538 
NATURE 
cr 
by one of the lights to be compared, the edge being turned to 
the observer. The great advantage here is that the two illu- 
minated parts are placed in sharp juxtaposition. 
On a Point in the Theory of Double Refraction, by R. T. 
Glazebrook.—The author suggested that the theory of double 
refraction given by Lord Rayleigh, in which the ether is sup- 
posed to have an effective density different in different directions, 
might be modified so as to agree with Fresnel’s theory, if it be 
not necessary to assume that the ether offers an infinite resistance 
to compression, but only that, as compared with its rigidity, its 
compressibility is very great, and further that in a crystal the 
light vibrations are normal to the ray, not to the wave normal, 
as was pointed out by Boussinesq and referred to by Ketteler in 
some of his papers. 
On a New and Simple Form of Calorimeter, by Prof. W. F. 
Barrett.—The bulb of a thermometer is made in the shape of a 
double cup. In this cup is placed the substance whose specific 
heat (say) is to be determined. The stem of the thermometer is 
horizontal, and rests on a fulcrum so that the weight of the sub- 
stance may be determined by using the apparatus as a balance. 
Special precautions are taken in determining the temperature of 
the substance when placed in the cup, and to prevent evapora- 
tion, &c. The specific heat is then given by the ordinary 
equation, 
WS(T - 0)= C(6 - 2), 
the constant C being determined by experiment once for all. 
SECTION B—CHEMISTRY 
On the Non-Existence of Gaseous Nitrogen Trioxide, by Prof. 
Ramsay.—After pointing out the inconclusive character of 
Lunge’s argument in support of the existence of gaseous nitrogen 
trioxide, inasmuch as the use of any reagent may either decom- 
pose the gas or react with the products of its dissociation—viz. 
NO and N,O,(NO,), as though they consisted of N,O, itself, 
the author shows the only criterion of the existence of this gas 
to be its vapour density. He finds that NO, may be mixed 
with NO without effecting any change in volume, and therefore 
no combination, or only a very slow combination, can take place 
between these gases. The vapour density of the first portion 
of the gas obtained by distilling liquid N,O 3 is found to be 
22°35, a result which accords fairly well with what the density 
should be, supposing it to be a mixture of N,O,, NO., and NO, 
having the empirical composition N,O,. Supposing the gas 
weighed to contain no N.O,, an assumption not warranted by 
facts, and consist of NO and NO,, then, in order to make the 
specific gravity 22°35, 17°63 per cent. of N,O, must be added 
to the mixture. These facts the author considers as deciding 
the point against the existence of gaseous nitrogen trioxide. 
Observations on some Actions of a Groves Gas Battery, by 
Prof. Ramsay.—The action of an ordinary Grove’s gas battery 
can be explained by supposing that, at the point of contact 
between the platinum, hydrogen, and liquid, a decomposition of 
the water molecule takes place, its oxygen uniting with the 
hydrogen gas to form water, whilst the hydrogen is liberated 
from molecule to molecule until the free gas arrives at the 
point of contact of the platinum, the oxygen, and liquid ; 
here it unites with the oxygen gas, forming water. If the liquid 
in the battery be coloured with indigo sulphuric acid, the author 
finds the indigo in contact with the hydrogen to undergo no 
changes, whereas that in contact with the oxygen is discoloured, 
a change probably due to the oxidation of the indigo to isatine. 
Hydrogen, therefore, in uniting with oxygen, does not bleach 
indigo. Now if, inzthe ordinary gas battery, the acid be re- 
placed by a saturated solution of sodium chloride and hydrogen, 
and chlorine be substituted for hydrogen and oxygen, the indigo 
is found to be bleached on both sides, the bleaching taking place 
from above downwards, and taking place at once on admitting 
the chlorine, but some time is required before the reduction 
by the hydrogen is evident. These experiments show that when 
hydrogen unites with chlorine it is in a more active state than 
when it unites with oxygen. To explain this difference the 
author suggests that, when a molecule of hydrogen unites with 
a molecule of chlorine, atomic hydrogen exists for a moment, 
and this, in presence of indigo, reduces it to indigo-white. In 
the case of hydrogen and oxygen the union of two molecules of 
the former with one molecule of the latter may be effected with- 
out the hydrogen assuming the atomic condition, whereas the 
oxygen must assume the atomic or nascent condition, to which 
the bleaching of the indigo may be ascribed ; or it may be that 
ozone or hydrogen peroxide are formed. These phenomena 
may, therefore, be regarded as chemical evidence corroborative 
of the following method of expressing the union of these gases 
with one another :— 
H,+Cl,=HCl+HCl 2H, +0,=H,0 + H,O. 
