Knife files

Wallerius in 1747 used a finger nail, knife, file or diamond powder for hardness determination. Werner in 1774 rubbed a mineral against a finger nail, knife or piece of steel to determine the quantities of powder thus derived. Hatty (1801) used calcite and quartz as well as glass for this purpose. The first arbitrarily chosen scale of hardness, containing exclusively minerals, was devised in Sweden by Kvist in 1768. It covered diamond—20, topaz—15, zeolite—13, quartz—11, fluorite—7, calcite—6, gypsum—5 and chalk—2. 

But convenient as it is in the rOle of air bath for simple drying operations, it will be found more so where drying tubes or retorts have to be manipulated at constant temperature. The flower pot can be perforated at any place, and holes of any size or shape can be drilled and cut through it with an old knife, file, or other implement. Thus in C it is shown in use... 

A sample should be prepared properly and then placed in a container before it is irradiated. The person who prepares the sample should be extremely careful not to contaminate it. Activation analysis is so sensitive that it can determine traces of elements undetectable by chemical methods. If the sample is left on a table for a certain period of time, it collects dust that acts as a contaminant. Touch by hand may transfer enough salt to cause the irradiated sample to show the presence of sodium and chlorine. To avoid contamination, samples should be handled in dry boxes or in clean rooms. The person who prepares the sample should use clean instruments (knife, file, tweezers, etc.) and also wear clean plastic gloves. 

Fused silica is slightly more brittle than borosilicate glasses and is therefore more easily fractured. Tubes up to just over 1 cm in diameter can be snapped with the fingers after scratching with a file or glass knife. Any ragged end so formed can be cleaned up with an abrasive wheel. 

Onhoclase) or Perietase 6.5 Sled i Knife Blade File)... 

Caustic Soda.—-This is supplied in powder, stick, flake and pellet forms, the last two being convenient to use. The pure variety comes on the market in the form of sticks. In weighing out a quantity, the sticks should not be handled. Pieces of a desired size can be broken off by elevating one end and dealing a sharp blow with a knife or file at the desired point. The same remark applies to caustic potash sticks. 30—40% solutions of caustic soda are available in commerce. Usual impurities chloride, carbonate, and chlorate of sodium. 

Plaster of Paris heavy-duty aluminum foil X-ACTO knife plaster files ... 

Paper pencil small (3-x-4-in.) cardboard box with lid plaster of Paris or casting plaster water iron skimmer ladle pewter in sheet or ingot form wire (stove pipe) pliers carving tools (simple knife nail file pencil old dental tools or anything that will carve plaster) wire cutters propane torch fireproof surface (casting container of sand) steel wool jeweler s saw and blades files X-ACTO knife C-clamp leaves. 

We know that diamond can scratch glass, but so can hard metals such as the hardened steel of a file or a tungsten-carbide glass knife. A beaker that is slid or... 

In reference to the article on "How to Convert a File Into a Hunting Knife" on page 61 of Vol. I. 

A large pen can be used to hide a knife. I took a large size felt point pen, gutted it, then made a blade from a three cornered file. Then I set the blade in the cap. You can have a three inch blade with you at all times. Use to set the blade if the... 

FIG. 4.5. h on wire hooks. Tlie glass tube is scratched witli a knife or file, tlie wire hook is heated to cheiiy red. Hie tube is held horizontally and rotated witli the scratch in contact witli the hot wiie. A crack will immediately appear and travel round the tube, leaving a clean straight cut end. 

A sawing action with either knife or file is unnecessary, and will only blunt the tool one single straight mark made with a smooth movement of the hands is all that is required. The knife or file must be sharp. If considerable pressure is required to mark the glass, the tool is blunt and must be resharpened. 

Use the 30 cm lengths of tube, the ends of which are already fused. Make a small mark at the centre of each tube with a glass-marking pencil, or, if preferred, with a glass knife or file. Now make two other similar marks on the tubes, one... 

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