281 
THE COTTAGE GARDENER. 
[August 8. 
Many of our readers represent to us, that from their 
situation in towns and other causes, they are unable to 
have a sufficient supply from that only true mine of 
fertilizing matter—the Dung-hill; and to meet their 
wishes, we purpose giving a series of papers upon arti¬ 
ficial manures. We shall rarely touch upon proprietary 
manures, but confine ourselves for the most part to 
those which may be obtained of any dealer in such 
articles. Before commencing our observations, w'e would 
warn our readers that all artificial manures, unless 
rich in animal and vegetable substances — substances 
affording to the roots of plants carbon, hydrogen, and 
ammonia (the chief constituents of their whole frame, 
whether it be a fragile petal or a sturdy stem)—are but 
assistant manures. They may help a plant to vigorous 
growth, the same as a richer milk may supply more 
phosphate of lime to a rickety child, but unless there 
are in the soil the more essential supply of decomposing 
animal and vegetable remains, such as are supplied by 
dung-hill manures, failure in securing productive growth 
must ensue. An artificial manure, deficient either in 
such remains or their components, can do no more than 
supply a constituent to a plant which may promote its 
vigour, or it may render a soil less dry by absorbing 
moisture from the atmosphere, or it may make an adhe¬ 
sive soil more friable. It may kill weeds and vermin, 
and it may preserve plants from injury when exposed 
to drought or to frost, but these are only secondary 
benefits. The most important office of a manure, let us 
ever bear in mind, is to supply carbon, hydrogen, and 
ammonia to the roots of plants in such a form that they 
can feed upon them. 
Taking a dealer in manures’ list, and adopting his 
alphabetical arrangement, we come first to 
Alum ; but let no one of our readers look towards 
this with any sanguine anticipations that it will brace 
and invigorate his plants. We have no experience of 
its merits ourselves, nor do we anticipate that it will act 
direct upon any plant with beneficial effect, though it 
may be of use in the mode mentioned by M. Sprengel. 
We will quote his statement, and leave our readers to 
judge for themselves. “ I have found, in repeated ex¬ 
periments, that alum, composed of 11 parts potash, 10 
parts alumina, 34 sulphuric acid, and 45 water, is a very 
powerful manure. It does not, like gypsum, merely 
advance vegetation by the sulphuric acid it contains,* 
but also by its potash and alumina. Alum is very 
soluble in water, and must not be used, therefore, except 
in small quantities, unless the soil contains much car¬ 
bonate of lime, in which case gypsum will be formed. 
Forty or fifty pounds arc generally sufficient for a Mag¬ 
deburg acre (equal to half an acre English). Alum will 
chiefly improve crops belonging to the tribe of clovers, 
although it also benefits oats and barley. Further ex¬ 
periments will show whether it is advantageous to other 
crops; and if analogy be not deceiving, this will be the 
case. If much humic acid is in the soil, the alum will 
be decomposed, humate of ammonia formed, and the 
* M. Sprengel is not quite correct here. Gypsum is a constituent of 
clovers, saintfoin, &c.; and it fixes ammonia, forming sulphate of ammo¬ 
nia the same as is done by alum. 
sulphuric acid set free. On soils rich in humus (the 
soluble extract of decomposed vegetables), it is to be 
used with caution. Alum may bo used as a fixer ol 
ammonia in urine, sulphate of ammonia being formed 
by the mixture.” It is in this last mode mentioned by 
M. Sprengel that it is most likely to be beneficial; and 
Dr. Ingle, of La Hague, in the Island of Jersey, states> 
that if used for the purpose in a stable, it speedily re¬ 
moves the strong ammoniacal smell; a pailful of water, 
with half a pound of alum dissolved in it, being suffi¬ 
cient for the purpose. This must be sprinkled over the 
urine-moistened parts. 
Alum has been employed also, with some success, to 
change the colour of the hydrangeas flowers from pink 
to blue. About seven years since some experiments 
on this subject were tried in the Chiswick Garden, 
and the plants submitted to the trial were exhibited at 
the rooms in Regent-street. One plant cultivated as 
usual was the most healthy, and bore its pink flowers; 
another, to which half an ounce of phosphate of iron 
had been administered, was unhealthy, its leaves yellow, 
and its flowers small but pink; a third plant, treated 
with half an ounce of caustic potash, looked similarly; 
but a fourth hydrangea, to which half an ounce of alum 
had been given, produced blue flowers. The quantity, 
however, was excessive, for the plant was weakly and 
the flowers small. Mr. Beaton finds that the best mode 
of obtaining blue hydrangeas is, by rooting cuttings of 
them in February, and potting them in loam with which 
iron filings have been mixed. See page 243 of our 
second volume. _ 
Resuming the subject of the comparative value of hard 
and soft water for culinary purposes, we come next to 
the evidence of a practical chemist, Mr. Philip Holland, 
who, in confirmation of M. Soyer’s statements relative 
to their employment in tea-making, observed:— 
“ I find that the water softened by means of oxalate of 
ammonia extracts the strength of tea almost twice as well as 
when it is hard. I had tea made with equal quantities of the 
leaf and equal quantities of boiling water, with and without 
oxalate of ammonia. The infusion made with water softened 
by the oxalate was strongly and better flavoured, and had to 
be diluted with the addition of 80 per cent, of hot water to 
bring it down to the strength of the other. It follows, therefore, 
that with the oxalate 10 parts of tea go as far as 18 without it. 
“ Does that saving pay for the expense ?—Over and over 
again; my tea costs me about Is. a-week : if I can save 
eight parts out of 18, I can have as strong and better 
flavoured tea for less than 7d. a week, being a saving equal 
to half the water rate. It is not easy, however, to get these 
savings effected regularly, it is apt to be forgotten, and 
cannot well he left to the servants. It would be far- better 
to have a water originally soft, if it were procurable.” 
The reason why hard water is so inefficient for 
making an infusion of tea is easily understood when wo 
consider its composition; 100 parts of green and black 
composed as follows: 
Tannin. 
Black. 
... 40 0 .... 
... 0 3 .... 
Green. 
. 34 0 
. 59 
Albumen. 
... G-4 .... 
. 57 
Lignin (woody fibre) 
... 44-8 .... 
. 51-3 
Volatile Oil., &c. 
... 1-9 .... 
. 25 
100.0 
1000 
