24 
MANURES 
different effects will be produced by different acids, 
Each base acts always one way, but each has an action 
similar to every other. Each acid acts also one way, 
but each has an action distinct from every other; im¬ 
press this on your mind. Reflect upon it a moment, 
and you will perceive that salts produce different 
effects, according to the nature of their acid. Now 
this may be illustrated thus: You take every day, 
probably with your every meal, common salt; that 
is, soda, a base, united to muriatic acid. Your di¬ 
gestion and health are all the better for it. You give 
your cattle a little salt. It does them good. Sup¬ 
pose now you change the acid of that salt, leaving 
soda, its base, in the same quantity you daily take. 
Instead of the muriatic, suppose you substitute the 
nitric acid, or, what is the same thing, suppose you 
use saltpetre from Peru, instead of common salt. You 
need not be told, that you would poison yourself and 
your cattle by so doing. You can drink, I dare say 
you have, cream of tartar punch. You feel the better 
for it. It is refreshing, cooling, opening. Now cream 
of tartar is a salt of potash; it is potash and tartaric 
acid. You have a fever. Your doctor gives you a 
sweat with Silvius’s salt; that is, acetate of ammonia, 
a salt composed of that and vinegar; or you take, 
perhaps, an effervescing draught, formed of lemon 
iuice and pearlashes. All does you good. But sup¬ 
pose now you change these cooling, vegetable acids 
for a mineral acid, say oil of vitriol. You may not 
take potash, united with a dose of oil of vitriol equiva¬ 
lent to the tartaric acid in the cream of tartar, with¬ 
out serious injury. So is it, reader, in farming, the 
acids of some salts are not only harmless, but benefi¬ 
cial to plants ; others are actual poisons. 
In the first case, salts help to nourish plants, as 
common salt helps to nourish yourself; in other 
cases, they poison plants, just as they would impair 
your constitution, perhaps kill you. But it is to be 
remembered, as in our own case, even those that 
