308 
COMPOSITION OF THE UPPER PERMIAN LIMESTONE 
IN SOUTH YORKSHIRE. 
J. W. H. JOHNSON, B.Sc. 
CONSEQUENT upon a discussion at the meeting of the Yorkshire 
Naturalists’ Union at Askern, in July, 1906, respecting the 
composition of the Upper (bedded or laminated) Permian 
Limestone in the south of Yorkshire, the writer analysed some 
specimens kindly obtained for him by Mr. Geo. Grace, B.Sc., 
with the following results :— 
Tickhill, Dearne Valley Dearne Valley 
Kkra Ora Quarry, towards Stainton Railway, Railway, 
Tickhill * (Extreme top Loversal Road _Loversal Road 
(Bottom Bed). bed). (Topbed). (Half way down). 
Organic and volatile nil 0.67 2.80 nil 
matter. 
Siliceous matter. 2.89 4.94 I .32 0.94 
Oxides of [ron and 
Aluminium, 2.25 2s 2X0) 1.29 0.94 
(Fe,03A1,03). 
Calcium Oxide 29.85 29.68 30.29 30.36 
(CaO). 
Magnesium Oxide 19.60 18.10 19.94 20.90 
(MgO.). 
Carbon dioxide 45-35 43.80 43.80 46.84 
(GOP): ——— SSS === ——— 
99 .94 99 -49 99 «44 99-95 
Molecular ratio, MgCO; 1.00 I .00 I .00 1.00 
CAc@Or. 1.088 eau eal .986 1.036 
The quantities of calcium and magnesium oxides given 
above represent only the amounts present as carbonates, care 
having been taken to avoid as far as possible any decomposition 
of the silicates of these bases. 
The specimens were of firm texture, with the exception of 
the one from the top bed in the Dearne Valley Railway cutting, 
which was somewhat friable, and also much. yellower in colour 
than the others. 
For the purpose of comparison, the analysis of the 
Lower (massive) Permian Limestone, as selected from Bolsover 
in Derbyshire for the Houses of Parliament, may be stated. 
It had the following percentage composition :— 
Moisture, 3-3; Silica, 3-6; Oxides of Iron and Aluminium, 
1-8; Calcium Oxide, 28-6; Magnesium Oxide, 19-1; Carbon- 
M2CO™ a 3.00 
CaCO, 1.067 
The composition of the Permian Limestone varies very 
considerably in different localities, ranging from that of a 
normal dolomite containing equal molecular proportions of 
magnesium and calcium carbonates to that of a limestone 
containing but a few per cent. of magnesium carbonate. The 
molecular ratio of these two substances present in the above 
samples shows that the limestone in this area’is dolomitic and 
resembles closely that of a normal dolomite. 
dioxide 43:6; Molecular ratio, 
Naturalist, 
