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they had completed the job before them,

Relief of Street Congestion it being arranged that they should get The down-town streets of Chicago are through so that the miners could begin alınost continually blocked by the wagons promptly at 4 o'clock in the afternoon. of teamsters who are carrying away the

A total of about 850 men were em dirt excavated in constructing the baseployed in the tunnel construction, about ments and foundations of the great sky600 additional men being employed in

scrapers and other large buildings which the office force, in the hauling of cement, are always in process of construction at gravel, and other materials, and in the various points inside the loop. This concarrying away of the excavated dirt. For

gestion the company hopes to relieve by the purpose of expeditiously getting the

contracting to remove through its tunnels excavated dirt to the elevator houses,

the excavated dirt and other debris where where it was lifted to the street level, 900

old buildings are torn down. That this little tram cars were used. These tram

plan is more than a mere theory, is shown by the fact that the company has recently signed contracts to do this work in the case of two large buildings now in course of erection in the down-town district.

It also hopes to be able to relieve, the congestion still further by conveying to the site of new buildings all or most of the material necessary in their construction. How great a relief it would be to have new buildings go up on their own ground, with no blocking of sidewalks and streets by loading and unloading wagons, every citizen of Chicago knows without the telling.

These are some of the principal ways in which the company expects to make its large investment profitable, at the same time leaving the surface of the streets free for the use and transportation of the 'people. If this is as yet chiefly an un

realized dream, unanimous Chicago will TUNNEL AT STATE AND LAKE STREETS, LOOKING

hope to wake up one day to find that the cars were only four feet long and twenty

dream has been largely fulfilled. inches wide, and Chief Engineer Jackson

Electric Power believes that largely because of the smallness of these cars there was no delay in Power for the operation of the tunnel getting the immense quantity of dirt out railroad will be furnished by a generating of the way of the concrete gang who plant capable of producing 5.000 horsefollowed so closely behind the miners. power, for the construction of which the

The little cars, loaded with dirt, were company is now about to let the contract. lifted by elevators to the mouths of the Direct current at 250 volts will be used, elevator shafts, where they were dumped the rails acting as a return. Power for into waiting wagons, and then promptly experimental purposes has been furnished sent back down the shafts for fresh loads. by the Chicago Edison Company. The So perfect were all the arrangements and trains will attain a speed of between fifso rapidly was the work done, that in ten teen and twenty miles an hour. and a half months of actual work, no less The original purpose of building the than twelve miles of tunnel was com tunnels as conduits for the cables and pleted, and that without any accident to wires of the Illinois Telephone & Teleworkmen, or, on the testimony of Chief graph Company has not been lost sight Engineer Jackson, a single complaint of. These wires-now serving more than from a pedestrian or property owner. 5,000 subscribers—are carried along the

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TORTH.

side walls of the tunnels, and there is plenty of space left for many times that number, the ultimate aim of the company being to supply at least 100,000 separate automatic telephone stations.

The company's plans include the extension of its present twenty miles of tunnels to nearly sixty miles, the territory to be tapped reaching from 71st street on the South Side, to Kedzie avenue on the West Side, and to Fullerton avenue

on the North Side, the tunnels on the outskirts being reduced in size and adapted only to the carrying of telephone and other wires.

The chief interest, however, in the plans of the company, so far as the general public is concerned, lies in the present effort to relieve the congestion of the down-town streets by carrying freight and other commodities far down underneath the surface of the streets.

The Softening of Water for Steam-Raising Purposes

Essential Features and Comparative Values of the Continuous and

Intermittent Systems

By WALTER H, GREEN

Secretary, Kennicott Water Softener Company

10 one who looks through the cur

rent engineering journals, it is unnecessary to say that there is

at present a great deal of interest being displayed in the subject of water treatment. The railroad papers of the United States may especially be noted as giving more space to this than to any other one topic. The awakening of interest in this country is many years behind the appreciation of the question in Europe, where it has developed to a point sufficient to establish certain principles. It would be well for some of the many who are rushing into the business of water treatment in this country, if they would investigate the conditions of the problem somewhat carefully before investing their time and money in schemes that are predestined to fail-or, perhaps I should say,

to fail again. In view of what has occurred in other fields, it is not surprising that all sorts of water-softening devices should now be thrust upon the market. The inventor-chronic and otherwise—sees the demand, and hears of the success others have made. The field is invitingly easy; all you have to do is to get the hard water into something, stir something into it, and the deed is done. The first water softener with which the writer had to do was built upon that principle, and it cost the company with which he was connected good many thousand dollars to install the tanks, etc., and a couple of hundred to clear the ground of them about a year and a half later. There is now in operation at this plant a water softener which occupies a ground space fourteen feet by eleven feet, and which

