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Are you worried by any question in Engineering or the Mechanic Arts? Put the question into writing and mail it to the Consulting Department, TECHNICAL WORLD MAGAZINE. We have made arrangements with the American School of Correspondence to have all such questions answered by members of its staff of Instructors. If the question asked is of general interest, the answer will be published in the magasine. If of only personal interest, the answer will bu sont by mail, provided a stamped and addressed envelope is enclosed with the question. Requests for information as to where desired articles can be purchased will also be cheerfully answered,

Soldering Aluminum

grayish white powder. If the material is What is a good method of soldering alu- weighed before and after the treatment, minum?–J. T. K.

the loss in weight will be the amount of Difficulty in soldering aluminum vegetable fiber present. This method, arises from the fact that an oxide forms however, can be used with only certain on the surface of the heated metal. The classes of goods, and is not as accurate or trouble may be overcome by making a

satisfactory as the following method: solder of tin (four parts) and zinc (one

Weigh carefully a small piece of matepart), with stearic acid as a flux. Coat

rial and boil it for four or five minutes in the aluminum with this mixture, moving

a four per cent solution of caustic soda. the copper bit back and forth. The film At the end of this period the wool will of oxide can then be cleaned off and the

be completely dissolved by the caustic coated surface easily soldered.

soda ; and if the weight of the dried residual material is subtracted from the original weight of the cloth, the loss will

represent the weight of wool or animal Separating Cotton and Wool

fiber present. How can cotton and wool, mixed together in a piece of cloth, be separated ?-S. H.

Arc Crucible Furnace on A. C. There are two methods of separating

Incandescent Circuits wool and cotton, which are based on the

1. Would you please let me know if it is action of acids and alkalies on cotton and possible to use an experimental arc crucible wool. Acids completely destroy cotton furnace on the alternating incandescent circuits or vegetable fiber, with little, if any, de

used in the residence parts of the city? structive action on wool; while alkalies

2. Also please let me know if it is necessary

to use any resistance coils, and the best way will destroy wool or animal fibers and lo wire for the furnace. - B.R. R. have no destructive action on cotton. If

1. A small furnace could undoubtedly a cloth containing both cotton and wool is saturated with dilute sulphuric acid, and

be operated from the lighting circuit with dried, without washing, at a temperature

entire satisfaction. of 100° C., and then rubbed briskly be- 2. It would probably be better to use tween the hands, the cotton, which has a resistance-or, better still, a reactance become carbonized, will fall out as a —for regulating the current. The best Mention Technical World Magazine


When you speak of a “ten-cent cigar,” you mean a cigar that costs you ten cents.

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him :

The same cigar is to the manufacturer a' '$40 per M.," or 4c. cigar, to the jobber a “$50 per M.," or 5c. cigar, and to the retailer a ''$60 per M.," or 6c. cigar.

Intrinsically that cigar is worth as much when the manufacturer appraises it at $40 per M. as it is when the retailer hands it over his counter as a "ten-cent straight. The difference between 4c. and 10c. is what it costs to get the cigar from the manufacturer to you along the old-fashioned trade turnpike with three coll gates.

Now, suppose you go to the maker of your cigars and say to

“Sell me my cigars at wholesale and I'll take them home myself across lots."

"Oh, no," he will reply, "that wouldn't be fair to the retailer who has bought my cigars to sell at retail price.'

I am a maker of cigars who has never sold a cigar to a jobber or retailer to sell again. Hence I am under no obligation to "the trade. I invite the patronage of the man who objects to paying for the privilege of allowing a retailer to sell him a cigar-who wants to buy his cigars at cost, without the arbitrarily added expenses of the jobber and retailer. To prove that I actually do sell my cigars at wholesale prices I offer them under following conditions:

MY OFFER IS:-1 will, upon request, send one hundred Shivers' Panatela Cigars on approval to a reader of


Panatela The Technical World, express prepaid. He may smoke ten cigars and return the remaining ninety at my expense if he is not pleasd with them; if he is pleased, and keeps them, he agrees to remit the price, $5.00, within ten days.

The fillers of these cigars are Clear Havana, of good quality-not only clear, but long, clean Havana - no shorts or cuttings are used. They are hand made by the best of workmen. The making has much to do with the smoking qualities of a cigar. The wrappers are genuine Sumatra.

In ordering please enclose business card or give personal reference, and state whether mild, medium or strong cigars are desired.

HERBERT D. SHIVERS, 913 Filbert Street, Philadelphia, Pa.


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3. An arrangement for ringing either one of two bells selectively from one push

button is shown in Fig. 4, in which P hlilc represents the push, C the battery, and

B and B'the bells. S is a single-pole,

double-throw switch; when it is thrown simultaneously from one push. These on contact 1, if P is pushed, bell B will two methods are shown in Figs. 2 and 3, ring. When the switch is on contact 2, in which B and B' represent the bells, if P is pushed, bell B' will ring.

Fig. 2.






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City and State......


Mention Technical IVorld Magazine




Cyclopedia of Modern Shop Practico. А date, representing the latest and best of Practical Manual of the Best Modern American Methods in all Lines of Shop Work and Allied Branches of

American methods, and being based on Mechanical Industry. Four Volumes; 3,000 pages, 7 by 10 inches. Illustrated with over 2,500 half-tones and

the most careful study, by acknowledged explanatory diagrams. Indexed. Published by the authorities, of actual shop needs and conAmerican Tochnical Society, Chicago, Ill.

ditions. To read it, means to qualify for

the very highest kind of service. It THERE can be no such thing as “dry rot” means becoming intimately acquainted for any workman fortunate enough to with the best in American practice; it own this set of books. Be he foreman, means mastering those methods which journeyman mechanic, or apprentice, he have been the basis of America's material will find in it a key to progress and ad- success in competition with other nations, vancement. The CYCLOPEDIA OF MODERN and which have made the American SHOP PRACTICE was conceived in the workingman the most intelligent, the spirit of helpfulness, and has been pre- most efficient, and the best-paid workingpared throughout with a view to meeting man in the world. The appearance of the daily needs of the workingman as such a work from the press is in itself they arise under the conditions of actual the rendering of a public service worthy practice. And most admirably it fulfills of generous support; and we predict for its mission. To most men, a cyclopedia the CYCLOPEDIA OF MODERN SHOP PRAClooks formidable ; but to master this one, TICE, as its intrinsic merits become it will be found, is well within the power known, an increasing popularity, not only of the average wage-earner, and does not

among workmen who are ambitious to require the elaborate formulze of the make the best of their opportunities, but mathematician or the costly training of also among employers who take any apthe technical school. If knotty problems preciative interest in the welfare of their arise or obscurities are found, the Con- employees. sulting Privilege—which is given free for The field covered by the work is not one year to each purchaser—will instant- confined, however, within the walls of the ly bring the assistance of experts to clear “shop,” so called, but takes in almost away all difficulties.

every branch connected directly or indiThis invaluable work stands head and rectly with machine shop practice, such shoulders above every other on Shop as the designing of machinery, forging, Practice which has yet appeared, not only pattern-making, foundry work, tool-makin its breadth and variety of scope, con- ing, sheet metal work, tinsmithing, boiler venience of arrangement, and adequacy work, making of shop drawings, etc. The of treatment of each topic, but also in its reader is put abreast of the very latest thorough adaptation to meeting the wants progress by such chapters as those on the and solving the problems that are con- Turbine, Gas and Oil Engines, Automotinually arising in actual practice in the biles, Elevators, Electric Wiring and shop. It is, moreover, thoroughly up-to- Machinery, etc.

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