Invention of the Practicable Balloon Portable Hydrogen Gas Generators

Professor Thaddeus Lowe's Balloon Gas Generators on the Washington Mall in front of the United States Capitol in Washington D.C. - 1861

(Courtesy of Smithsonian Institute)

Joseph Ferm Collection

National Air and Space Museum of the Smithsonian Institute

War of the Aeronauts, pages 118-121

    The construction of Lowe's first gas generators started with a pair of standard issue army wagons. On each of the wagon's a large wooden tank about eleven feet long by five feet high was constructed. Inside each of the wooden tanks there was a copper liner. Although copper was not entirely resistant to the corrosive elements of the sulfuric acid with which it would come in contact, it proved to be adequate enough to seal the interior of the tank sufficiently in the field. Additionally, the wooden tanks were built with extra strength to withstand the tremendous bursting pressures that developed inside during the chemical reaction that formed the hydrogen.


    On the top of the tank there was a hinged metal plate that allowed the metal filings to be deposited inside. Also on the top, located near the middle, was a funnel-shaped copper pipe where the undiluted sulfuric acid was poured. On the end opposite the filler plate there was a copper "escape" pipe that allowed the hydrogen to flow into a large rubber hose. The rubber parts for the generators were supplied by Goodyear's Rubber, Belting, and Packing Company of Philadelphia.


    The rubber hose lead to a gas purifier, another wooden box with copper hose fittings that contained a solution of lime and water. The purifier served a dual purpose. It was effective in filtering out inert elements in the gas, such as carbonic acid, and also cooled the gas significantly as it escaped the volatile environment inside the generator. Generally, two purifiers were connected one after another between the generator and the envelope. After passing through the second purifier the gas was, "delivered, barely warm, into the balloon."


    When the inflation process was started the hose from the second purifier was inserted directly into the valve of the stretched balloon envelope after "a clear stream of hydrogen" was obtained. A balloon could be inflated in about three hours and fifteen minutes from a single generator. But Lowe discovered that the inflation time could be cut in half when two generators were used to inflate one balloon.


    Supplies for the generators were carried in separate wagons. Four barrels of iron filings each weighing over 800 pounds and 10 glass carboys containing a total of about 40 gallons of sulfuric acid were the primary ingredients for a single inflation. The supply wagons also carried spare rubber hoses, copper pipes, and assorted hardware to maintain the generators in the field. Because of the weight involved, a team of four horses was required to draw each hydrogen generator and supply wagon to an inflation site. The carboys of acid were stored in a separate wagon drawn by two horses.


    Lowe also prescribed a strict method of mixing the metal and acid together. The iron was shoveled through the metal plate on the top of the generator and the acid was poured into a copper funnel. With the tank about one-third filled with iron, five carboys of acid were first poured into the generator. This was followed by a brief waiting period that allowed the gases to expand in the tank and then three more carboys of acid were poured in. According to Lowe, the careful combination of these two elements reduced the possibility of rupturing the wooden tank from the pressure of the rapidly expanding gas.


    Following an inflation, hinged doors were opened at the side of the generator and the decomposed contents of metal acid were raked out onto the ground wherever operations were taking place. Little thought was given to the toxic residue left behind from the generators, giving the Balloon Corps the dubious distinction of being an early contributor to the longstanding problem of military pollution.


    Nonetheless, Lowe was justifiably proud of his accomplishment. He even went as far as to engage a draftsman to render his idea on paper for a formal patent application. Lowe eventually contracted to have twelve generators constructed for the Balloon Corps during the war. Though his patent for the process was never approved, Lowe made certain that the origin of his invention was never in question. The words "Lowe's Balloon Gas Generator" were boldly stenciled on each of the devices constructed for the Balloon Corps.

John Wise's Failure at Inventing Practicable Portable Generators

Military Ballooning during the Early Civil War, pages 76-77

    It is of interest that the generating system proposed by Wise was designed to use the water decomposition process, similar in principle to that employed by the first balloon corps commander in history, Captain Coutelle, sixty-seven years before. Wise added the element of mobility to the chemical principles followed by his predecessor, and thus hoped to produce an apparatus that would be capable of accompanying an army in the field and of producing gas for inflation wherever needed.

