Moffat (1841 – 1918) and William Virtue (1863 – 1926) in Sydney. Both men were born in Scotland, John Moffat was a mining entrepreneur who migrated to Queensland in 1861 and began mining in the far north of Queensland. William Virtue was a talented mechanical engineer who became acquainted with John Moffat through their mutual involvement with the New Jerusalem Church and the teachings of theologian Emanuel Swedenborg. Moffat invited Virtue to migrate to Queensland, which he did with his young family but they finally settled in Sydney. Moffat had become interested in shearing machines and Virtue’s engineering skills enabled the registration of several patents in 1891 – 1894. The Moffat Virtue alliance grew and prospered and by 1911 all the entrants in the first sheep shearing competition at the Sydney Royal Show chose the company’s machines. By 1914 Moffat Virtue was a household name in rural Australia due to manufacture of agricultural machinery and household appliances. The company began making petrol engines in 1920 at 205 Clarence Street, moved to 11 – 25 Palmer Street in 1929 and later moved to Rosebery. The petrol-kerosene engine was popular as the use of kerosene made it very cheap to run. The motor starts by using petrol and once the engine is warmed, the vaporiser is activated which enables the use of kerosene as the running fuel. The carburettor and cylinder head are designed to ensure thorough vaporisation and complete combustion of fuel, resulting in maximum horsepower at lowest fuel consumption The serial number indicates 1944 as the approximate date of manufacture.Green petrol engine with red trim and crank handle. Attached to green grain grinder“Moffat Virtue Petrol Kerosene Engine No. 9142 1000RPM 3HP Change oil every 90 working hours SAE 40 For severe service and in Summer SAE 30 Warranty void unless above instructions followed” farm, machinery, stationary engine, crank, belt driven, engine, churchill island -
Churchill Island Heritage Farm
Functional object - Furphy Water Cart, 1929
The family-owned Furphy company has been manufacturing agricultural equipment in Kyneton and then Shepparton in Victoria from the 1860s to the present day. In the late 1800s the company developed the Furphy Water Cart to help farmers transport water to and from and around their properties - especially in time of drought. At the beginning of World War One, the carts were used to distribute water amongst the thousands of soldiers completing their basic training at Broadmeadows. They were also used for the same purpose in the camps and battlefields overseas. As the soldiers gathered around the water carts they would often chat, share information and gossip amongst themselves. These practices resulted in the term Furphy evolving in to the Australian vernacular as meaning a statement or fact that isn’t quite true or a little bit dubious.Furphy water cart, unpainted with traces of red on embossed endOn side of tank in black paint "CHURCHILL ISLAND" Embossed on end: Furphy water cart; makers Furphy & Sons, Shepparton and other inscriptions.farm machinery, water, furphy cart, horse drawn, furphy, churchill island, shepparton, kyneton -
Churchill Island Heritage Farm
Functional object - Stationary engine
This engine has a blue green casing and has been made portable as it is mounted on a tray supported by four red metal wheels. It could be moved around the paddocks or sheds pulled by horses or oxen. There is no identification plate on the engine and there are no maker’s stamps or marks therefore it is difficult to name the company responsible for its manufacture. Engines like this were invaluable on farms to operate threshing and milling machines, pumps, saw benches, hay balers and chaffcutters, among other things. This engine is currently attached to a chaff cutter. The value is also in the fact that it has two belt drive wheels so could be used to perform two different operations simultaneously depending on available horsepower.Blue green casing; two belt drive wheels; red wheels. Attached to green chaff cutterchurchill island, farm machinery, stationary engine, belt driven -
Churchill Island Heritage Farm
Tool - Double ended spanner
