Part 4 (1/2)

A round coke and lih which an electric arc has been drawn The ot of very pure carbide surrounded by a crust of less purity The poorer crust is rejected in breaking up theto their size The largest size is 2 by 3-1/2 inches and is called ”lu,” an interenerators is 3/8 by 1-1/4 inches and called ”nut,”

and the finely crushed pieces for use in still other types of generators are 1/12 by 1/4 inch in size and are called ”quarter” Instructions as to the size best suited to different generators are furnished by the makers of those instruht sheet steel dru 100 pounds each The Union Carbide Co under patents, manufactures and distributes the supply of calcium carbide for the entire United States Plants for this ara Falls, New York, and Sault Ste Marie, Michigan This company maintains a system of warehouses in e stocks of all sizes are carried

The National Board of Fire Underwriters gives the following rules for the storage of carbide:

Calcium carbide in quantities not to exceed six hundred pounds es not to exceed one hundred pounds each, inside insured property, provided that the place of storage be dry, waterproof and well ventilated and also provided that all but one of the packages in any one building shall be sealed and that seals shall not be broken so long as there is carbide in excess of one pound in any other unsealed package in the building

Calcium carbide in quantities in excess of six hundred pounds s, used exclusively for the storage of calcius shall be constructed to be dry, waterproof and well ventilated

_Properties of Acetylene_--This gas is coen by weight and is classed with natural gas, petroleuhest percentage of carbon known to exist in any coaseous carbon Carbon is the fuel that is used in all forms of combustion and is present in all fuels from whatever source or in whatever forases and is able to give to the torch flahest temperature of any flaas, possessed of a peculiar and penetrating odor The least trace in the air of a room is easily noticed, and if this odor is detected about an apparatus in operation, it is certain to indicate a leakage of gas through faulty piping, open valves, broken hose or otherwise This leakagewith the work to be done

All gases which burn in air will, when nition, produce more or less violent explosions, if fired To this rule acetylene is no exception One measure of acetylene and twelve and one-half of air are required for complete combustion; this is therefore the proportion for the most perfect explosion This is not the only possible mixture that will explode, for all proportions from three to thirty per cent of acetylene in air will explode withpoint of acetylene is lower than that of coal gas, being about 900 degrees Fahrenheit as against eleven hundred degrees for coal gas The gas issuing frohted cigar

It is still further true that acetylene, at soreater than normal, has under most favorable conditions for the effect, been found to explode; yet it may be stated with perfect confidence that under no circumstances has anyone ever secured an explosion in it when subjected to pressures not exceeding fifteen pounds to the square inch

Although not exploded by the application of high heat, acetylene is injured by such treath heat, into other coas, wasting it and polluting the rest by the introduction of substances which do not belong there These co it to burn with a persistent smoky flame and with the deposit of objectionable tarry substances Where the gas is generated without undue rise of temperature these difficulties are avoided

_Purification of Acetylene_--Ias are caused by impurities in the calcium carbide from which it is eneration Impurities from the material will be considered first

Impurities in the carbide may be further divided into two classes: those which exert no action on water and those which act with the water to throw off other gaseous products which remain in the acetylene Those impurities which exert no action on the water consist of coke that has not been changed in the furnace and sand and some other substances which are harmless except that they increase the ash left after the acetylene has been generated

An analysis of the gas coenerator is as follows:

Per cent Acetylene9936 Oxygen08 Nitrogen11 Hydrogen06 Sulphuretted Hydrogen17 Phosphoretted Hydrogen04 Ammonia10 Silicon Hydride03 Carbon Monoxide01 Methane04

The oxygen, nitrogen, hydrogen, methane and carbon monoxide are either harlected The phosphoretted hydrogen and silicon hydride are self-inflaases when exposed to the air, but their quantity is so very small that this possibility en are alenerator The surest way to avoid ienerator and the carbide of American manufacture is now so pure that it never causes trouble

The first and as is subjected is its passage through the body of water in the generator as it bubbles to the top It is then filtered through felt to remove the solid particles of lias

Further purification to reen and phosphorus containing compounds is accomplished by chemical means If this is considered necessary it can be easily acco apparatus which can be attached to any generator or inserted between the generator and torch outlets The following mixtures have been used

”_Heratol,_” a solution of chromic acid or sulphuric acid absorbed in porous earth

”_Acagine,_” apoith fifteen per cent of lead chro powder and hydroxide of lihteen to twenty per cent of active chlorine

”_Frankoline,_” ahydrochloric acid absorbed in infusorial earth