PROFESSOR THADDEUS LOWE
THE CIVIL WAR YEARS
Invention of the 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)
National Air and Space Museum of the Smithsonian Institute Donated by Lance S. Ferm - 2011
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.