E 71 ] 
tlie fertilizing principle, and may suggest many 6- 
ther ways of applying that cheap material to the 
purposes of agriculture. It is presumable that in 
this very slow combustion the sulphuric acid is ab¬ 
sorbed by the ashes, or rather earth, while the in- 
flamable matter is dissipated ; and that the union of 
the alkali and the acid forms a salt not unlike in its 
chymical relation to gypsum, or perhaps one that 
is more soluble, more impregnated with the acid— 
perhaps diluted vitriolic acid directly applied, wodlcl 
be found equally useful, or rendered more valuable 
by being combined with wood ashes, when native 
gypsum could not be conveniently had. If I right¬ 
ly recollect, Duhamel mentions that sulphuric acid 
scattered over weeds with a view to destroy them, 
made them grow with , additional vigor,.—At 
Amsterdam I found a number of vessels waiting 
for the ashes of the turf, the principal fuel of that 
place, and which is: supposed to contain sulphur.— 
This is purchased at,a high price and is carried 
into Brabant and ' Flanders as a manure, and must 
come extremely high to the cultivator because of 
the time that vessels are in waiting before they can 
receive a load, as it is sent them every day as slow¬ 
ly collected from the inhabitants—a very judi¬ 
cious regulation prevailing here which I could wish 
to see extended to all our large cities. It is found 
with us that want of proper repositories for ashes 
frequently occasions dangerous accidents. In Am¬ 
sterdam the city 'is divided into many rounds, a 
ieart goes every morning to each house and receives 
