SODA. 127 
The soda of commerce is obtained from sea-water ; 
and from the ashes of different kinds of plants that 
grow on the sea-shores, but particularly from that called 
salsola soda, which is found in great abundance on the 
coasts of the southern parts of Europe ; and from which 
it has its name. It is sometimes called barilla, from 
the salsola soda being so denominated in Spain. 
This alkali is of essential use in the arts. When 
melted with flint or sand, it forms glass, and answers 
much better for this purpose than potash. In conjunc- 
tion with oil and lime, it is employed in the manufacture 
of soap ; and it is used as a substitute for soap in the 
cleaning and bleaching of Jinen, flannels, and worsted 
goods. If a weak solution of soda be poured into foul 
bottles, or casks in which wine has long been kept, it 
will cleanse them. It may also be successfully used 
for the cleansing of vessels in which milk has become 
acid. Saddles, bridles, or boot-tops, may be effectually 
cleaned by means of this liquor, and restored nearly to 
their original colour and appearance. 
The art of soap-boiling may easily be illustrated by 
the following experiment. Take a piece of quick-lime, 
slake it gradually by sprinkling on it a sufficient quan- 
tity of water. When it is completely slaked, add to it 
about twenty times its weight of water. To this mix- 
ture add two parts, by weight, of common subcarbonat 
of soda, previously dissolved in a sufficient quantity of 
water. Boil the whole for about half an hour, strain, 
it through a cloth, and boil it till so much of the water 
is evaporated that a phial that will contain an ounce of 
water will hold one ounce, seven pennyweights and a 
half, of this ley. Then mix in an earthenware pipkin 
or basin, one part of the ley, with two parts of olive 
oil. Place the mixture in a gentle heat, capable only 
of making the liquor simmer, and allow it to simmer, 
stirring the liquor continually, with a wooden stick, till, 
by letting a few drops of it fall on a plate, the soap will 
be found to coagulate, and the water become speedily 
separated from it. After which, pour out the contents 