    His plan called for a contrivance after the form of a common "wagon boiler," consisting of two eighteen-inch cylindrical retorts, constructed of boiler plate, arranged to contain the oxidizing materials, iron turnings and charcoal. With these retorts was to be mounted a steam generating compartment, with a fire-box attached to furnish heat for both. The steam boiler was connected with the retorts by a stout metal tube. As soon as the oxidizing material should be heated to a white-heat, a stop-cock between the steam box and the retorts would be opened, permitting the steam to pass in and through the heated and decomposing turnings and charcoal. The action of the steam on these materials in white-hot condition would produce a supply of hydrogen, which when cooled would serve for inflation of the balloon. With the whole apparatus mounted on a wagon frame to be drawn by a team of horses, gas could be thus manufactured wherever there should be a supply of fuel for the retorts and steam boiler. Wise planned to have a mobile tender for carrying supplies of water and iron turnings accompany the generator. Since an abundant supply of firewood could be obtained almost anywhere the army might go, Wise believed the problem of replenishing gas in the field would be solved by his plan.

    The plans were submitted to the firm of Morrish, Tasker and Company, expert machinists of Philadelphia, as well as to Dr. John C. Cresson, President of the Franklin Institute, who examined the practical merits of the specifications presented. Wise had calculated that the field generator would produce gas in sufficient volume to inflate his balloon in four hours, or a total of 5,000 cubic feet per hour. But when the experts worked out the figures and details, they found that the materials needed for a single inflation with such an apparatus would amount to at least 7,500 pounds of iron turnings, and 22 cubic feet of water, the latter weighing almost as much as the iron. A generator capable of using this quantity of material would itself weigh more than five tons, in addition to the tender carrying the 7,500 pounds of iron. The machinists also consulted Professor Leslie Rogers and other scientific men, and all agreed that while it was perfectly possible to produce the required amount of hydrogen with the equipment designed, the plan would be "hardly advisable, as the machinery and extra quantities of iron required will be both troublesome and expensive." The figure estimated by Morris, Tasker and Company amounted to $7,000, almost ten times the cost of the balloon. The Topographical Bureau declined to consider the project, which was abandoned as "too expensive."


Military Ballooning during the Early Civil War, pages 247-253

    The problem of keeping the balloons inflated in the field, in sectors not adjacent to commercial sources of gas, had been apparent to all concerned with the aeronautic operations from the first. To remedy this difficulty, Lowe designed a mobile field generator, adapted to an ordinary army wagon frame, capable of accompanying the army into almost any reasonable position. Both Wise and La Mountain had experimented with apparatus working on the water decomposition principle and had failed to produce a practical field generator. Excess weight, size, complicated machinery, and general unwieldy proportions were all unfavorable factors in these earlier attempts. Discarding the unsuccessful methods previously tried by his predecessors, Lowe adopted the sulphuric acid and iron process, which enabled him to design a relatively light, compact, and wholly efficient apparatus, capable of producing sufficient hydrogen to fill a balloon within a few hours after inflation operations were begun. In fact the machine thus produced was the first successful mobile generator ever to accompany an army in the field.

    The Lowe Generator was a comparatively simple apparatus. It consisted of a strong wooden tank, five feet high,  eleven feet long, and of the same width as an ordinary escort wagon, acid-proofed on the inside, and braced on the exterior with strong longitudinal, vertical, and diagonal braces to protect the wooden walls against pressure from the generated gas. For the same purpose, the tank was further strengthened by a series of copper rods, fitted horizontally from side to side on the interior. The sides and ends of the tank were fitted with a series of shelves to facilitate the more even distribution of the iron filings, which were introduced through an eighteen-inch circular opening in the top, called a "manhole." This opening was fitted with a tight cover, opened and closed with a series of strong wing-knobs, and sealed when closed with gas-proof packing. In the top of the tank was also fitted a copper funnel and tube, with a stop-cock. The tube extended vertically into the tank and served to convey the sulphuric acid into contact with the iron and water in the generator. At the forward end, an elbow pipe of copper issued from the top of the tank and served as a connector to the gum hose that carried the newly generated gas to the cooler and purifier. In the rear wall of the tank was cut a tight door or "gateway," fitted and controlled with iron straps and locking keys, to permit drawing off the oxide of iron and other waste material after the gas had been generated. In the wall above the gateway was fixed a brass stop-cock to facilitate the passage of water after the generating process was complete. The tank and all its attached fixtures were mounted on the running gear of an ordinary escort wagon, held firmly in place by a series of iron bars bolted to the wagon frame and turned up at the sides, thus securing the tank to the running gear.

