SOILS, MANURES, &c. 239 
the fame treatment as the latter, except 
that it will not require more than twelve 
or fourteen months to prepare it for 
any purpofe. 
Manures are valuable in proportion to 
the falts and oils they contain, and are 
to be applied in quantity according to 
their quality. 
Hence it arifes that the dung of pigeons 
fhould be ufed in fmaller proportion than 
that of horfes, becaufe it contains more 
volatile falts ; and for the fame reafon, 
the afhes of burnt vegetables, containing 
A 
a conliderable proportion of fixed alka¬ 
line falts, muft be ufed more fparingly 
than pigeons dung, being ftill more pow¬ 
erful : for that which is very beneficial 
and highly proper in due proportion, or 
moderate quantity, becomes pernicious 
and dangerous in excefs ; therefore, all 
ftrong manures fhould be made ufe of 
with 
