Read Ebook: The Art of Lead Burning A practical treatise explaining the apparatus and processes. by Fay C H

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CHAPTER. PAGE.

INTRODUCTION.

In compiling a treatise on the subject of lead burning too much stress cannot be laid upon the fact that the greatest care must be taken to observe the smallest details and to follow carefully every suggestion in regard to safety. I am aware of the responsibility resting upon me in placing this article into hundreds of hands, comparatively ignorant of the danger involved in handling so much hydrogen, without thoroughly instructing them in detail as to its use. I may be excused, therefore, if, for that reason, some of the explanations are so simple as to seem ridiculous; but my aim is to present to the trade a treatise that can be relied upon to be free from theory that has not been thoroughly tried and tested, so that the beginner can be sure that, if he follows directions as printed, nothing but satisfaction to him can result.

I cannot too strongly recommend that the beginner study the chapter on hydrogen gas until the main points are memorized and clearly understood. The experiments should be performed and the result carefully noted for future reference before attempting to use the generator. It is time well spent to master the technical parts thoroughly before attempting the mechanical part. Then when a man takes up the mechanical he will do so with an intelligent understanding of what he is doing, and any little trouble which may then arise can be quickly overcome.

Another thing to be observed is to avoid nervousness. A nervous person cannot do this work with any degree of satisfaction, as it requires a cool head and a steady hand and a vast amount of patience to burn the upright and inverted seams.

Lead Burning Explained.

Lead burning is the process of fusing two pieces of lead together without the use of solder. The process consists in melting the edges together, a drop at a time, and when done with hydrogen gas and the blow pipe is called the "autogenous process." Lead can be fused with gasoline or illuminating gas by the use of the compound blow pipe; but, as ordinary gases give an oxidizing flame and require a flux, it is not considered a practical method.

Lead is used extensively in lining tanks made to contain pickle dips, hot cyanide solution, storage batteries, acid tanks for manufacturing jewelry and water closet tanks, as water in many cases contains large quantities of lime and other deposits which rapidly destroy the solder used on copper linings. Tanks used for the above purposes must be lined with lead and the seams burned, as acids attack the tin in solders and destroy them. The demand for the work is rapidly increasing where it is introduced. I have demonstrated to many manufacturers that this is the cheapest method known, as it gives a permanent solution of the problem how to keep a chemical tank tight.

Method of Making Lead Lined Tanks.

The most common method resorted to in many large factories is to make the tanks out of very heavy cypress lumber, free from any knots or blemishes. The joints are carefully dovetailed and fitted together, and long bolts are used to draw the joints and keep them from leaking. Usually it takes from three to four days to complete one small tank, only to have it leak in a few months; whereas the same tank can be built in a few hours of any cheap lumber, and then, when it is lined with lead of a proper thickness and the seams burned it will usually last for an indefinite period, thereby saving floors and, many times, costly plating solutions.

The most common argument put forth by manufacturers is that the bottoms of lead lined tanks are soon cut out, owing to dropping sharp pieces of metal into them. This difficulty can be best overcome by placing a slatted bottom of wood in the tank, holding the same in place with strips of sheet lead, one end of which has been previously burned to the bottom of the tank. These strips are to be brought up through the slats and then bent over the top of them. This will keep the wood from floating, and is the only practical way to do it, as the false bottoms soon decay, and can be easily removed and replaced by simply bending back the strips of lead.

General Remarks.

Soft solder, as referred to here, means solder that melts at a temperature of 300 degrees or less, and is so called because of the low heat required to fuse the solder. It is used almost exclusively on the quick melting metals and compositions, such as block tin pipes and Britannia metal. It is also used by pattern makers in soldering white metal, as it requires but very little heat to sweat it through heavy articles. It should not be used to join any pipes which convey hot water or other hot liquids, as it is readily acted upon and destroyed.

The chapters on blow pipe work, also on bar work, will alone turn many dollars into the pockets of the plumbers who have courage and ambition to acquire this line of work. Many times small leaks occur in difficult places that can be readily repaired by the use of the blow pipe and a common candle.

The lining of bars with Britannia metal is coming more and more into general practice, and it usually requires a specialist in this line to do the work. The soldering of this metal with a blow pipe and an alcohol torch is an easy matter, and is described in a special chapter.

