precautions.  The bottom of the pan remains suspended by means of the ropes.  The open spaces left all round between the bottom and the top of the furnace walls are then filled up, and the border of the pan, 9 inches to 10 inches high, is made of a similar mixture.  It is said that this extraordinary construction lasts from 40 to 50 days when well made, and that it can be filled 16 times in 24 hours, with an average of 500 litres of concentrated lye at each filling; but the quantity depends upon the weather, and is less in winter than in summer.  During the cold season one pan yields 140 litres (of salt) each time it is filled, and in the hot season from 190 to 210 litres.  The average consumpt of fuel is said to be 1500 kilos. in 24 hours.

In Persia, near Ballakhan, salt is still made, and has been made from time immemorial, in a very primitive way, which is described by Bellen, in his description of his journey in 1872 from the Indus to the Tigris, as follows:—­

“For several miles our road led over a succession of salt pits and ovens, and lying about we found several samples of the alimentary salt prepared here from the soil.  It was in fine white granules massed together in the form of the earthen vessel in which the salt had been evaporated.  The process of collecting the salt is very rough and simple.  A conical pit or basin, 7 or 8 feet deep and about 12 feet in diameter is dug, and around it are excavated a succession of smaller pits, each about 2 feet diameter by 11/2 feet deep.  On one side of the large pit is a deep excavation, to which the descent from the pit is by a sloping bank.  In this excavation is a domed oven with a couple of fireplaces.  At a little distance off are the piles of earth scraped from the surface and ready for treatment.  And, lastly, circling round each pit is a small water-cut led off from a larger stream running along the line of pits.

“Such is the machinery.  The process is simply this:—­A shovelful of earth is taken from the heap and washed in the basins (a shovelful to each) circling the pit.

“The liquor from these is, whilst yet turbid, run into the great central pit, by breaking away a channel for it with the fingers.  The channel is then closed with a dab of clay, and a fresh lot of earth washed, and the liquor run off as before; and so on till the pit is nearly full of brine.  This is allowed to stand till the liquor clears.  It is then ladled out into earthen jars, set on the fire and boiled to evaporation successively, till the jar is filled with a cake of granular salt.  The jars are then broken, and the mass of salt (which retains its shape) is ready for conveyance to market.

“Large quantities of this salt are used by the nomad population, and a good deal is taken to Kandahar.  The quantity turned out here must annually be very great.  The salt pits extend over at least ten miles of the country we traversed, and we certainly saw some thousands of pits.”