September 6,1883 J 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
203 
bers of the Brassica family it is largely present. As members of 
this family are largely grown in gardens, much more so than in 
the fields, and as common stable manure as well as most other 
manures contain sulphuric acid in but trifling quantities, some 
0’1 per cent, (at most 3*5 in the ash of), there is reason for 
believing that the use of sulphates in the garden would be 
beneficial. 
In the form of gypsum (plaster of Paris) and salt-cake, or 
sodic sulphate, it is to be had cheaply, and also as sulphate of 
magnesia and Epsom salts; but when sulphate of ammonia is 
used to supply nitrogen, or superphosphate to furnish phosphoric 
acid, or gas lime to furnish lime, there will be no need to go into 
the market for gypsum. On a plot of Cauliflowers and Cabbages, 
as against an equal quantity of ordinary lime, gas lime, with us, 
gave much better results even when ordinary manure was 
liberally supplied. On poor ground to Savoys, Brussels Sprouts, 
and Swedes its effect was even more marked still, and one could 
tell at a considerable distance that something extra had been 
applied across one end of the plot containing our winter Brassicas. 
In ordinary lime sulphur is present, but generally in quantities 
too small to be worth noticing. In gas lime the sulphite, sul¬ 
phide, oxysulpkide, and hyposulphide are present to the extent 
of from 20 to 30 per cent, in addition to from 4 to 5 of sulphur. 
These all in time become sulphate, but only after some months’ 
exposure. Applied at cropping time, gas lime kills; applied in 
October or November to land not to be cropped till spring, it 
feeds. It should always be applied very sparingly—not over 
half a ton an acre. 
Sulphur exists in soil chiefly as calcic sulphate, and occasion¬ 
ally as magnesic sulphate. As calcic sulphate is not retained by 
soils, but is washed out by rains, heavy dressings are a mistake, 
and soils are generally deficient in sulphur. Even in calcareous 
soils little more than traces are to be found, and seldom as much 
as 0*5 per cent. 
Not unfrequently the floras of irrigated meadows will be 
found largely composed of plants which are favourably influenced 
by sulphates. This is owing to the presence of calcic, sodic, and 
magnesic sulphates in the water. The w r ater of the Trent con¬ 
tains not less than 21 grains per gallon of calcic sulphate, the 
Dunne Canal nearly 4, the South Esk 1, the Severn Loch 
Katrine 064, St. Mary’s Loch 081, Ben Rhydding nearly 3, the 
Critchmere (Surrey) 1‘07, and the Punchbowl (Surrey) 0.5 l J0. 
At London Bridge at high tide 44 grains per gallon have been 
detected. When such waters are used for irrigation purposes in 
the field or in the garden, more sulphur is supplied than is 
needed. In what are known as mineral waters sulphur is much 
more largely present, but we have given examples of what is 
common everywhere. For instance, 1‘Jl grains of sulphuric acid 
are in every gallon of the saline water of Purdon, N. Wilts. 
This is an extreme case, but most spring w r aters contain a good 
deal. From the clay slate 2 to 4, and the Muschel chalk 1 to 2 
per cent, is present. Calcic sulphate is present in the waters of 
Bath, Buxton, and Bristol, and also sodic sulphate to a lesser 
extent. In a pound of Kilburn water 18 grains of sodic sul¬ 
phate and 13 of calcic are present; 7 per cent, of magnesic 
sulphate is present is the chalybeate waters of Melrose. Sulphates 
are present in sea water. Strangely enough there are only 
traces in the intensely saline waters of the Dead Sea. 
IRON. 
In the majority of garden plants iron does not exist in 
large quantities. Ferric oxide is seldom present in their ashes 
in larger amounts than 1 or 2 per cent. An exception is found 
in Cabbage leaves; when in the ash it exists to the extent of 
8 per cent., but possibly not always. It is generally present in 
greatest quantities in fruits. In the ash of Strawberries 11T2 
per cent, of the phosphate has been found, and in that of the 
Orleans Plum 7*45. In Spinach 8*37 per cent., in Onion stalks 
10*61, and in Kidney Beans 5*24 is present, at least sometimes, 
but these are quite exceptional cases. 
Iron is regarded as an essential element of plant food. It 
is always found in them, and when absent in the soil the re¬ 
sulting plants are sickly. Under such conditions very weak 
solutions of copperas (ferric sulphate) have produced good effects 
according to Professor Johnson. We have heard of Roses being 
benefited by applications of Ron salts, but no scientific ex¬ 
periments that we know of have been conducted to prove its 
value when artificially applied. Iron salts turn Hydrangeas 
blue, and white Hyacinths red. 