There is no reason why this work should not be done by a plumber, particularly in small cities and towns, and to aid such as have not had the opportunity to familiarize themselves with such work I append such diagrams as may seem useful and necessary.

The requirements of a hydrogen generator for lead burning are that it should be safe, economical and automatic in its action. It must be so constructed that it will generate gas enough to keep the supply constant, and deliver it at sufficient pressure to keep the flame steady. It must also be provided with a combination fire trap and scrubbing cup. This will prevent the explosion of the generator by firing the gas in the hose. This trap must be partly filled with a solution of blue vitriol to act as a precipitation cup.

The chief danger with an apparatus of this sort is its liability to accident by the careless use of the gas, and, as a mixture of hydrogen and air is very explosive, great care must be taken to exhaust all the air in the generator and tubes before attempting to light the gas at the blow pipe. The only way to make sure that the air is exhausted is to test the gas, as described under the head of "The Flame and Its Management."

A Few Cautions.

It is a very sensible idea to keep spectators away from the generator, as they are very apt to strike matches or tread on the tubes, in spite of warnings to be cautious, for if there should be a leak, even so slight as to be hardly detected, it would cause a violent explosion, and as hydrogen is both odorless and colorless, this could easily happen without being noticed. This is probably the origin of the apparent secrecy with which a lead burner usually surrounds himself.

If an explosion should occur in the tubes and they should catch fire, the operator must have presence of mind enough to reach the gas cock on the generator and close it. If gas explodes in the generator, all that can be done is to dodge the flying pieces and make a new generator. If such an incident should occur and vitriol should spatter on the person doing the work, or his assistant, a solution of bicarbonate of soda or common washing soda should be at once applied to the wounds. If that cannot be procured, grease or oil of some kind should be used without delay, rubbing it on the spots where the acid burns, and this will neutralize the acid and so prevent it doing further damage. There should be no trouble of this sort in the hands of a careful workman. The watchword should be, "Test the gas before using." If this is done, explosions will never occur.

This element was discovered by Cavendish in 1766, and was called by him inflammable air. The name hydrogen is derived from two Greek words, one signifying "water" and the other "to generate," on account of its forming water when burnt. It occurs in its free state in the bases of volcanoes, and by the aid of the spectroscope has been detected in the sun and stars. It chiefly exists in combination with oxygen as water, and is an important constituent of all vegetable and animal substances.

Hydrogen is obtained by the decomposition of water in various ways. On a large scale, nearly pure hydrogen may be prepared by passing steam over charcoal, or coke, heated to a dull redness. If the temperature be kept sufficiently low hydrogen and carbon dioxide will be the sole products, and the latter may be removed by causing it to traverse a vessel filled with slaked lime, but if the temperature be allowed to rise too high, or an excess of air be admitted, carbon monoxide is also produced, and cannot be removed from the mixture.

Pure hydrogen is a colorless, odorless, transparent and tasteless gas, and has never been liquefied. It is very slightly soluble in water. It is the lightest of all known bodies and is not poisonous, although it cannot support life, and if mixed with a certain proportion of oxygen it can be breathed for a considerable length of time without inconvenience. It is highly inflammable, and burns in the air with an almost colorless, nonluminous flame, forming water. A burning taper is extinguished when plunged into hydrogen, and all bodies which burn in the air are incapable of burning in hydrogen.

Hydrogen does not spontaneously enter into reaction with any of the elements, although it has a powerful affinity for several of them. Thus, when hydrogen and oxygen are mixed nothing occurs, but if a lighted splint is introduced a violent explosion ensues, water being produced. Similarly chlorine and hydrogen are without action upon each other in the dark, but if the mixture is exposed to a bright light, or if heated by the passage of an electric spark, the gases are at once combined with explosive violence, forming hydrochloric acid.

Hydrogen is usually prepared by the action of zinc or iron on a solution of hydrochloric or sulphuric acid. All metals which decompose water when heated readily furnish hydrogen, on treatment with hydrochloric or sulphuric acid. Many other metals enter more or less readily into reaction with these acids. Also, many other acids than sulphuric or hydrochloric acids may be used, but none acts so quickly. In all cases the action consists of the displacement of the hydrogen of the acid by the metal employed, and if the acid is not one which can enter into reaction with the displaced hydrogen, the latter is also evolved as gas.

