164 
from what I have since seen on the large vacant orbs of aquarium 
cod-fishes, &c. ae , 
I have not yet seen the porpoises in the Brighton Aquarium, 
but suspect that if they contrive to ‘make themselves at home” 
there, a careful study of their habits will remove some of the 
difficulty which Prof. Huxley experiences in believing in their 
intelligence. W, Matrigu WILLIAMS 
Instinct 
A DIFFICULTY occurred to me on reading Mr. Lewes’s inter- 
esting and instructive article on “ Instinct” in NATURE of 
April 1o—and as no satisfactory answer offers itself to me, I 
venture to trouble you with it. 
Wherein lies the difference in kind between the actions per- 
formed instinctively by animals for the preservation of them- 
selves or their young, and those actions performed by plants 
with the same result ? 
For instance; the Ivy Linaria grows on an old wall; its 
flowers and the flower-stalks stand out for the sun and insects to 
visit the little ‘‘snap-dragon.” Butno sooner does the corolla 
fall, than the peduncle begins to ¢urve inwards to the wall, and 
usually contrives to tuck its seed-vessel well into the brickwork 
again. Wecannot say of such an action that there is ‘no alter- 
native open to it;” and even if we do, it does not explain it 
to callit ‘‘impulsive,” and yet one is not prepared to accept 
it as an instance of instinct. I shall be grateful for any 
elucidation. M. 
Grus vipio 
I oBsERVE that in your report of the meeting of the Zoological 
Society on the 6th ult., in your issue of the 15th, it is stated, 
with reference to Gvws vipio (seu leucauchen), that ‘‘no example 
of this fine species, so far as was known, had previously been 
brought alive to Europe.”’ Last autumn, when going over the 
Zoological Gardens at Amsterdam with the superintendent, Mr. 
Hegt, I saw there a splendid pair of these birds, which had been 
purchased for 140/., and had bred the same spring, and reared 
successfully a fine young bird, about two-thirds grown when I 
saw it in September, destined, as I was informed by Mr. Hegt, 
for the Berlin Gardens. The collection of cranes at Amsterdam 
is exceedingly rich, far surpassing either London or Antwerp in 
this respect. It contained, when I sawit, fourteen out of the fifteen 
valid species of Grus, comprising, besides the above-mentioned, 
G. vifio, a splendid pair of G. viridirostris, a fine G. deucogeranus, 
G. carunculatus, G. canadensis, G. Americana, G. torquata, 
&c., the desideratum being G. monacha, of Japan. 
W. A. FORBES 
Culverlea, Winchester, June 2 
ON THE SYNTHESIS OF MARSH-GAS AND 
FORMIC ACID, AND ON THE ELECTRIC 
DECOMPOSITION OF CARBONIC OXIDE * 
7 connection with the investigation on the electric de- 
composition of carbonic-acid gas referred to in a 
previous communication to the Society, I was led to sub- 
mit a mixture of hydrogen and carbonic-oxide gas to the 
action of electricity in the induction-tube, the mixed gases 
being circulated through the tube by means of an appa- 
ratus which I will not now describe. A contraction was 
soon observed to have taken place, which at the end of an 
hour amounted to 10 cub, centims. The rate of contrac- 
tion steadily diminished, and during the fifth hour of the 
duration of the experiment amounted to only 2 cub. 
centims. The experiment was stopped, and the gas 
analyzed with the following results in two several 
analyses :— 
I. Il. 
Carbonic oxide 61°65 | Carbonic oxide 61°35 
Hydrogen . 32°16 Hydrogen. . . 32°34 
Marsh-gas. . . 6°14 Marsh-gas. . 6°31 
10°00 100°00 
A small quantity (about 2 per cent.) of nitrogen was 
* A paper read at the Royal ty by Sir B, C. Brodie, Bart., D.C.L., 
F.R.S., late Wayneflete Professor of Chemistry in the University of Oxford.. 
NATURE 
[Xame 26, 1873, 
also contained in the gas, together with a trace of oxygen, 
which have been omitted from the calculation, 
The result of this reaction is expressed in the following 
equation :— sh 
CO+3H,=CH,+H,0. . 
This fundamental experiment, which constitutes the 
basis of a new method of chemical synthesis, susceptible 
of the most varied applications, and of peculiar interest 
in reference to the explication of natural phenomena, was. 
commenced by me on the roth of January last at Oxford, 
in the laboratory of my friend and successor in the Chair 
of Chemistry, Prof. Odling; two analyses of the gas 
were completed, and the results attained in the course of 
a week from that date. In a similar experiment made 
with a mixture of hydrogen and carbonic-acid gas, a con- 
traction also occurred, attended with the formation of 
water. The gas which resulted from the experiment was 
found to consist (after the absorption of carbonic acid) of 
hydrogen and carbonic oxide, together with a little marsh- 
gas. Traces of oxygen and nitrogen were also present. 
Minute drops, too, of an oily liquid appeared in the tube. 
This liquid, after the conclusion of the experiment, was 
dissolved in a small quantity of water. The solution was 
strongly acid and had a pungent taste. It reduced an 
alkaline solution of terchloride of gold and an ammoniacal 
solution of nitrate of silver. These reactions are the 
characteristic properties of formic acid, of which we may 
infer the synthesis to have been effected according’ to the 
equation 
H,+CO,=H,CO,. 
I may avail myself of the present opportunity to place 
on record the following important facts in reference to the 
action of electricity on carbonic-oxide gas. 
When pure and dry carbonic oxide is circulated 
through the induction-tube, and there submitted to the 
action of electricity, a decomposition of the gas occurs, 
attended with a gradual and regular contraction, which, 
in the form assumed in my experiments, occurred at the 
regular rate of about 5 cub. centims. in an hour, Car- 
bonic acid is formed, and simultaneously with its forma- 
tion a solid deposit may be observed in the induction- . 
tube. This deposit appears as a transparent film of a 
red-brown colour, lining the walls of the tube. It is per- 
fectly soluble in water, which is strongly coloured by it. 
The solution has an intensely acid reaction. 
The solid deposit in the tube, in the dry condition be- 
fore it has been in contact with water, is an oxide of 
carbon. Samples, however, made in different experi- 
ments do not present precisely the same composition ; 
but nevertheless they appear to belong toa certain limited 
number of forms which repeatedly occur, and may invari- 
ably be referred to the same general order or system. 
This system is, or appears to be, what I may term a 
homologous series of ‘‘ oxycarbons,” of which the unit of 
carbon with the weight 12 may be regarded as the first 
term, and of which the adjacent terms differ by an incre- 
ment of carbonic oxide (CO) weighing 28, precisely as 
homologous series of hydrocarbons differ by the incre- 
ment CH, with the weight 14. I have succeeded in iden- 
tifying by analysis two at least of these substances, 
namely, the adjacent terms C,O. and C.O,. From this 
point of view these peculiar bodies are members of a 
series of oxycarbons analogous in the oxycarbon system to 
the series of hydrocarbons of which the unit of carbon is 
the first‘and the unit of acetylene C,H, is the second 
term, the oxycarbon C,O, being represented in that 
series by the hydrocarbon crotonylene C,H,, and the oxy- 
carbon C.O, by the hydrocarbon valerylene C.H,. 
THE LAW OF STORMS DEVELOPED* 
Ill. 
PROM the Cape of Good Hope, in a straight line to- 
ward the projecting eastern coasts of Brazil, mariners 
have found a peculiar streakj of south-easterly winds. 
* Continued from p, 148, 