The double-ended ring spanner served as a useful, manual tool for maintaining farm machinery. The hexagonal rings would be placed over a nut to secure it, before the spanner was rotated to tighten the nut. The ring design provides greater purchase, or grip on all sides of the nut, which in turn reduces the risk of rounding the nut, or slippage. Early spanners were mostly made from iron and hand-forged using an anvil and hammer. Since the mid-19th century, gravity or powered drop forging techniques were used to compress metal for greater strength. Ring spanners produced in the 20th century are mostly made of chrome vanadium steel.stainless steel, some pitting. One end slightly smaller than the otherdouble, ended, spanner, tool, tools, churchill island, farm -
Churchill Island Heritage Farm
Tool - Crosscut Saw
Cross cut saws have been used for millennia, but they came into wider usage in Europe from the 15th century onwards. The term 'cross cut' refers to the blades on the saw’s cutting edge which come in a variety of different patterns. These saws are specifically designed for cutting across the grain of the wood by timber workers, sawyers, and other land workers for tree felling and cutting up larger pieces of lumber into smaller more manageable pieces. The saws come in variable sizes and lengths and are designed for use by one or two people. With the two-man saws, a method of alternating 'pull and push' to drag the blade back and forth through the timber, maximising efficiency and labour division.one end original minus handle. Other end has replaced handle. Steelchurchill island, crosscut, saw, tool, machinery -
Churchill Island Heritage Farm
Tool - Crosscut Saw
Cross cut saws have been used for millennia, but they came into wider usage in Europe from the 15th century onwards. The term 'cross cut' refers to the blades on the saw’s cutting edge which come in a variety of different patterns. These saws are specifically designed for cutting across the grain of the wood by timber workers, sawyers, and other land workers for tree felling and cutting up larger pieces of lumber into smaller more manageable pieces. The saws come in variable sizes and lengths and are designed for use by one or two people. With the two-man saws, a method of alternating 'pull and push' to drag the blade back and forth through the timber, increasing efficiency.double ended steel saw with "M" patterned teeth. Handles missing. All rivets in placechurchill island, crosscut, saw, tools, machinery -
Churchill Island Heritage Farm
Tool - Crosscut Saw
Cross cut saws have been used for millennia, but they came into wider usage in Europe from the 15th century onwards. The term 'cross cut' refers to the blades on the saw’s cutting edge which come in a variety of different patterns. These saws are specifically designed for cutting across the grain of the wood by timber workers, sawyers, and other land workers for tree felling and cutting up larger pieces of lumber into smaller more manageable pieces. The saws come in variable sizes and lengths and are designed for use by one or two people. With the two-man saws, a method of alternating 'pull and push' to drag the blade back and forth through the timber, maximising efficiency and labour division.single handed cross-cut saw. Peg grip missing?circular brass manufacturer's plate: SPEAR & JACKSON Sheffield. Crown symbol.churchill island, crosscut, saw, tool, machinery -
Churchill Island Heritage Farm
Tool - Crosscut Saw
Cross cut saws have been used for millennia, but they came into wider usage in Europe from the 15th century onwards. The term 'cross cut' refers to the blades on the saw’s cutting edge which come in a variety of different patterns. These saws are specifically designed for cutting across the grain of the wood by timber workers, sawyers, and other land workers for tree felling and cutting up larger pieces of lumber into smaller more manageable pieces. The saws come in variable sizes and lengths and are designed for use by one or two people. With the two-man saws, a method of alternating 'pull and push' to drag the blade back and forth through the timber, maximising efficiency and labour division. Donated by Wilfred Dungan on behalf of the Dungan family Collection originally used on the property of the late Dr Rae Dungan in Falls Creek Rd Olinda, purchased in the late 1930s from Olinda pioneers Harry and Minnie Holden. Also on the property of late May Farndon of Farndon’s and Falls Rd Mt Dandenong – aunt of Dr Rae William Dungan and also an early pioneer. Family holidays and weekends involved use of these sorts of farm implements plus working with horses. Post-war, the Olinda hand tools and machinery moved to the Shady Creek, Nilma North area where bush, pasture and cows had replaced the Olinda property. Wilfred well remembers being on one end of the crosscut saws cutting fence posts, logs and timber under “the tireless and vocal instruction” of a red headed local Darnum Rd legend called Harry Collyer. “He drove an old Rugby car and nearly pulled me through the logs with every cut!” steel blade, wooden handle and peg grip. Single person sawcrosscut, saw, churchill island, tool -