If pure gas is required it is necessary to employ pure zinc or iron, as the impurities in the ordinary metal communicate an extremely disagreeable odor to the gas.

The pure gas is not absolutely essential for lead burning, and owing to their being much cheaper, and also on account of their increased quickness of action, the commercial qualities of sulphuric acid and zinc are employed in the generator described.

The commercial zinc is known as spelter and is sold in pigs or blocks, which are easily broken into fragments, like stove coal, with a heavy hammer. The commercial sulphuric acid is known as oil of vitriol and is sold by the pound. The acid cannot be employed in its pure state, but must be reduced with water in the proportion of one part of acid to seven parts of warm water. They must be mixed by adding the acid slowly to the water; never the water to the acid. The combination of acid and water enters at once into reaction and always generates heat, and the result of adding water to acid would be small explosions. There would be danger of the acid flying on one's clothes or into the eyes. The mixture should never be stronger than six parts of water to one of acid.

The beginner will observe from the above that the generator cannot be crowded by making the acid solution strong. Hydrogen is a peculiar gas and also a dangerous one for one ignorant of its peculiarities to experiment with, and in order to thoroughly understand it the following experiments should be demonstrated, which can be done with little expense. The beginner should note the result of each experiment as demonstrated, and carefully commit the same to memory for future reference.

Experiment 1.

Experiment 2.

Experiment 3.

Experiment 4.

The construction of the generator is the first step in the mechanical part of the business, and to simplify this a complete set of reference drawings has been constructed and is herewith given. The assembling of the parts should be clear, with the assistance of the perspective drawing of the completed apparatus, and any mechanic of ordinary ability should be able to construct this generator without any trouble. The following bill of material should first be purchased:

One 7/8 -inch whitewood board 10 inches wide and 8 feet 6 inches long.

One 1/2 -inch whitewood board 12 inches wide and 4 feet 6 inches long.

One piece of 6-pound sheet lead 3 feet wide and 6 feet 6 inches long.

Three 1/8 -inch female hose end gas cocks.

One piece of 1/8 -inch brass tubing 2 feet long.

One foot of 1/4 -inch lead pipe.

One 4-inch charging screw.

One 1 1/4 -inch cleaning screw.

Making the Charging and Cleaning Screws.

Building the Frame.

Now fit the sheet lead. Six-pound is plenty heavy for this generator and will last a lifetime. Cut it as shown in Fig. 8, A and B. Form the lead so that the seams when finished will come on the outside, as in case of a leak in a seam it can then be easily repaired by removing one of the boards. The projecting edges of lead should be dressed over the edges of the top to protect the wood from the acid, but do not fasten them, as the tanks will have to be removed and the seams burned.

This is one of the most particular parts of the apparatus, as this is where the automatic action comes in, and great care must be taken in cutting these holes not to have any of them come closer to the perforated bottom than 1 inch. If this were not observed the acid would be constantly in contact with the zinc, and would rapidly get up pressure of gas sufficient to blow acid out of the upper tank, and the extra gas would escape through the acid supply pipe in blows. In fact, it would make the generator useless. This is the trouble with the French apparatus. The acid, having no place to expand in, is constantly coming into contact with the zinc, and unless the gas is being used as fast as generated it will blow acid out of the acid holder, making a bad mess, besides being very wasteful.

In towns supplied with illuminating gas it is a comparatively simple operation to burn the lead lining for the generator, but for the convenience of those who cannot obtain gas it is necessary to give some method by which the generator can be burned. The method described will answer for illuminating gas as well as for gasoline.

To generate gas from gasoline is a simple operation. To do this, take a common 1-gallon oil can, remove the top of can screw and punch a 1/4 -inch hole in the center of it. Then make a tube of tin that will pass through this hole, sufficiently long to extend half way to the bottom and project 2 inches outside of can screw, and solder this tube in place. This projecting tube is for the purpose of connecting to the air holder. Remove the spout of the can and replace it with one to which the hose can be connected. Now fill the can two-thirds full of gasoline, but not full enough to cover the gas outlet, else it would be likely to force gasoline out instead of gas.

Air Holders.

Different lead burners have different views on this subject. Some prefer the bellows, with a contained air holder; some the air holder built like a gasometer, while others use an air holder similar to the generator in construction. These all have their advantages. For my part, I own and use all three.

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