On the Spontaneous Polymerisation of Volatile Hydrocarbons 
at the Ordinary Atmospheric Temperatures, by Sir H. E, Roscoe, 
LL.D., F.R.S.—The attention of the author was drawn by Mr. 
Staveley, of West Bromwich, to a camphor-like solid, formed 
from the more volatile liquid hydrocarbons, produced by de- 
composing crude phenol at a red heat. The change from the 
liquid to the solid state was, at first, supposed to be due to the 
influence of the oxygen of the air, but investigation has shown 
the solid to be a hydrocarbon having the formula C,)H,9, and 
the change to be one of polymerisation. This solid hydro- 
carbon undergoes a further polymeric change when heated in a 
sealed tube at 180°. The author finds also that the first runnings 
of ordinary coal tar, which distil below 30°, are, on keeping in 
sealed tubes, converted spontaneously into this solid hydrocarbon 
Coe. 
On some New Vanadium Compounds, by J. T. Brierley.—The 
compounds described form a series of well-defined crystalline 
salts of purple or dark green colour, possessing a metallic lustre, 
which contain both the oxides V,O, and V,O;, and may be 
regarded as vanadate-vanadites. These salts are formed by 
adding a caustic alkali to the dark green liquid formed by 
adding hypovanadic sulphate to a solution of an alkaline meta- 
vanadate. The composition of the sodium, potassium, and 
ammonium salts are represented by the following formula :— 
2V,0,. V,O; . 2Na,0+13H.O ., 2V.0, . V,0;2K,0 +6H,0, 
and 4V,0,.2V,O; . (NH,),0+ 14H,0. 
The Essential Food of Plants, by T. Jamieson, F.C.S., 
F.I.C.—Whilst no doubt exists as to the essential character of 
the elements of carbon, hydrogen, oxygen, and nitrogen as con- 
stituents of the food of plants, the evidence in support of the 
elements phosphorus, potassium, magnesium, calcium, sulphur, 
iron, and chlorine to be regarded in this light cannot be con- 
sidered conclusive. A little consideration shows the two 
elements, iron and chlorine, have but little claim to be con- 
sidered as essential to the food of plants, and the experiments, 
of which an account was given in this paper, were made by the 
author with the view of vindicating the right of the five remain- 
ing elements to be so considered. These investigations were 
conducted at an experimental station in Sussex and also at one 
in Aberdeenshire, the nature of the soil in both cases being 
specially favourable. The method adopted consisted in observ- 
ing the effects on plants grown in similar soil and under similar 
conditions, when supplied with manures, containing all these 
elements and comparing the results with those obtained when 
one or other of these elements was withheld. These experiments 
seem to provide proof that sulphur must be discarded from the 
list of essentials, while some doubt is thrown on even lime and 
magnesia. At the same time striking confirmation is afforded 
of the essential characters of both phosphorus and potassium. 
A Plea for the Empiric Naming of Organic Compounds, by 
Prof. Odling, M.A., F.R.S.—Verbal translations of the struc- 
tural formulz assigned to organic compounds possess certain 
advantages as names for the several compounds. ‘Thus, they 
are applicable to all organic compounds of which the structural 
formulze are made out ; they are the only sort of names applic- 
able to complex isomeric compounds ; and their use cannot be 
dispensed with wholly in the case of even less complex com- 
pounds. Notwithstanding these advantages, structural names 
constitute unsuitable names for general use, more especially as 
applied to fundamental hydrocarbons, alcohols, and acids. They 
are objectionable for this use by reason of their length, com- 
plexity, and want of ready indicativeness ; by the circumstance 
of their being based on conceptions of chemical constitution of a 
kind pointed out by experience as eminently liable to change ; 
and by the further circumstance of their representing a one- 
sided and, so far, an untruthful notion of the bodies designated. 
Structural names, expressing other than a distorted view of the 
constitution of all but a few of the most simple of organic bodies, 
are impracticable by reason of their length and complexity. 
Hence, to avoid the distortion inseparable from the use of any 
single structural name for an organic body, the only expedient 
is the assignment to each body, in proportion to its complexity, 
of an indefinite number of structural names, a proceeding almost 
[ Oct. 1, 1885, 
