PART II
THE STUDY OF FOUR TYPICAL ELEMENTS HYDROGEN-OXYGEN-NITROGEN-CARBON AND THEIR MORE IMPORTANT COMPOUNDS CHAPTER I HYDROGEN
Symbol, H. Atomic weight = 1.008. Molecular weight =2.016. Density = i. 008. History. The existence of hydrogen as an individual sub- stance was first established by Cavendish (1766), who applied to it the name inflammable air. He obtained the gas by acting upon certain metals, as iron, tin, and zinc, with either sulphuric or hydrochloric acid. Occurrence. In the free state hydrogen occurs only in small quantities upon the earth. It is evolved with other volcanic gases, and is present in the gases which escape from petroleum wells. It is evolved also during the fermentation and decomposition of certain organic compounds, and is therefore present in the breath and the intestinal gases of animals. From these sources it finds its way into the atmosphere, where it is present to the extent of about .04 volumes in 1000 volumes of air. Hydrogen Has also been found in many specimens of meteoric iron, and also in certain rocks, where it is present as occluded gas. Hydrogen in the uncombined state exists in enormous masses upon the sun, and is present in certain stars and nebulae. The so-called prominences which are seen projecting from the sun's disk to a distance of many thousands of miles, and which were