This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
Hydrogen, being the lightest of known elements, is commonly taken as a standard of specific gravity and combining proportion. It has been found free in small proportions in certain volcanic gases, and occurs extensively in combination, e.g., in water, in many acids and gases, in hydrocarbons, and all substances used for artificial light - tallow, oils, coal-gas, etc.- and throughout the vegetable kingdom. It was formerly known as "inflammable air," and when lighted burns with a bluish flame.
By acting on granulated zinc with dilute sulphuric or hydrochloric acid - Zn + H1SO4=ZnS04 + H1
A colorless, inodorous gas, of sp. gr. 0.0692.
This is negative in character. Hydrogen does not support respiration or combustion, and Priestley ascertained that animals immersed in it died as soon as in carbonic acid. Beddoes found that attempts to inhale it caused cyanosis of lips and face, quickness and smallness of pulse, vertigo, impaired vision, and in some persons, drowsiness, slight insensibility, and when pushed, asphyxia in greater or less degree. A mixture with oxygen, when inhaled, causes the voice to become shrill.
Dr. Beddoes used hydrogen gas as an inhalation in phthisis, both by itself and in mixture with oxygen. He reported some cases as relieved and others cured, but his results have not been corroborated. The most constant effect seems to have been the production of sleep.