    The cooler and purifier were separate from the generator tank and were connected with it by copper couplers and 6-inch rubber hose. This auxiliary equipment consisted of two stout wooden boxes, treated to make them gas-tight, each containing an inner inverted box with inclined planes over which the gas flowed during the cooling and purifying process. The first box or cooler was filled with water through which the gas passed, flowing over the surfaces of the inclined planes of the inner inverted box. The gas, after passing through this water cooling process, escaped through a copper coupler into a second gum hose which conveyed it into the purifier, which was charged with lime and water. The lime solution absorbed the carbonic acid and other extraneous gases, thus purifying the hydrogen before it was fed into the balloon through a 12-inch connecting hose and valve. A hand force pump was often connected between the purifier and the balloon to facilitate inflation.

    The process for making gas with this apparatus was simple and rapid. It required, however, a thorough knowledge of the proper mixture of materials, and careful handling of the equipment. For a single inflation, four barrels of fine iron filings or borings, each weighing approximately 834 pounds, or a total of approximately 3,300 pounds, were introduced into the tank through the manhole at the top. This material was spread as evenly as possible. The tank was then filled with water to within about two feet from the top. This done, the manhole was closed and the wingknobs tightly fastened. Ten carboys of sulphuric acid, averaging 161 pounds each, or a total of approximately 1,600 pounds each, or a total of approximately 1,600 pounds, were poured into the tank by means of a syphon inserted into the copper funnel. The syphon was made of lead, to resist attack by the acid. The acid was fed in according to a prescribed schedule and rate: five carboys at first, followed by a waiting period equal to the time expended in pouring the acid; then three more carboys, followed by a second time interval; and finally the remaining two carboys. The timed delays between pourings were adopted to prevent too rapid generation of gas, which might strain the walls of the tank. The generated gas then passed through the copper elbow coupling the forward end into the rubber hose which conveyed it into the water cooler, from which it again passed into the lime purifier which absorbed the impurities and foreign gases. As a result, the gas which flowed from the lime solution into the balloon envelopes was almost pure hydrogen.

    In filing the balloons, care had to be exercised to prevent impure gas from entering the envelopes. For this reason the connection between the balloon and the purifier was not made until a pure stream of hydrogen could be obtained. The gas passed from the generator tank at a high temperature, and the connecting pipes to the water cooler became so hot that the hand could hardly bear to touch them. But after passing through the cooler and purifier, the gas was barely warm when it entered the balloon.

    Barring accidents, and when handled by competent men, the whole process from the time of preparations to the completed inflation of one of the larger balloons was approximately three hours. Normal inflation of a balloon in the field, Lowe wrote to General Hooker's adjutant general in March, 1863, "never required over three hours and fifteen minutes, and since adding my last improvements ... the gas makes in two hours and thirty minutes."

    The construction of the generators for the corps was begun about the same time that Lowe commenced building the four balloons authorized in September, 1861. By October 21, Lowe reported to Colonel Macomb that the generators were under construction and would be ready for service with the completion of the balloons. They were built under Lowe's plans and supervision by naval carpenters at the Washington Navy Yard. The copper pipes, couplers, flanges, and other fixtures were supplied by Megee and Sons of Philadelphia. Goodyear's Rubber, Belting and Packing Company, of the same city, furnished the hose, rubber pipes, packing and other similar materials. A total of twelve of these portable gas works were built for the corps, six of which were in service in the field by the close of 1861. They were painted a pale blue, with bold black lettering bearing the legend, "Lowe's Balloon Gas Generator," and a serial number.


    The satisfactory mobility of the generators was proven successfully in several major campaigns. They accompanied the army through the sloughs and mudholes of the Peninsula's impossible roads; through the snow and mire of the Peninsula's impossible roads; through the snow and mire from Washington to the slaughter field at Fredericksburg in mid-winter; over the mountain roads of western Virginia after Antietam; and over the wagon tracks of the wilderness in the Chancellorsville campaign. Only once, during the critical action of the Seven Days when McClellan withdrew to the James, was it necessary to abandon any of this equipment to the enemy. In this instance, three generators were left on the field, comprising the only aeronautic equipment ever captured by the Confederate forces.