Iron is present in sufficient quantities in ordinary manure, 
and is being continually added to the soil by the waste of tools. 
Naturally it exists in plenty in very nearly all soils, with the 
exception of pure quartz sands, which are sterile at any rate. 
In not a few it is too plentiful, and appears as red oxide in 
ordinary soils, and as black in black bands. In cultivated soils 
phosphate of iron is present. Wherever phosphates are applied, 
even in the ordinary form or as bones and stableyard manure, 
iron phosphates form sooner or later. The soluble phosphate 
in superphosphate speedily takes this form in soils where iron 
oxide abounds. This salt is very insoluble, but some plants 
ha/ve the power of appropriating it. Potatoes and the Legu- 
minosas do so. Turnips and the Brassica tribe generally do not. 
In addition to furnishing plants with food, ferric oxide has 
the property of “fixing” phosphoric acid, potash, ammonia, 
a property possessed by alumina, and humus. 
CHLORINE. 
Chlorine is found in all plants, but whether it is essential 
or not is disputed. It is used in the form of sodic and 
potassic chlorides. The first of these is always present in 
greater quantity than is wanted in ordinary manure, but as 
it is very soluble, and is not retained by soils, rains wash it 
out. It thus happens in inland situations that it is often 
deficient. Near the sea, however, chlorides are always present 
in the rain. At Cirencester it is calculated that the amount 
gained by the soil from the rain amounts to 53 lbs. per annum, 
at Rotliamstead 22, and at Penicuik near Edinburgh no less 
than 640 lbs. per acre. 
SODA. 
This is not regarded as essential by the more forward of 
modern agricultural chemists. As to its supply, what -we have 
said in regard to chlorine applies to soda, for in common salt the 
two are joined. Essential or not, common salt often has a 
beneficial effect on many crops. In inland situations on poor 
soils we have never seen it fail to tell on Cabbages, and for 
Asparagus its good effects are well known. It certainly furnishes 
food to plants, for although it is true that plants may be grown 
in soils containing no soda, though plants will not grow in soil 
containing no potash; yet, as a matter of fact, the very much 
cheaper soda will at least partially replace pota h. For instance, 
Salsola tragus, according to M. De Gasparin in the “ Cours 
d’Agriculture,” in the valley of the Rhone contains no soda, 
potash alone being present. The same plant between Frontignan 
and Aignes Mort ;s used as a source of soda. In ordinary soils the 
common Ice Plant, Mesembryantliemum crystalhnum, is covered 
with glands filled with oxalate of potash. In Teneriffe and near 
the sea in France this oxalate disappears, and sodic oxalate takes 
its place. 
With the exception of the Mangold, which contains quite a 
large amount of soda in its composition, and is decidedly bene¬ 
fited by applications of common salt, garden crops use much 
more soda than field crops. While cereal crops remove no more 
than from 3 to 5 lbs. per acre in the crops, Cabbages and others 
of the same order take up fully ten times as much. Salt is a 
very cheap manure, aud a few experiments will soon show 
whether a crop is the better for it. When its application is 
beneficial it will have the same effect as an extra amount of 
ordinary manure. Along with other salts common salt has the 
property of rendering otherwise insoluble matters soluble. 
Whether this is a benefit, as it is usually regarded, may be 
doubted. It may contribute to the loss from the soil of 
valuable phosphates. 
SILICA. 
This is held to be a non-essential by most scientists, although 
M. Georges Yille maintains the opposite, plants grown in calcined 
sand by him failing when supplied with it in a soluble form. 
Sachs grew Maize—decidedly a silica plant—without silica, yet 
it perfected its growth. Oats and Buckwheat have also been 
grown in perfect health without its aid, and Pierre has shown 
that the weakness in the straw, attributed to the want of silica, 
is due to other cause". 
Silica is mostly found in endogenous plants, such as the 
cereals and grasses. In them it is found on the outside of the 
plant, covering the straw or the husks of seeds. In these 
positions it certainly looks as if it were an excretion when 
we consider the peculiar anatomy of endogens. In the Equisetm 
it occurs in the same way as in the grains. In the “Pottery 
Tree ” of Para—actually used for making pottery—as much as 
77 per cent, occurs in the bark of old branches. It is absent 
from the grass which grows in peat bogs. In exogens it is 
chiefly found as a deposit inside the older cells of stems. They 
are present rather as incrustations than as part of the cells 
proper, and so may, even in such positions, be regarded as 
excretions. In trees it is most abundant in the bark and the 
older leaves. 
Silica is most probably taken up in the form of silicates of 
potash. Evidently the cereals and grasses are endowed with a 
special capacity of attacking these silicates. When they are 
