380 
combines with carbon, to form carbonic acid, 
and a metallic sulphuret remains. Five impor- 
tant sulphates are noticed in the articles Grr- 
sum, Epsom Sat, Guauper’s Saunt, Anum, and 
Coppmras; and both these and some others— 
particularly those of ammonia, potash, and bary- 
ta—perform important offices in animal and 
vegetable nutrition, in the fertilization of soils, 
in special manuring, and in medicine and the 
arts. See the articles Ammonta, Protein, Nv- 
TRITION, Foop or Puants, Manure, and Ageri- 
CULTURAL CHEMISTRY. 
Liebig—after showing that sulphur is a con- 
stituent of the protein compounds, and is as 
truly concerned as nitrogen in building up and 
maintaining the animal organisms, and becomes 
available to animals through the medium of the 
plants or parts of plants which they consume as 
food—says, “ Compounds containing sulphur are 
present in the seeds of all plants, as well as in 
the plants themselves; and as they are particu- 
larly abundant in cultivated plants employed for 
animal nutrition, it is quite obvious that a sub- 
stance containing sulphur is absolutely essen- 
tial to the development of such compounds, in 
order to supply to them their proper proportion 
of this element. It is also obvious, that although 
all other conditions for the nourishment of plants 
be present, if the compound containing sulphur 
be either wholly absent or deficient in quantity, 
the vegetable constituents containing sulphur 
will either be not at all formed, or they will be 
generated only in proportion to the quantity of 
the above compound. The air cannot contain 
any substances in which sulphur is present, un- 
less indeed we except minute and scarcely appre- 
ciable traces of sulphuretted hydrogen. The 
soil, therefore, must be the only means of fur- 
nishing the sulphur so necessary to the growth 
of plants; and we are ignorant of any form by 
which it can be assimilated except that in which 
| it enters the roots. The numerous analyses made 
of the water of mineral springs, furnish us with 
a satisfactory explanation of the form in which 
sulphur occurs in soils. The water of such 
springs is entirely derived from the rain which 
falls upon the surface of the earth; the water 
percolating through the earth, dissolves all solu- 
ble materials which it may meet in its course. 
The substances thus dissolved communicate to 
the water properties which are not possessed by 
pure water. Water procured from springs or 
wells is found to be very rarely deficient in solu- 
ble salts of sulphuric acid. The liquid obtained 
by lixiviating good soil from garden or arable 
land also contains very appreciable quantities 
of these salts. These facts leave little doubt as 
to the source whence plants obtain their sul- 
phur; as far as our knowledge extends, they 
receive it from the sulphates dissolved in the 
water absorbed by their roots from the soil. 
Ammoniacal salts, particularly sulphate of am- 
monia, are rarely detected in spring water; but. 
SULPHATES. 
this is owing to the constant presence of super- 
carbonate of lime, which effects their decompo- 
sition, and allows the escape of ammonia during 
the evaporation of the liquid for the purposes of 
analysis. According to our view, sulphate of 
ammonia is of all compounds containing sulphur 
the one most fitted for the assimilation of that 
element. Sulphate of ammonia contains two 
elements, both of which are equally necessary for 
the support of vegetable life; these are sulphur 
and nitrogen, and they form constituents also 
of vegetable albumen, fibrin, and casein. But 
what is still more worthy of observation, sul- 
phate of ammonia, viewing it according to the 
proportion of its elements, or what is termed its 
empirical formula (0°, H®, 8, N,), may be con- 
sidered as a compound of water with equal equi- 
valents of sulphur and nitrogen. Thus, by the 
simple removal of the elements of water from 
this compound, its sulphur and nitrogen might 
be enabled to pass over into the composition of 
the plants. The ingredients of plants contain- 
ing sulphur are so composed that one equivalent 
of sulphur exists for every 25 equivalents of ni- 
trogen. Hence it is obvious that much more 
ammonia must be offered to plants than that 
contained in the form of sulphate of ammonia, 
if all the sulphur of the latter is to become a 
constituent of the organic ingredients alluded 
to. This bears a complete analogy to the assim- 
ilation of the carbon and nitrogen furnished to 
plants in the form of carbonate of ammonia. 
This salt may contain two equivalents of carbon 
to one equivalent of nitrogen. Hence it is ne- 
cessary that the carbon of six equivalents of 
carbonic acid must at the same time be taken 
up, and enter into combination with the nitro- 
gen, in order to produce the principal nitrogen- 
ous constituents which contain one equivalent 
of nitrogen to eight equivalents of carbon. 
“The passage of sulphur derived from a sul- 
phate into the composition of vegetable matter, 
necessarily indicates that the sulphate has been 
exposed to the action of the same causes as those 
by which the decomposition of carbonic acid was 
effected in the plant; and, therefore, that the 
sulphuric acid has been decomposed into sul- 
phur and oxygen, the former of which is assimi- 
lated, whilst the latter is separated. If we sup- 
pose the sulphuric acid to be presented in the 
form of sulphate of potash or soda, the basis of 
these salts must be set at liberty after the de- 
composition of their acid. Now we actually find 
these bases in all cultivated and even in most 
wild plants. They are found either united to 
organic acids, or, what is still more remarkable, 
they are found in union with the vegetable com- 
pounds containing sulphur. The vegetable casein 
of pease, beans, and other leguminous plants, is 
itself insoluble in water; but it is very soluble in 
the form in which it occurs in the plant. This 
solubility is due to the soda and potash with 
which it is united. In like manner, the albumen 
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