Part 3 (1/2)

Oxygen is prepared in the laboratory by variousof chloride of li of chlorate of potash, and the separation of water into its elee of an electric current While the last process is used on a large scale in commercial work, the others are not practical for work other than that of an experias is a colorless, odorless, tasteless eleen when measured by volume under the same teen reh it turns to a liquid when compressed to 4,400 pounds to the square inch and at a teen unites with alreat heat andflaas if the co on the ht red and quickly plunged into a jar containing this gas, the ill burn aith a dazzling light and be entirely consumed except for the en is used in oxy-acetylene cutting of steel

The coen with other substances does not necessarily cause great heat, in fact the coe of temperature can not be noticed An example of this slow combustion, or oxidation, is found in the conversion of iron into rust as the as The respiration of hus and animals is a form of slow coeneral rule that the process of oxidation takes place with increasing rapidity as the te acted upon rises

Iron and steel at a red heat oxidize rapidly with the fore to the en and nitrogen with traces of carbonic acid gas and water vapor Twenty-one per cent of the air, by volu seventy-nine per cent is the inactive gas, nitrogen But for the presence of the nitrogen, which deadens the action of the other gas, combustion would take place at a destructive rate and be beyond huases exist simply as a mixture to form the air and are not chemically combined It is therefore a comparatively simple matter to separate them with the processes now available

_Water_--Water is a co coen to one voluases be separated from each other and then allowed to mix in these proportions they unite with explosive violence and forases by any one of severalabout this separation

[Illustration: Figure 7--Obtaining Oxygen by Electrolysis]

The easiest way to separate water into its two parts is by the process called electrolysis (Figure 7) Water, hich has been h the walls of which enter the platinum tipped ends of two electrical conductors, one positive and the other negative

Tubes are placed directly above these wire ter over each electrode and separated froe of an electric current froas rise froas that coen and that fro almost pure if the work is properly conducted This en

_The Liquid Air Process_--While several of the foregoing en are successful as far as this result is concerned, they are not profitable froen froh state of perfection and is now supplying aIt is known as the Linde process and the gas is distributed by the Linde Air Products Coe cities of the country

The air is first liquefied by coen collected The air is purified and then coned for this purpose until it reaches a pressure of about 3,000 pounds to the square inch The large a the process of cohly compressed air is then dried and the temperature further reduced by other coolers

The next point in the separation is that at which the air is introduced into an apparatus called an interchanger and is allowed to escape through a valve, causing it to turn to a liquid This liquid air is sprayed onto plates and as it falls, the nitrogen return to its gaseous state and leaves the oxygen to run to the bottoen is then allowed to return to a gas and is stored in large gasoe tanks and compressed to approximately 1,800 pounds to the square inch, under which pressure it is passed into steel cylinders and en is guaranteed to be ninety-seven per cent pure

Another process, known as the Hildebrandt process, is co into use in this country It is a later process and is used in Gerreater extent than the Linde process The Superior Oxygen Co has secured the Aen Cylinders_--Two sizes of cylinders are in use, one containing 100 cubic feet of gas when it is at at 250 cubic feet under similar conditions The cylinders are made from one piece of steel and are without seams These containers are tested at double the pressure of the gas contained to insure safety while handling

One hundred cubic feet of oxygen weighs nearly nine pounds (8921), and therefore the cylinders eigh practically nine pounds , if of the 100 cubic feet size The large cylinders weigh about eighteen and one-quarter poundsapproximately 212 pounds eives the nu in the cylinders according to various gauge pressures froiven are not exactly correct as this would necessitate lengthy calculations which would not h difference to affect the practical usefulness of the table:

Cylinder of 100 Cu Ft Capacity at 68 Fahr

Gauge Volu

1800 100 700 39 1620 90 500 28 1440 80 300 17 1260 70 100 6 1080 60 18 1 900 50 9 1/2

Cylinder of 250 Cu Ft Capacity at 68 Fahr

Gauge Volu

1800 250 700 97 1620 225 500 70 1440 200 300 42 1260 175 100 15 1080 150 18 8 900 125 9 1-1/4

The teree, the pressure increasing with a rise in te with a fall in temperature The variation for a 100 cubic foot cylinder at various te tabulation:

At 150 Fahr 2090 pounds

At 100 Fahr 1912 pounds

At 80 Fahr 1844 pounds