Churchill Island Heritage Farm
Tool - Crosscut Saw
Cross cut saws have been used for millennia, but they came into wider usage in Europe from the 15th century onwards. The term 'cross cut' refers to the blades on the saw’s cutting edge which come in a variety of different patterns. These saws are specifically designed for cutting across the grain of the wood by timber workers, sawyers, and other land workers for tree felling and cutting up larger pieces of lumber into smaller more manageable pieces. The saws come in variable sizes and lengths and are designed for use by one or two people. With the two-man saws, a method of alternating 'pull and push' to drag the blade back and forth through the timber, maximising efficiency and labour division. Donated by Wilfred Dungan on behalf of the Dungan family Collection originally used on the property of the late Dr Rae Dungan in Falls Creek Rd Olinda, purchased in the late 1930s from Olinda pioneers Harry and Minnie Holden. Also on the property of late May Farndon of Farndon’s and Falls Rd Mt Dandenong – aunt of Dr Rae William Dungan and also an early pioneer. Family holidays and weekends involved use of these sorts of farm implements plus working with horses. Post-war, the Olinda hand tools and machinery moved to the Shady Creek, Nilma North area where bush, pasture and cows had replaced the Olinda property. Wilfred well remembers being on one end of the crosscut saws cutting fence posts, logs and timber under “the tireless and vocal instruction” of a red headed local Darnum Rd legend called Harry Collyer. “He drove an old Rugby car and nearly pulled me through the logs with every cut!” Two handled cross cut saw. One manufactured handle and one bush replacement wedged with three inch nail. 6 broken teeth. Rivets for handle broken off at home-made end. M shaped tooth profile.churchill island, crosscut, saw, tool -
Churchill Island Heritage Farm
Tool - Scythe
... and is used by making large sweeping motions through the crop...-drawn or motorised machinery, they are occasionally still used ...A scythe is an agricultural hand tool that cuts grass and is used by making large sweeping motions through the crop. Eventually replaced by horse-drawn or motorised machinery, they are occasionally still used as they are inexpensive and efficient. There are different types of scythes with larger or smaller blades. This particular scythe was manufactured by W.A Tyzack & Co. Ltd. Set up by William Tyzack in the early 1800s in Sheffield, United Kingdom, they grew into a larger manufactory specialising in agricultural tools. Adding the ‘Horseman’ brand to their trademark in 1948, they expanded dramatically and exported throughout the Commonwealth.Donated by Wilfred Dungan on behalf of the Dungan family Collection originally used on the property of the late Dr Rae Dungan in Falls Creek Rd Olinda, purchased in the late 1930s from Olinda pioneers Harry and Minnie Holden. Also on the property of late May Farndon of Farndon’s and Falls Rd Mt Dandenong – aunt of Dr Rae William Dungan and also an early pioneer. Family holidays and weekends involved use of these sorts of farm implements plus working with horses. Post-war, the Olinda hand tools and machinery moved to the Shady Creek, Nilma North area where bush, pasture and cows had replaced the Olinda property. Wilfred well remembers being on one end of the crosscut saws cutting fence posts, logs and timber under “the tireless and vocal instruction” of a red headed local Darnum Rd legend called Harry Collyer. “He drove an old Rugby car and nearly pulled me through the logs with every cut!” Cast steel blade. Hole on back and of blade for hanging. Steamed handle (may not be original). Complex pipe/nut washer and five metal shims keeping blade on handle.From tip: BEST CROWN W.A. TYZACK & CO. LTD STELLA WORKS SHEFFIELD. Near handle: image of figure on horse.churchill island, scythe, wa tyzack, sheffield, machinery -
Churchill Island Heritage Farm
Fern hook