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TYPICAL WATER-SOFTENING PLANT INSTALLED FOR RAILROAD SERVICE,

does what was hoped to be accomplished nesium, which at boiling temperatures with four other tanks covering 2,600 decompose with liberation of acid; and at square feet of ground.

times by organic matter. The use of conPractically all of the advance made densed water, or water highly charged in the United States has been made in with oxygen, has also sometimes given the last six years; and, while this is not a rise to similar trouble. Different causes very long time, it has been enough to have been assigned for foaming, but in advance the art beyond foreign practice most cases it is due to soluble matter, in all points except the number of plants such as salts of sodium and potassium, in operation. That this is true is evidenced by the failure on the part of practically all the softeners of foreign origin to succeed on this side in competition with the American product. In fact, only one company exploiting such foreign devices is at the present time showing much sign of life, and this one has not been very long in the field. A great many patents have been taken out in connection with water-softening apparatus within the past five years. Again, as in other lines, some of these are good and of real value; most are impracticable in themselves or because of competition ; but altogether they so cover up the field

INUD that about all to be looked for now is in the way of minor improvements tending to produce more satisfactory or economical results.

It is not the intention in this article to consider the softening of water except

Section of Water-SOFTENING Tower. for steam-raising purposes, although is of value in many lines of industry. For concentrating in the boiler. Inasmuch as instance, the writer knows of one laun scaling is due chiefly to compounds of dry where a softener costing about $6,000 calcium and magnesium present in the is saving $300 to $400 per month in the

water, practical softening consists largely soap bill. At a woolen mill the amount in the removal of these. The salts of of soap used in scouring has been re

calcium and magnesium found in water duced over fifty per cent and a consid are chiefly the bicarbonates, sulphates, erable saving in dyes is made, while the and chlorides. Other compounds are ocgoods are more satisfactory in color and casionally present, but usually in very feel.

small amount; and treatment for those Difficulties to be Overcome

noted above will take care of all. Ever since steam has been raised for

Softening Agents power purposes, and increasingly with the use of higher pressures, the use of It is not at all difficult to find subnatural waters has been accompanied stances which, when added to water conwith certain troubles, the more promi- taining these salts, will react with them nent of which have been scaling, cor to form new compounds so much less rosion, and foaming. Investigation has soluble in water that the greater part of shown that scaling is caused chiefly by the calcium and magnesium is thrown out the salts of calcium and magnesium in in solid form. Experience has shown solution in the water, and by silica, mat that of all such substances common lime ter in suspension also contributing when and sodium carbonate are at once the best present. Corrosion is caused by free acid and cheapest; and these are what are in the feed water, this being common used in practically all cases here and

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The function of the lime is to remove simple subtraction. To illustrate: When the carbonates. Properly speaking, these sodium carbonate reacts with calcium sulshould be called "bicarbonates," indicat phate, an interchange takes place in which ing an excess of carbonic acid present are formed calcium carbonate and sodium over what is necessary to form the nor sulphate. As all sodium salts are quite mal carbonate. When lime is brought in soluble in water, this sodium sulphate contact with such bicarbonates, the excess does not deposit and under certain cirof acid present combines with the lime, cumstances must be considered. and the normal carbonate is produced. In Many attempts have been made, and this it should be noted that the added lime some are still being made, to soften water subtracts a part from the compound of containing small amounts of carbonate of lime (or magnesium) previously in the lime and magnesia by the use of soda ash water, both portions subsequently exist alone. A moment's consideration will ing in the same form as normal carbon disclose why these attempts fail. Soda

[graphic]

WATER-SOFTENING PLANT. One of the four systems erected for the Chicago, St. Paul, Minneapolis & Omaha Railway by the Tweeddale Water

Softening Company, Chicago, Ill.

ates. These normal carbonates are sol ash brought into such water will form the uble in water only to the extent of about carbonates from the sulphates, etc., presthree grains per gallon, and any excess ent; but, instead of precipitating, these formed above that amount deposits as a carbonates unite with the free carbonic solid. It should be said here that, in acid spoken of above, and remain in soluaddition to the amount of lime needed tion as bicarbonates, with the net result for the purpose indicated above, a fur that, instead of the water being softened, ther amount must be used, as in all nat the total solids in the water have simply ural waters there exists a greater or less been increased by the amount of soda ashi amount of what is called free carbonic added. acid. This carbonic acid is simply in solu Experience having shown what are the tion, not combined with anything; and best reagents for water softening, the lime to combine with it is needed before questions that arise are: How much of the other action can take place.

these are needed, and how are they to be The carbonate of soda, commonly used applied? The quantities to be used, of in the form known as soda ash, reacts course, vary with different waters, and with the sulphates and chlorides. This must be determined for each one by analaction is not exactly like that of the lime, ysis. Lake Michigan water treated in a there being a transfer with the formation softener of the continuous type, requires of two different substances instead of a about one pound of lime and one-third

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