This section is from the book "Modern Buildings, Their Planning, Construction And Equipment Vol5", by G. A. T. Middleton. Also available from Amazon: Modern Buildings.
This class of limestone is very abundant in various parts of the country, more especially in the counties of Gloucester, Somerset, and Dorset; of the shelly variety in Northampton, Rutland, and Yorkshire; and of the coralline in Oxfordshire.
In general these stones are compacted of small rounded or granulated particles of calcareous material cemented together with carbonate of lime. Hence the term "Roestones" for the Bath and Gloucester varieties, in which these characteristics are prominent. In the Portland and Purbeck varieties shells of extinct organisms and fossil remains are freely interspersed throughout the mass. Some, such as Purbeck, have deposits that are capable of a fine polish, and are often classed under the head of marbles. Owing to the presence of clay in these stones the surface soon loses its polish, as the moisture of the atmosphere becomes absorbed in the material.
A slightly crystalline and finegrained stone, cemented with carbonate of lime; a free working and good weather stone. Can be had in large blocks. Colour, rich cream. Weight per cubic foot, 140 lbs.
A sound durable stone of very even grain, of great utility for carving and general ornamentation. Weight, 140 lbs. per cubic foot.
A fine-grained stone, sometimes slightly crystalline. A very useful building stone, working freely. Colour, a pleasing cream. Is composed of carbonate of lime, 96 per cent.; carbonate of magnesia, 2 per cent.; iron, 0.75 per cent.; alumina, 0.45 per cent. Weight, 145 lbs. per cubic foot. Crushing resistance, 228 tons per square foot.
Very similar to Ancaster, but is of a deeper colour. Care should be exercised in setting this stone on its proper quarry bed. Weight, about 134 lbs. per cubic foot.
A good workable stone of the shelly oolite variety, containing very small shells and fragments. Colour, brown. Weight, 134 lbs. per cubic foot.
A fine-grained stone, easily worked when fresh from the quarry. Hardens on exposure to the weather. Is a valuable stone for general building purposes. Colour, dark cream. Constituents - carbonate of lime, 92 per cent.; carbonate of magnesia, 4 per cent.; iron, 0.1 per cent. Weight, 128 lbs. per cubic foot.
Almost identical with the last named with respect to both quality, colour, and constituents, and from the same district.
A siliceous limestone of the same series as the Portland. There are three or four beds in the quarries having somewhat different characteristics. The lowest is extremely hard and of great weight, often as much as 154 lbs. per cubic foot. In colour a light brown.
The next bed above is more freely worked and not so heavy. In colour it is a greenish brown. Weight, 135 lbs. per cubic foot. The upper beds are more distinctly oolitic, and are of a cream colour. Weight, per cubic foot, 135 lbs. The constituents of the first two are about as follows - carbonate of lime, 80 per cent.; carbonate of magnesia, 4 per cent.; silica, 10 per cent.; iron and alumina, 2 per cent.
An easily worked stone of good building quality. To be had in good useful blocks. It is crystalline in structure, and of a light brown colour. Weight per cubic foot, 134 lbs. Constituents - carbonate of lime, 79 per cent.; carbonate of magnesia, 5 per cent.; silica, about 5 per cent.; iron and alumina, 8 per cent.
This stone is denser than the average of oolites, thus giving it a durability in smoky or damp atmospheres not to be attained by other stones of the same category. In general its colour is a whitish brown.
The best beds in the quarries, and the only ones now commercially worked, are those termed "Whitbed," producing a hard, firm, well compacted stone of great durability and strength. There is a considerable difference in the quality and density of the same class of stone taken from different quarries, but these are now almost entirely in the hands of two large firms of high reputation, who rarely quarry and never send out unsound stone. The weight varies in the different quarries and beds, averaging from 142 to 148 lbs. per cubic foot. Composition - carbonate of lime, 95 per cent.; carbonate of magnesia, 1 per cent.; silica, 1 per cent.; iron and alumina, small proportions.
There are several quarries of this stone, most of them possessing distinctive characteristics, both as to their weathering properties, working facilities, and their adaptability to different positions in buildings. Most are owned by the same great combination, whom it is best to trust, stating for what purposes the stone is required.
The centre of the industry is Box Hill, the principal quarries being as follows -
- An easily worked, compact, and even-grained stone of good weathering quality, which takes a good arris. Is a generally sound building stone. Colour, cream.
This stone has similar qualities to the Corsham Down, and is of fine grain and easily worked.
A very strong and even-grained stone, suitable for beds of columns, steps, engine beds, or positions where strength is required. It is not a good weathering stone, and is thus of more utility in internal situations. Presents considerable resistance to crushing. Colour, cream.
St. Aldhelm. - A sound even-grained building stone standing the weather well. Is not so fine as Corsham Down, but weathers better. In colour light brown.
There are several beds of this stone. It is even grained, capable of a good arris, and is suitable for inside work. Not of value in exposed situations. Colour, cream.
A sound even-grained stone, of use for general building purposes, and easy to work. Colour, light brown.
The general constituents of Bath stone are as follows, slightly varying in the various quarries: - carbonate of lime, 95 per cent.; carbonate of magnesia, 2.5 per cent.; iron and alumina, 1 per cent. Weight, from about 116 to 123 lbs. per cubic foot.
This stone is produced in two qualities, the soft and the hard. It appears to be a very good weathering stone, and is of even grain. In colour it is brown with black specks, probably of free carbon. Constituents - carbonate of lime cemented with lime and argillaceous matter. The soft stone weighs 142 and the hard 162 lbs. per cubic foot.