276 INDEX. 
Salt, how manufactured, 131 
, bay, 132 
, spirit of, how made, and uses of, 132 
Saltpetre. See Nitre. 
Sand, common, description and uses of, 52 
Sandstone, 234 
Sapphire, Oriental, description of, how cut and set, SO 
, properties, value, arid use of, 30, 31 
~, false, or water, 49 
Sardonyx, 57 
Scots pebbles, description and use of, 62 
Scythe-stones, how made, 234 
Sea froth. See Meerschaum. 
Sea water, description and properties of, 244 
, cause of its bitterness, and saltness, 244 
' . , uses of, 245 
Serpentine, description and uses of, 89, 90 
Shell silver, how prepared, 181 
Shot, how made, 205 
Sienite, description and uses of, 230 
Silex, 15 
Siliceous earth, 15 
Silicium, 15 
Silver, description of, 177 
*- mines of Potosi and Norway, account of, 177, 178 
, found in Scotland, 178 
, extracted from lead, 178 
- , how extracted from its ores, 178 
-- , value and uses of, and how alloyed, 179 
-, marks or stamps on silver plate explained, 179 
plate, how cleaned, 179 
, ductility of, 179 
wire, 179 
, nitrat of, uses of, 181 
i . , fulminating, extraordinary properties of, 182 
, experiments with preparations of, 182 
, how to gild, 172 
Silvering of looking-glasses, process of, 176 
. of metals, how performed, 186 
. of paper and wood, 181 
Slate. See Roofing slate, and Writing slate. 
Slate pencils, how made, 78 
Slickenside, extraordinary properties of, 218 
Smalt, of what formed, and uses, 221 
, strewing, 221 
Smaragdus, 38 
Snowdon diamonds, what they are., 47 
Soap, how made, 127 
