476 C.S. Garnett—Alteration of Shales in Derbyshire. 
ozone in dilute aqueous solution seem to be probably the only 
agents capable of such vigorous action—at least, under the natural 
conditions here prevailing. 
Wad contains a quantity of manganese dioxide, and, as is well 
known, the action of sulphuric acid on this results in the liberation 
of oxygen containing ozone. 
Some of the extremely numerous mineral veins in the limestone 
of the Winster district are famous in Derbyshire for the wad which 
they contain. Other minerals which are abundant in some of the 
local veins sre pyrites and marcasite, and the readiness with which 
these are oxidized, with the formation of sulphuric acid as one of 
the products, is well known. Large quantities of forms of the 
hydrated ferric oxides also occur in the veins, and much of this 
is probably of such origin. 
Manganese dioxide is not usually regarded as being suitably 
constituted for the production of hydrogen peroxide, but if it is 
formed in small quantity, as well as ozonated oxygen by the reaction 
between the acid and wad, and is carried forward in dilute solution, 
its action on the organic matter might be expected to be similar to, 
though less powerful than, that of ozone. 
Although ozone is well known to be a most powerful oxidizing 
substance which attacks and rapidly destroys organic matter, some 
normal shale was tested with ozone in the laboratory. The shale 
was crushed and suspended in water, through which oxygen contain- 
_ ing ozone was passed in the cold. The ozone readily attacked the 
organic matter of the shale, with the production of carbon dioxide, 
and the ready and complete disappearance of all ozone. ‘‘ Control ” 
experiments were conducted in order that any possible mistaken 
results would be excluded. 
Ozone (or improbably hydrogen peroxide) can be shown (by means 
of a mixed solution of starch and potassium iodide) to be readily 
formed by the action of extremely dilute sulphuric acid upon wad ; 
the ozone (and oxygen) entirely passing into solution. Thus, 
sulphuric acid derived as suggested, on coming in contact with 
wad, might be expected to give rise to the production of ozone, the 
solubility of which, in water, is considerable. 
On the south of the occurrence of altered shale, which is near 
the margin of the onset of the shale upon the limestone, the latter 
rises to 500 feet above the occurrence within half a mile of it. On 
this slope are almost innumerable small veins containing any or all 
of the minerals described. The natural drainage level of this 
area is, of course, the stream mentioned, the former bed of which 
abruptly marks the horizontal limit of the alteration in this direction. 
Vertically also, the level of the original bed seems to mark the limit 
in depth of the alteration, by a rapid but gradual transition. Just 
above the stream level, in the midst of.a completely altered horizon, 
and between bedding planes of the shale, the action of the slow | 
flowing of percolating water was very noticeable. 
