wn 
¥90- 
To the Edzior of the Monthly abs Qzine. 
SIR, 
Tt will afford me pleafure to fee the 
following mifcellaneous obfervations, 
on the Operation of -Manures, circulated 
in your Publication: poffibly, fome of 
your chemical and experimental corre- 
{pondents may throw fome new light on 
the fubjeét; —a more ufeful difcuffion, 
you doubrlefs will admit, with me, can- 
not be brought betore the public. 
It is well known, that vegetable and 
animal manures will not contribute to 
the growth of plants, until they become 
putrid ; in which ftate they yield the 
phlogittic principle, and are more or lefs 
valuable and efficacious, in proportion 
tothe quantity of phlegifton they con- 
tain. 
Tt is for this reafon, that anzxal fub- 
farces, which poffefs the phlogiftic prin- 
ciple in greater abundance than vegeta- 
bles, are better manures. 
All alkaline and abforbent earths are 
enerally confidered as manures; but 
their action, in promoting the Soar of 
noae. is very different from putrid ve- 
getable and animal fubfiances. Every 
alkaline or abforbent earth attracts an 
acid in proportion to its ftrength. When 
thefe earths are perfeétly uncombined, 
they are cauftic; but when faturated 
with fixed air, they become quite mild. 
Fixed air is ftrongly attraéted by all ab- 
forbents, and is an acid, the qualities of 
which are totally different from ali 
others , when combined with abfoibents, 
it becomes neutral. 
Dr. PrrestvLey hath fhown, that ve- 
' getables contain a large proportion of ni- 
trous air, which isa maar fication of ni- 
trous acid: and he has alfo proved, that 
animal fubftances (the fa t excepted) con- 
tain nome of this nitrous air; but that 
in them a portion of fixed and inflamma- 
ble air is found. | 
vee e acid is a powerful antifep- 
tic, and muii be expelled before the fub- 
ftances that contain it, ean become pu- 
trid. The effet, therefore, of an add1- 
tion of alkaline fubftance, or abforbent 
earth, toa mafs of vegetable matter, 1s 
that of ugiting with this nitrous air, 
which counteraéts the putrefeent ten- 
dency of the yegetable fubftance ; and 
when. by this union, the acid is thus 
extrecied by thefe 
tion immediately takes place. 
Pulverifed limeftone, without any ris 
cination, is found to be a goed manur 
though lefs quick im its eperation than 
On the Operation of Manures. 
abforbents, putrefac- i 
f March, 
when calcined ; and is alfo, by its weight, 
in proportion "to its bulk, liable to ve 
loft {ooner, efpecialiy ailiete they prac- 
tife deep ploughing. 
There is great rifque in laying much 
lime on fallowed lands, where there is 
no vegetable fubftance for it to aét upon, 
ana acquire a certain degree of fatura- 
tion before the feed is fown ; yeta {mall 
quantity will quicken and promote the 
growth of the feed. 
Pulverization increafes fertility by in- 
creafing the furface to which nutritive 
principles i in the air may more eafily at- 
tach themfelves. 
The different. fpecies of manure con- 
tribute to the fertilizing of land, only in 
proportion as they introduce into it ‘a 
quantity of fpongy powder, oleaginous 
particles, or aeae falr. 
The quantity of nutriment which a 
plant derives from the earth, isin pro- 
portion to the number and magnitude of 
its leaves. The {maller and fewer thefe 
are, the lefs nourifhment is drawn. 
The nutrition of vegetables is like- 
wife moftly effected immediately by the 
leaves, which are the lungs of the plant. 
They not only ferve for raifing the fap, 
concoéting it, and difcharging its fu- 
perfluity, but are alfo a kindof roots, 
filled with delicately fine tubular veffels, 
that pump the juices from the air, and 
tranfmit them to thé neighbouring 
parts. 
It is a yulgar error, to fuppofe, that 
moffes impuver pp. land. At 1s true, that, 
loving cold and moiiture, it grows on 
poor wet lands; and becaufe fuch land, 
inthat ftate, ate little elfe, it has Ween 
fuppofed, that mofs renders it barren :— 
but the reverfe is true. The roots of 
mofs feldom penetrate more than half an 
inch in depth, and therefore can draw 
little from the foil. Take away the mofs, 
and inftead ef having more, there will 
be lefs grafs. The only way to improve 
fuch lands is .effe€tually to drain it, pre- 
vious to its being manured; grafs will 
then increate, and the mofs dvappear. 
Few, if any, mofiés are caten by cattle, 
For fuch lands as thefe, when broken 
py Patney barley is preferable to anv 
other: for it appears, by a paper in the 
Philofophical Tranfactions, for the year 
1678, that this fpecies of barley was re- 
commended to the Royal Society, as be. 
ing moft proper for cold countifies, on 
ccount ofits ripening within nine or 
ten weeks after it was fown. 
Cc 

R- 
achefier, Feb. q 197 
iMa ere 
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