LIME AND CEMENT. 289 
Quarry, the most famous in England, for Limestone ; it being 
very hard, and making excellent Lime, at Barrow in Leicester- 
shire."* 
Aberthaw, on the Glamorganshire coast, and Lyme Regis have 
been for long particularly favoured localities for hydraulic lime, as 
the material can be readily shipped in the raw state. At Aber- 
thaw the limestone was taken away in the form of large beach- 
pebbles, and burnt at the localities where the lime was wanted. 
Smeaton ascertained that the Lias lime made a harder mortar 
under water than any other lime with which he was acquainted. 
When he built the Eddystone Lighthouse he sent round the 
Land's End to Aberthaw for limestone, whereas, as De la Beche 
has remarked, he could have procured equally good material from 
Lyme Regis.f 
The character of the strata at the several localities has been 
already described, and it will be necessary here only to allude to 
the products. In some localities only lime is made, in others 
various kinds of hydraulic cement are also prepared. 
The lime obtained from the Lias is hydraulic in character : and it is stronger 
and also darker in colour (owing to the clay and iron), than the "fiit lime" 
obtained from purer limestones. Thus Lias lime is sometimes spoken of as 
" Brown lime," in distinction from the " White lime " or " Marble lime," 
made from the rich Carboniferous or Devonian limestones. Owing to its 
strong and binding character, the Lias lime is not, as a rule, adapted for 
agricultural purposes, though it is sometimes put on light lands, the " Marble 
lime " being used for heavy soils. 
There are, however, in some localities, layers of Blue lias that contain a very 
large percentage of carbonate of lime, and that when calcined, furnish a 
good agricultural lime. Good hydraulic limestone should have not less than 
15 percent, of clay. 
Lime is made from the limestone, which is burnt in masses as quarried, so 
that some of the coal-ash becomes commingled with it. 
The lime is supplied in the form of Lump lime and Ground lime. The 
Lump lime is used for mortar, being mixed (under a mill) with ashes, sand, 
pounded tile, brick-rubble, &c. It is also used for stucco, being mixed with 
clean sharp sand, in the proportion of i best lime and f sand. 
The Ground lime, which has already been ground in a mill, is used for con- 
crete foundations, and also for brick-work and stone-walling : it is especially 
valuable for reservoirs and water-works, for docks and sea-walls, tunnels, &c. 
For concrete 1 portion of lime to 6' or 8 of gravel is generally used. 
If ground so as to facilitate the slaking of every particle, and used imme- 
diately, the hydraulic limes produce a mortar which becomes much harder and 
far more durable than that of the rich limes. Blue Lias lime is now very 
often specified by Architects and Engineers for use in Mortar, as well as in 
Concrete j because the Mortar made from rich limes is not suited for damp 
situations, and when very dry it becomes friable. 
Lump lime is made sometimes from limestone containing a larger percentage 
of lime than that used for the Ground lime ; the latter is made from beds 
richer in alumina, and soluble silica. 
The Cement is prepared from the limestone and clay. The stone is broken, 
usually by a stone-crusher, and ground by millstones. The powder is then 
mixed with clay, the proportions being weighed. The materials are mixed 
with water in mixing-boxes or pug-mills. The wet masses are taken out in 
lumps, and sometimes roughly shaped into the form of bricks, and dried over 
a heated floor. The material is then put into the kiln ; and afterwards 
* Nat. Hist. Foss. England, vol. i. p. 26 
f Report on the Geology of Cornwall, etc., p. 507. 
E 70859. T 
