=124. Gases evolved from radium.= Curie and Debierne[217] observed that radium preparations placed in a vacuum tube continually lowered the vacuum. The gas evolved was always accompanied by the emanation, but no new lines were observed in its spectrum. Giesel[218] has observed a similar evolution of gas from solutions of radium bromide. Giesel forwarded some active material to Runge and Bödlander, in order that they might test the gas spectroscopically. From 1 gram of a 5 per cent. radium preparation they obtained 3·5 c.c. of gas in 16 days. This gas was found, however, to be mainly hydrogen, with 12 per cent. of oxygen. In later experiments Ramsay and Soddy[219] found that 50 milligrams of radium bromide evolved gases at the rate of about 0·5 c.c. per day. This is a rate of evolution about twice that observed by Runge and Bödlander. On analysing the gases about 28·9 per cent. consisted of oxygen, and the rest hydrogen. The slight excess of hydrogen over that attained in the decomposition of water, they consider to be due to the action of oxygen on the grease of the stop-cocks. The radio-active emanation from radium has a strong oxidizing action and rapidly produces carbon dioxide, if carbonaceous matter is present. The production of gas is probably due to the action of the radiations in decomposing water. The amount of energy required to produce the rate of decomposition observed by Ramsay and Soddy—about 10 c.c. per day for 1 gram of radium bromide—corresponds to about 30 gram-calories per day. This amount of energy is about two per cent. of the total energy emitted in the form of heat.
Ramsay and Soddy (_loc. cit._) have also observed the presence of helium in the gases evolved by solution of radium bromide. This important result is considered in detail in section 267.
=125.= Walkhoff first observed that radium rays produce burns of much the same character as those caused by Röntgen rays. Experiments in this direction have been made by Giesel, Curie and Becquerel, and others, with very similar results. There is at first a painful irritation, then inflammation sets in, which lasts from 10 to 20 days. This effect is produced by all preparations of radium, and appears to be due mainly to the α and β rays.