REVIEW OF LIEBIG. 
5? 
fibrin, and casein, all three rich in sulphur, he in¬ 
quires :— 
“ From what source does the animal body derive 
these three fundamental components ? Unques¬ 
tionably they are obtained from the plants upon 
which the animals subsist; but in what form and 
in what condition, are they contained in plants? 
“ Recent investigations of chemists have enabled 
us to answer these questions with positive certain¬ 
ty. Plants contain, either deposited in their roots 
or seeds, or dissolved in their juices, variable quan¬ 
tities of compounds containing sulphur. In these 
nitrogen is an invariable constituent. Two of the 
compounds containing sulphur exist in the seeds 
of cereal plants, and in those of leguminous ve¬ 
getables, such as peas, lentils, and beans. A third 
is always present in the juices of all plants; and 
it is found in the greatest abundance in the juices 
of those which we use for the purposes of the table. 
“A very exact inquiry into the properties and 
composition of these substances has produced a 
very remarkable result, namely, that the sulphur- 
tiompound dissolved in the juice of plants, is, in re¬ 
ality, identical with the albumen contained in 
the serum of blood, and in the white of an egg; 
that the sulphur-compound in the seeds of the 
cereals possesses the same properties and compo¬ 
sition as the fibrin of blood: and that the nu¬ 
tritious constituent of peas, beans, and lentils, is 
actually of the same nature and composition as 
the casein of milk. Hence it follows that plants, 
and not animals, generate the constituents of blood 
containing sulphur. When these are absent from 
the food given to an animal, its blood can not be 
formed. From this it also follows, that vegetable 
food will be proportionally nutritious and fit to 
sustain the vital processes of the animal body, ac¬ 
cording to the amount of these ingredients con¬ 
tained within it. 
“ There also exists certain families of plants, 
such as the cruciferse, which contain peculiar sul¬ 
phur-compounds much richer in that element than 
the vegetable constituents of blood. The seeds 
of black-mustard, the horse-radish, garlic, onions, 
and scurvy-grass, are particulariy marked in this 
respect. From all of these plants we obtain, by 
simple distillation with water, certain volatile oils, 
differing from all other organic compounds not 
containing sulphur, by their peculiar, pungent, and 
disagreeable odor. 
“ These compounds containing sulphur are pres¬ 
ent in the seeds of all plants, as well as in the 
plants themselves; and as they are particularly 
abundant in cultivated plants employed for animal 
nutrition, it is quite obvious that a substance con¬ 
taining sulphur is absolutely essential to the de¬ 
velopment of such compounds, in order to supply 
to them their proper proportion of this element.” 
These are very remarkable statements, and re¬ 
quire to be considered with great attention. The 
opinion, however, that sulphur is beneficial to 
plants is not originally Liebig’s; he, on the con¬ 
trary, so lately as 1842, adopted the erroneous 
views of Christison and Turner, and regarded the 
“hydrosulphate of ammonia (sulphuret of am¬ 
monium) as a deadly poison to vegetables, the 
properties of which we can not change by dilution.” 
(Ed. 2, p. 195.) It was, however, proved exper¬ 
imentally by Mr. Edward Solly, (First Report of 
the Chemical Committee of the Horticultural So¬ 
ciety, p. 9, June, 1842,) that this was a mistake. 
“ I made use of the hydrosulphuret of ammonia, 
the very compound described by Liebig as being 
a ‘ deadly poison ;’ but in place of killing plants, I 
found that in small quantity it produced decidedly 
beneficial effects: in some cases when it was ap¬ 
plied to plants in an unhealthy state from the ac¬ 
tion of other substances, it had the effect of in¬ 
vigorating them, and of restoring their leaves to a 
healthy, green, and crisp condition. The plants 
with which these effects were best observed were 
the garden-lettuce and the common Windsor-bean. 
The solution of the hydrosulphuret of ammonia 
employed was prepared by mixing a saturated so¬ 
lution of the compound with fifty times its bulk of 
water: such a solution had a most nauseous dis¬ 
gusting smell, and contained of course a large 
quantity of sulphuretted hydrogen. The plants 
under experiment were selected from many, and 
were of the same age and size, and as far as pos¬ 
sible in the same healthy state of growth. Some 
were watered with common water, others with a 
dilute solution of hydrosulphuret of ammonia. 
At first only a few drops of the solution were giv¬ 
en, but finding that this produced little or no effect, 
the dose was increased, and as much as half an 
ounce a day, and sometimes even more, was given 
to each plant; it was found that those thus treated 
became stronger and sturdier, their leaves were 
of a bright deep-green, the space between the nodes, 
or the distance from leaf to leaf, was shorter, and 
the stems were stronger, and the whole plant more 
flourishing than in those watered in the ordinary 
way, although all other circumstances were alike, 
and care was taken to place all under the same 
condition, by exposing them equally to air and 
light, and giving them the same quantity of water 
every day. Plants in a languid state from over¬ 
doses of nitrate of potash, or soda, or other saline 
manures, if not too much injured by their previous 
treatment, appeared to recover more rapidly when 
watered with the solution of hydrosulphuret of 
ammonia, than when merely treated with com¬ 
mon water. In some of these latter cases a much 
stronger solution was employed than that already 
mentioned, containing two drachms of the saturated 
solution of hydrosulphuret of ammonia in fifty of 
water, and of this eight drachms were given daily. 
For sometime after thus watering the plants, the 
earth retained a strong smell of sulphuretted hy¬ 
drogen, and the water which drained through, 
when tested by a salt of lead, evidently contained 
a large quantity of that gas.” And then he pro¬ 
ceeds to point out the extreme improbability, that 
a substance so constantly evolved from decaying 
matter as sulphuretted hydrogen should not be the 
food of plants. “ Its presence in manures is well- 
known and readily proved, but its presence in the 
air, in which it exists in exceedingly minute quan¬ 
tity, is less readily shown. We know, however, 
that it is constantly being formed on the surface 
of the earth, and we have evidence of its presence 
in the air by several effects, such as the tarnishing 
of some metals, and the blackening of white paint 
