A SYSTEM OF 
38 
agents, the acid and the alcali, and that the caU 
t:areous earth might, under , certain circumftances, 
be changed into a mineral alcali, as fome have 
conjeftured; the neceffity of the exiflence of the 
calcareous earth is fulRcicntly obvious. But all 
thefe hyppthefes I pafs over, fince they for a long 
while have been, and will, perhaps, remain for 
ever undecided *, it being of more conlequence to 
take notice of the advantages which are to be de- 
rived from it in human oeconomy, fince it is more 
or lefs employed in moft trades. However, I do 
not intend to enter into all thofe particulars, but 
only to mention how the calcareous earth, when 
in its crude ftate, is commonly made ufe of. 
When in the form of a loofe earth, (Se6l. 
V. I.) it is ufed for white-wafhing •, and is 
mixed with clay in agriculture : for, according to 
Dr, KullbelFs rules of vegetation, its alcaline 
quality ferves to unite fat fubftances with water : 
befides that it is of a drying nature, and renders 
the clay lefs coherent, or, as the farmers fay, 
‘V makes the plowing eafier.” Hence this 
loofe earth, in fome foreign countries, is called 
marie •, for, when added to clay, it promotes the 
produ6lion of marie. The humus conchacea^ or 
fnell or fea-fand, is looked upon as pretty nearly 
of tlip fame quality, but it is unfortunate that 
clay for the mod part is fcarce in thofe places, 
where the calcareous earth is found in plenty, 
and that fometimes more is expefled from this 
lail than it poiTibly can perform. Loofe earth 
may eafily be made into lime, if it is previoufiy 
flacked with water, and made up in moulds. 
The indurated calcareous earth or dones, in 
maifes or lumps, are very ufeful in arable land, 
laecaufe it moulders by degrees on the furface, 
|ihd attra<ding the water, retains it longer than 
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