,
Teylers Museum In 1772,
Joseph Priestley Marsilio Landriani was studying pneumatic chemistry with
Pietro Moscati when they attempted to quantify Priestley's nitric acid test for air quality. Landriani used a pneumatic trough in the form of a tall, graduated cylinder over water. As it measured the salubrity of air, he called it a eudiometer An associate of Moscati's,
Felice Fontana also designed a eudiometer on the same principles and quantified the salubrity of the air. The eudiometer with the nitrous air test was the way
Jan Ingenhousz verified that the bubbles given off under water by plant leaves exposed to sunlight were oxygen bubbles. His description of
photosynthesis was published in 1779, and in 1785 he wrote about eudiometers in
Journal de Physique (v 26, p 339). According to a biographer, Ingenhousz indicated that "many instruments were called eudiometers although strictly speaking they didn't deserve the name ... misunderstandings could exist when not everybody was using the same instruments." an Italian physicist who is well known for his contributions to the
electric battery and
electricity. Aside from its laboratory function, the eudiometer is also known for its part in the "
Volta pistol". Volta invented this instrument in 1777 for the purpose of testing the "goodness" of air, analyzing the
flammability of gases, or to demonstrate the chemical effects of electricity. Volta's Pistol had a long glass tube that was closed at the top, like a eudiometer. Two electrodes were fed through the tube and produced a spark gap inside the tube. Volta's initial use of this instrument concerned the study of swamp
gases in particular. Volta's pistol was filled with
oxygen and another gas. The
homogeneous mixture was taped shut with a cork. A spark could be introduced into the gas chamber by electrodes, and possibly
catalyze a reaction by
static electricity, using Volta's
electrophorus. If the gases were
flammable, they would explode, and increase the
pressure within the gas chamber. This pressure would be too great and eventually cause the cork to become airborne. Volta's pistol was made with either glass or brass, however due to the electricity the glass was vulnerable to exploding. Volta's extensive studies on measuring and creating high levels of electric currents caused the electrical unit, the
volt, to be named after him. In 1785
Henry Cavendish used a eudiometer to determine the fraction of oxygen in the Earth's atmosphere. == Etymology ==