June 21, 1873.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS 
1015 
important, taking for a type the alcoholic solution of 
young and fresh nettle leaves. 
The leaves, wetted with dilute alcohol, are to be bruised 
rapidly in a mortar, then expressed with the fingers and 
filtered. The green tincture which results gives the four 
bands, distributed from red to green, of fresh chlorophyll. 
The “specific” band appears at from 20° to 24°.* A 
drop of hydrochloric acid being added, the black band of 
the red is transported laterally to about 15° ; at the same 
time the limit of the red is extended in the same propor¬ 
tion. The liquor becomes yellowish and slightly turbid. 
This band, much widened, is in reality composed of two 
distinct rays, which may be separated either by diluting 
the liquor slightly with alcohol, or, more surely, by dimi¬ 
nishing the thickness of the solution. One of these bands 
appears then in the ordinary place, 20° to 22° ; this is the 
“ specific” band. The second, “accidental” (itself double 
sometimes), appears at about 15°, preceded and followed 
by a very decided red tint.f In the remainder of the 
spectrum the colours are slightly obscured, and it is only 
after an interval of time, varying from half an hour to a 
day, that the “ supernumerary ” bands of the altered 
chlorophyll become visible, at the same time as the “ acci¬ 
dental ” ray of the extreme red is gradually extinguished 
in the darkness which limits the spectrum on that side. 
The addition of the alcohol should be carefully made, for 
it miy happen that a too great dilution of the solution, 
instead of separating the “accidental” band, prevents its 
appearance; this it would do by overshooting the ephemeral 
state of the solution to which the band owes its origin. J 
The generation of this “accidental” band presents 
numerous variations; thus it may be that the “ specific 
band in the red undergoes no modifications either in posi¬ 
tion or in extent, but the limit of the red is extended, 
and from it there arises a very thin, dark band, followed 
quickly by a second, and these finish by combining into a 
single thick, dark band, which acquires the same breadth 
and tint as the former, and soon afterwards disappears in 
the obscure extremity of the spectrum. 
As an important detail, the author adds, that if the 
leaves, after being once expressed, are again treated with 
alcohol, a new tincture is obtained, possessing a. smaller 
degree of sensitiveness than the first. The sensitiveness 
of the solution also diminishes after it has been prepared 
a few days. Solutions from old, but unaltered leav es, 
accord less readily than those from young leaves with the 
phenomena above indicated, which appear to belong to a 
particular state of the chlorophyll at the period of forma¬ 
tion, when the stability of its elements is less complete. 
If the solution be filtered just as the two bands in the 
red are clearly seen, there is, with the clear liquid, a dis¬ 
appearance of the “accidental” ray—only the “ specific 
band and the “ supernumerary ” bands of the most re¬ 
frangible portion of the spectrum being produced. If the 
solution be allowed to clear by standing, there is the same 
disappearance of the “accidental” band, which can be 
made to reappear momentarily by agitation. 
The colouring matter which accompanies the chloro¬ 
phyll in certain plants,—red beetroots for example,—may 
sometimes mask the “ supernumerary ” bands of the chlo¬ 
rophyll, but the “specific” band of the red always 
appears, as well as the “ accidental ’ band, under the con¬ 
ditions before mentioned. 
The foregoing results are also obtained (and that natu_ 
rally because of the acidity of the plant) with the leave g 
of the sorrel; but what is most curious is that the “ acci¬ 
dental” band, after attaining the same intensity as the 
“ specific,” becomes increasingly stronger, whilst the latter 
becomes more feeble, until sometimes at the end of an 
hour it has completely disappeared, and there remains but 
one band of absorption, two or three degrees in width, 
having its centre at about 15°. In order to observe all 
the details of this phenomenon, it is often necessary, from 
the feeble coloration of the solution, to use it in a thick¬ 
ness of from eight to ten centimetres. 
Many other plants, especially the red cabbage and the 
St. John’s wort, present peculiar “ accidental ” or per¬ 
manent bands, and to these the author proposes to cal- 
the attention of the Academy on a future occasion. 
THE DIRECT SYNTHESIS OF AMMONIA A 
BY W. F. DONKIN. 
The action of induced electricity on mixtures of certain 
gases has been lately shown by Sir Benjamin Brodief to 
yield very interesting results. 
An obvious application of his method was to treat a 
mixture of dry hydrogen and nitrogen in a similar manner 
as those referred to above, with the view of effecting the 
synthesis of ammonia ; and Sir B. Brodie kindly allowed 
me the use of his apparatus for the purpose of the experi¬ 
ment, which was conducted as follows :— 
A mixture of about three volumes of hydrogen with one 
of nitrogen in a bell-jar over water, was passed through 
two tubes containing pumice moistened with alkaline 
pyrogallate and sulphuric acid respectively, then through 
a Siemens induction-tube, and into a bulb containing 
dilute hydrochloric acid. The whole apparatus being first 
filled with pure hydrogen, about half a litre of the mixed 
gases was sent through the apparatus, the induction-coil 
not being in action; the bulb containing the acid was then 
removed and another substituted, containing an equal 
volume of the same acid. 
About half a litre of the mixed gases was now passed 
through the apparatus, submitting them to the action of 
the electricity. The contents of the two bulbs were next 
transferred to two test-tubes ; and after adding excess of 
potash to each, Nessler’s test was applied. The first solu¬ 
tion gave a faint yellow coloration, the second a rather 
thick reddish-brown precipitate. 
No attempt was made to estimate the quantity of am¬ 
monia formed, as it would vary with many of the condi¬ 
tions of the experiment. 
Since writing the account of the above experiment, 
which was made in Dr. Odling’s laboratory at Oxford on 
March 24, I have seen in the ‘Comptes Rendus’ for April 
22, 1873, a note of an experiment by Messrs. Th&iard of 
Paris, in which they observe the formation of traces of 
ammonia by the action of electricity on a mixture of hy¬ 
drogen and nitrogen ; but no details of the mode of oper¬ 
ating are given. 
* = to 1-2 Sorby. . ... 
f This is a verbatim translation, the words m the original 
memoir being, “ precedee et suivie d une teinte tres 
tranche.” But perhaps, “ preceded and followed by a 
narrow W6ll-m£trlk6(l red bciiid. would loottcr moot tlio 
facts of the case.—E d. Ph. J. 
x The appearance of the “accidental is due to the 
unlocking of the chlorophyll compounds by the reagent, 
which acts upon one very rapidly and less rapidly upon 
another, all being differently soluble in different menstrua, 
such as carbon bisulphide, alcohol, ether, etc.—E d. Ph. J. 
LABORATORY NOTE ON THE RED AND GREEN 
IODIDES OF MERCURY.t 
by f. b. williams. 
Nearly ten years ago I was frequently engaged in the 
manufacture of considerable quantities of red and green 
iodides of mercury. At first I was in the habit of washing 
the green iodide with alcohol to purify it from adhering 
red Iodide, as is usually done. But on one occasion, >y 
reason of a misunderstanding, the proportion of iodine was 
considerably increased, and therefore the union between it 
* Read before the Royal Society, May 1, 1873 (Proceed- 
m f S Proceedings of Royal Society, April 3, 1873, and 
Pharm. Journ., 3rd series, vol, in. pp. 130, loO. 
x From the Chicago Pharmacist tor May. lb/<5. 
