326 
dice may prevail, without the existence 
of wilful design to counteract the hypo- 
thesis of another ; but, surely, one must 
be guilty of a degree of voluntary and 
infatuated blindness, or of absolute 
ignorance, when, in spite of surround- 
ing circumstances, the same system is 
inveterately retained. 
Descartes, if so great a name needs to 
be adduced in support of an obvious 
maxim, recommends that “ we should 
not decide upon the most trivial truths, 
without close and accurate previous 
analysis.” And this ought to be the in- 
variable rule of all who have attained 
to, or aim at, respectable rank, in the 
extensive schools of philosophy: it 
would remove many of the prejudices 
that are now thoughtlessly imbibed. 
Another cure for what we may call 
mild: prejudices, will result from mingled 
conversation and social intercourse. It 
is too often the case (and here I speak 
of my own country in particular) for 
men of real and undoubted scientific 
and literary attainments to glue them- 
selves (so to speak) to their books, or 
to their writing-tables, despising conver- 
sation with ordinary men. Need it be 
added, that this is an extremely per- 
nicious practice, and favours the growth 
of wrong notions, whichit is afterwards 
extremely difficult to eradicate: for, in 
fact, from the plainest understanding 
something may be culled, which may 
add utility, if not ornament, to the stu- 
dent’s—to the master’s store. So many 
instances of the truth and importance 
of this observation rush upon the mind, 
that, perhaps, Ishall not add a very va- 
luable illustration, when the recollec- 
tion of your readers is directed to the 
lecture of a gentleman, highly celebrat- 
ed for his chemical knowledge, in which 
there was an actual failure in demon- 
strating the process of welding iron, 
from ignorance that a /luwa was neces- 
sary to the process: information which 
any ordinary blacksmith could have 
afforded him. 
To those who suffer themselves to be 
thus prejudiced, and who resist convic- 
tion, knowingly, and wilfully—who are 
guilty of akind of misprision of error— 
we scarcely know what to say. It is 
always in their power to do right; but 
if they find the path of truth un- 
pleasant—I believe we must even let 
them “ gang their ain gait,” until they 
find themselves deserted and alone in 
the midst of a crowd. Meantime, we 
mark’ with much satisfaction the rapid 
decrease of the dominion of prejudice. 
4 
Uses of Salt in Manufactures and Agriculture. 
[Nov. 1, 
In politics, trade, philosophy, literature, 
—in every branch of art and science,— 
in all the paths of useful, or of elegant 
inquiry—how evident and how consol- 
ing the gradual enfranchisement from 
the fetters of ancient prejudice! Even 
Quakers begin to talk, and dress, and 
‘live like other human beings. 
THERMES. 
— 
For the Monthly Magazine. 
Uses of Saut in Manuracturss and 
AGRICULTURE. 
MPORTANT advantages are now 
derivable from salt, since it can be 
procured without duty. In a work 
published by Dr. Rensselaer, some of. 
the purposes to which salt may be ap- 
plied are thus detailed. 
Sal ammoniac, or muriate of ammo- 
nia, is made in abundance from com- 
mon salt: the manufacture of this ar- 
ticle was abandoned, in England, in con- 
sequence of theheavy duty of £30 per ton 
laid on salt. In consequence, however, 
of bittern from the salt-works being 
allowed in Scotland for the manufac- 
ture, the price has been reduced nearly 
one-half. 
In the manufacture of glass, salt is 
largely employed; soda, which is pro- 
duced from common soap, is used for 
plate-glass ; potass, for flint-glass; and 
common salt, with kelp, for crown- 
glass. 
Oxymuriate of lime, and other oxy- 
muriatic salts, employed in bleaching, 
are made from salt; and large quantities 
of it are consumed in the manufacture. 
Spirit of salt, or muriatic acid, re- 
quires large quantities of salt —at least 
1000 tons were used for this purpose 
in England every year, notwithstanding 
the enormous duty. It is used in a 
variety of processes in dyeing and calico 
printing. 
Glauber’s salt is made from what 
remains after the distillation of mu- 
riatic acid. This residuum was for- 
merly thrown away, until a person em- 
ployed it in making Glauber’s salt, when 
a duty of £30 per ton was laid on the 
article manufactured—since, however, 
remitted. 
Epsom salts are produced entirely | 
from common salt, or the evaporation 
of sea-water; the brine, which yields 
100 tons of salt, gives from four to 
five tons of this valuable article. Dr. 
Henry, the celebrated chemist of Man- 
chester, has discovered a process of pre- 
paring it from magnesian limestone, and 
has reduced the price one-half. It ioe 
e 
