LUPTON : GOLD, SLATE, AND SALT MINES IN GREAT BRITAIN. 247 
to the tip. In this respect a slate-mine resembles more a Low Moor 
ironstone mine than a coal-mine. Many of the most extensive slate 
quarries are worked as open holes, fig. 5, consequently no pillars are 
required. An attempt is now being made to utilize some of the 
slate waste by crushing it to powder, and forming it into tiles and 
other kind of earthenware. 
Slate-quarrying is sometimes very profitable, and e)iormous 
fortunes have been made in this business ; but competition has cut 
down prices, so that the owners of the best quarries have to be con- 
tent with moderate gains, whilst the quarryman gains by increased 
employment, and the public by greater cheapness of a very useful 
article. When the competition of producers has at last reduced the 
price of any article to a minimum, it generally occurs to those 
engaged in the trade to endeavour to secure an increase of price by 
limiting the production ; an example of such an endeavour has been 
given to us in the salt trade. All the producers of salt in the country 
have combined to raise the price and limit the production, a line of 
conduct well within their legal and moral rights, but with their 
success in this combination we shall not rejoice, nor shall we sorrow 
with their failure. Nature, who has lavished on this island her 
choicest gifts, in a variety and abundance perhaps unparalleled else- 
where upon this earth, has endowed us with immense stores of rock 
salt, a mineral of the utmost value, and essential not only as an 
article of diet but to our immense chemical works. 
The old-established sources of production at Northwich and 
Droitwich have recently been supplemented by discoveries of salt on 
the banks of the Tees ; these discoveries have benefited the makers 
of alkali, but have tended to lower the price of salt. 
Salt at Northwich is found in a bed lying nearly horizontal, 
interstratified with red and blue marls of the Keuper series. It is 
reached at a depth of 50 yards, and the bottom of the salt is 110 
yards from the surface ; in the middle is ten yards of shale, fig. 6. 
The top ten yards used to be worked, leaving pillars ten yards high 
to support the roof, but these workings have been discontinued ; the 
old hollows are filled with water, which becomes brine by dissolving 
the salt ; this brine is pumped up and evaporated in great pans, two 
