PRODUCTION OF SALT AT THE CAPE DE VERD ISLANDS. 127 
ON THE EXTRACTION OF CHLORIDE OF SODIUM FROM THE 
SALT GROUNDS OF THE CAPE DE VERD ISLANDS. 
By J. Coleman Morgan. 
As is well known, the Cape de Verd Islands have a soil highly 
impregnated with salt. The amount of impregnation varies in 
the different islands, and it is worthy of remark that it is greatest 
in those whose surface in nearly flat. For instance, the mountain- 
ous region of St. Jngo, (whose principal town, Port Prayo, is 
the rendezvous of coast-bound vessels,) affords a quite pleasant 
and tolerably pure water, which is conveyed to a spot near the 
sea-side for the use of ships and the inhabitants ; while, in the flat 
country of the Isle of Sal, there is no fresh water whatever, and 
its 200 inhabitants are obliged to obtain supplies of brackish water 
by boats which ply daily to the Isle of Bona Vista, which is in 
sight and of some elelevation. The Isle of Sal, (the main salt 
ground) as are all the group, is peopled, to some extent, with 
Portuguese convicts, who, under the control of an overseer, work 
in the salt fields. These require description. They are each 
about one-half a mile square, and are surrounded by embankments, 
of which one, running through the whole, supports a railway used 
for the purpose of transportation. In each field, are a number of 
artificial springs or wells furnished with wooden pumps of very rough 
construction, standing 100 or 200 feet apart. These pumps have 
attached to their several piston rods, a crank, &c, connected with 
a kind of windmill, with sails of thin wood, of only about 12 feet 
diameter, but which, impelled by the great force of the N. E. trade- 
wind that is blowing constantly, raise many gallons of water in a 
short time. As this is discharged, it is conducted by troughs, dug 
to the depth of a few inches in the earth, into vats, which I 
found by measurement to be 17 feet long, by 6 wide, and 10 in. 
deep. These are allowed to fill, the supply is cut off, and the salt 
is allowed to crystallize by the evaporation of the fluid portion of 
the brine. The brine (whose strength, however, I did not deter- 
mine more closely) contains, 1 judged, about twenty per cent of 
the salt, and it may well be supposed, is intensely acrid to the 
taste 
