In this chapter we must discuss the phenomenon, which was discovered by us. The phenomen can have practical meaning for mineralogy, medicine ( speleotherapy ) and speleology in general. It is connected with the presence of hydrogen peroxide in the earth's crust.

In the cracks of the earth's crust the question of H₂O₂ existence hasn't been discussed up to the present [41], but it doesn't cause any doubt. We bring several ways of hydrogen peroxide origin below. In the cracks of the earth's crust, where proceeding only from the geothermal gradient, in average account with 1 km. depth the temperature of rocks grows in 30^O, the temperature reaches hundred degree their being real is quite acceptable from the point of view of chemical kinetics.

1. In the earth's crust the main source of hydrogen peroxide origin is the oxidation of methane and other carbo-hydrates containing in a natural gas. Methane forms the main part of the natural gas. H₂O₂ in considerable quantity appear at the time of its oxidation [42]. This phenomenon is researched in details and it is confirmed. For example, in 465 ^OC at the time of 80 % CH₄ oxidation up to 0,3 % H₂O₂ springs up. At the time of CH₄ oxidation the main elementary acts which generate H₂O₂ are:

HO₂ + CH₄ = H₂O₂ + CH₃
K = 1.10^-10.exp(-96/RT) [43]

HO₂ + CH₂O = HCO + H₂O₂
K = 1,9.10^-12.exp(-54/RT)

HO₂ + HO₂ = H₂O₂ + O₂
K = 4.10^-12

HO₂ + CH₃OH = H₂O₂ + CH₂OH
K = 1.10^-12.exp(-48/RT)

2. Oxidation of hydrogen containing in the bowels. Hydrogen oxidation is also researched in details and H₂O₂ springs up in considerable quantity is confirmed in experimental way in the process of H₂ oxidation. H₂O₂ springs up with the following elementary acts:

HO₂ + H₂ = H₂O₂ + H
K = 10^-11.exp(-24/RT)

HO₂ + HO₂ = H₂O₂ + O₂
K = 4.10^-12

HO₂ + H₂O = H₂O₂ + OH
K = 10^-13.exp(-30/RT)

In the bowels of the earth there are hydrogen and oxygen in considerable quantity, consequently H₂O₂ origin this way is also real.

3. The interaction of water and oxygen in the conditions of high pressure and temperatures of the bowels. For example in P = 1000 atmosphere and T = 1200 ^OC conditions the interaction of 1 mol water and 0,5 mol oxygen gives 2,1.10^-4 mol H₂O₂ [44].

[44a] refers to the existence of OH^-, O₂^-, N2⁺, H₃O⁺ in the cave are. They are formed the air components under the impact of a - particles, emitted by the radioactive radon, present in the cave air.

It should be noted, that other sources of formation of such particles exist. Not discussing the details of this aspect, let's note, that the radiation impact on H₂O causes formation of higher number of particles, then that mentioned in [44a]. This following particles can be added to the list: H, O₂, O, OH, HO₂, HO₂^- etc., which are in equilibrium with molecular H₂O, O₂ and H₂O₂. Hydrogen peroxide easily decomposes heterogenously, and as a result both neutral radicals, such as OH and HO₂ and ion forms can be formed.

Our investigations have shown [56], that the reactions with participation of H₂O₂ or the fractions of its decomposition have considerable speed and place under very low hydrogen peroxide concentrations ( H₂O₂ : air = 10^-5 ), and thus presence of infaugible quantities of H₂O₂ or other simple particles mentioned above in the caves will be enough for the processes to be discussed below to take place.

• Besides mentioned ways there is also a number of others, such as, for example [44]:
• biological - chemical reactions proceeding under the influence of microorganisms,
• the decomposition of the organic substance percolating into the bowels of the earth with subsoil waters,
• H₂O₂ origin at the time of ozone thunderstorm and its transference to the bowels of the earth with rains and other.

We think that the given examples are enough to prove that there are always H₂O₂ considerable quantity in the cracks of the earth's crust.