Donated by Wilfred Dungan on behalf of the Dungan family Collection originally used on the property of the late Dr Rae Dungan in Falls Creek Rd Olinda, purchased in the late 1930s from Olinda pioneers Harry and Minnie Holden. Also on the property of late May Farndon of Farndon’s and Falls Rd Mt Dandenong – aunt of Dr Rae William Dungan and also an early pioneer. Family holidays and weekends involved use of these sorts of farm implements plus working with horses. Post-war, the Olinda hand tools and machinery moved to the Shady Creek, Nilma North area where bush, pasture and cows had replaced the Olinda property. Wilfred well remembers being on one end of the crosscut saws cutting fence posts, logs and timber under “the tireless and vocal instruction” of a red headed local Darnum Rd legend called Harry Collyer. “He drove an old Rugby car and nearly pulled me through the logs with every cut!” Curved blade, painted black. Wooden limb handle, varnished, some white paint spots. Nail into handle in blade holder sleeve. Slight bulge in handle near blade holderchurchill island, fern hook, olinda, mount dandenong, nilma north -
Churchill Island Heritage Farm
Tool - spanner
Thin metal spanner, with a curved head and a hook at the end. Badly rusted. Intended for commercial use and as an accompaniment with machinery.churchill island, spanner, tool -
Churchill Island Heritage Farm
Tool - Scythe
... and is used by making large sweeping motions through the crop...-drawn or motorised machinery, they are occasionally still used ...A scythe is an agricultural hand tool that cuts grass and is used by making large sweeping motions through the crop. Eventually replaced by horse-drawn or motorised machinery, they are occasionally still used as they are inexpensive and efficient. There are different types of scythes with larger or smaller blades. This particular scythe has a bored hole in the handle, probably for affixing a long wooden handle. Made by Trojans and Sons, a Melbourne based company that made a wide range of gardening and agricultural tools, this scythe formed an integral part of farming on Churchill Island. scythe with surface rust, no handle, good steel, rough welds on socket, hole for mounting handle (e.g. with screw)TROJAN/264scythe, hand tools, agriculture, churchill island heritage farm -
Churchill Island Heritage Farm
Functional object - Pump, c. 1930
Farm pumps were used to drain or raise water in a variety of situations. The belt mechanism of this pump was a flat band encircling two pulleys which drove the pump. Belt driven pumps were easy to maintain. They did not need lubrication or collect grime and they did not rust. Their operation was relatively quiet with less vibration, again reducing maintenance. The engine would be powered by kerosene or petrol.Green pump with a white exhaust pipe angled vertically. Mounted on an untreated wooden stand.farm machinery, pump, belt driven -
Bendigo Historical Society Inc.
Photograph - BILL ASHMAN COLLECTION: PHOTOGRAPH OF CARBON REMOVED FROM MACHINERY AFTER SCALEBUOY USED
... from machinery after scalebuoys have been used, description... deposits removed from machinery after scalebuoys have been used ...Black and white photograph showing carbon deposits removed from machinery after scalebuoys have been used, description printed on back.Vincent Kellyphotograph -
Bendigo Historical Society Inc.
Leisure object - WOODEN MODEL CYANIDE PLANT
... . The ore is comminuted using grinding machinery. Depending ...Wooden model of a cyanide plant. A cyanide plant was used for dissolving gold from finely divided ores by means of dilute solutions of sodium or potassium cyanides. The model has five metal bins, there is some rust on the bins and scorch mark on the wooden base.mining, equipment, cyanide plant, gold cyanidation (also known as the cyanide process or the macarthur-forrest process) is a hydrometallurgical technique for extracting gold from low-grade ore by converting the gold to a water-soluble coordination complex. it is the most commonly used leaching process for gold extraction. the ore is comminuted using grinding machinery. depending on the ore, it is sometimes further concentrated by froth flotation or by centrifugal (gravity) concentration. water is added to produce a slurry or pulp. the basic ore slurry can be combined with a solution of sodium cyanide or potassium cyanide, however many operations utilize calcium cyanide, which is more cost effective. to prevent the creation of toxic hydrogen cyanide during processing, slaked lime (calcium hydroxide) or soda (sodium hydroxide) is added to the extracting solution to ensure that the acidity during cyanidation is maintained over ph 10.5 - strongly basic. lead nitrate can improve gold leaching speed and quantity recovered, particularly in processing partially oxidized ores.