256 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. [September 21, 1870. 
substance this point is a specific one, each, vapour exhi¬ 
biting* rapid changes of volume and flickering movements 
when the temperature or pressure was changed, but 
showing no separation into two layers. Under these 
circumstances, it is impossible to say that the body exists 
either in the state of a gas or of a liquid; it appears to 
be in a condition intermediate between the two. Thus, 
carbonic acid, under the pressure of 108 atmospheres, 
and at 35*5° C., is reduced to the l-430th of the volume 
which it occupies at one atmosphere, it has undergone a 
regular and unbroken contraction, and it is a uniform 
fluid: if we now reduce the temperature below 31° C. 
the liquid condition is assumed without any sudden 
change of volume or any abrupt evolution of heat. We 
can scarcely too highly estimate the value of the re¬ 
searches of Andrews. 
As examples of the power which modern methods of 
research give of grappling with questions which only a 
few years ago were thought to be insoluble, I may quote 
the beautiful observations, now well known, by which 
Lockyer determined the rate of motion on the sun’s sur¬ 
face, together with those of Frankland and Lockyer 
respecting the probable pressure acting in the different 
layers of the solar atmosphere ; and lastly, the results 
obtained by Zollner, respecting solar physics, and espe¬ 
cially the probable absolute temperature of the sun’s 
atmosphere, as well as that of the internal molten mass. 
These last results are so interesting and remarkable as 
being arrived at by the combination of recent spectro¬ 
scopic observation with high mathematical analysis, that 
I may perhaps be permitted shortly to state them. 
Starting from the fact of the eruptive nature of a certain 
class of solar protuberances, Zollner thinks that the ex¬ 
traordinary rapidity with which these red flames shoot 
forth proves that the hydrogen of which they are mainly 
composed must have burst out from under great pres¬ 
sure : and if so, the hydrogen must have been confined 
by a zone or layer of liquid from which it breaks loose. 
Assuming the existence of such a layer of incandescent 
liquid, then applying to the problem the principles and 
methods of the mechanical theory of gases, and placing 
in his formulae the data of pressure and rate of motion 
as observed by Lockyer on the sun’s surface, Zollner 
arrives at the conclusion that the difference of pressure 
needed to produce an explosion capable of projecting a 
prominence to the height of 3*0 minutes above the sun’s 
surface, a height not imfrequently noticed, is 4,070,000 
atmospheres. This enormous pressure is attained at a 
depth of 139 geographical miles under the sun’s surface, 
or at that of l-658th part of the sun’s semi-diameter. 
In order to produce this gigantic pressure, the difference 
in temperature between the enclosed hydrogen and that 
existing in the solar atmosphere amounts to 74,910° C. 
In a similar way Zollner calculates the approximate ab¬ 
solute temperature of the sun’s atmosphere, which he 
finds to be 27,700° C., a temperature about eight times 
as high as that given by Bunsen for the oxyhydrogen 
flame, and one at which iron must exist in a permanently 
gaseous form. 
Passing on to more purely chemical subjects, we find 
this year signalized by the redetermination of a most 
important series of chemical constants, viz. that of the 
heat of chemical combination, by Julius Thomsen, of 
Copenhagen. This conscientious experimentalist asserts 
that the. measurements of the heat evolved by neutral¬ 
izing acids and bases hitherto considered most correct, 
viz. those made with a mercury calorimeter by Favre 
and Silbermann, differ from the truth by 12 per cent., 
whilst the determination by these experimenters of the 
heat of solution of salts is frequently 50 per cent, wrong. 
As the result of his numerous experiments, Thomsen 
concludes that when a molecule of acid is neutralized by 
caustic alkali the heat evolved increases nearly propor¬ 
tionally to the quantity of alkali added until this reaches 
B B 3 > or 5 of a molecule of alkali, according as the acid 
is mono-, di-, tri-, or tetra- basic. Exceptions to the 
law are exhibited by silicic, and also partly by boracic, 
orthophosphoric and arsenic acids. In the two latter the 
heat of combination is proportional for the two first 
atoms of replaceable hydrogen, but much less for the 
third atom. A second unexpected conclusion which 
Thomsen draws from his calorific determinations is that 
sulphuretted hydrogen is a monobasic acid, and that its 
rational formula is therefore H S H. 
Another important addition made to chemistry since 
our last meeting is a new, very powerful and very sim¬ 
ple form of galvanic battery, discovered, though not yet 
described, by Bunsen. In this second Bunsen’s battery 
only one liquid, a mixture of sulphuric and chromic 
acids, and, therefore, no porous cells, are employed. 
The plates of zinc and carbon can all be lowered at once 
into the liquid, and raised again at will. The electromo¬ 
tive force of Jhis battery is to that of Grove—the most 
powerful of known forms—as 25 to 18; it evolves no 
fumes in working, and can be used for a very consider¬ 
able length of tune without serious diminution of the 
strength of the current, so that Bunsen writes me that 
no one who has once used the new battery will ever 
think of again employing the old forms. I had hoped 
to be able to exhibit to the section this important im¬ 
provement in our means of producing a strong current, 
but war has demanded the use of other batteries, and 
Bunsen has been unable to send me a set of his new 
cells. 
Amongst the marked points of interest and progress 
in inorganic chemistry during the past year, we have to 
notice the preparation of a missing link amongst the 
oxysulphur acids by Schutzenberger. It is the lowest 
known, and may be called hydrosulphurous acid, H 2 S 0 2 . 
The sodium salt, NaHS0 2 , is obtained by the action of 
zinc on the bisulphite; as might be expected, it possesses 
very powerful reducing properties, and bleaches indigo 
rapidly. The metallic vanadates have also been care¬ 
fully examined, and the existence of three distinct series 
of salts proved, corresponding to the phosphates, viz., the 
ortho- or tribasic vanadates, the pyro- ortetrabasic vana¬ 
dates, and the meta- or monobasic vanadates. Of these 
the ortho-salts are most stable at a high temperature, 
whilst, at the ordinary atmospheric temperature, the 
meta-salts are most stable. In the phosphorus series, 
as is well known, the order of stability is the reverse; 
and thus the points of analogy and of difference be¬ 
tween phosphorus and vanadium become gradually ap¬ 
parent. 
As an illustration of the results of modem organic 
research—for in viewing the year’s progress in this 
ever-widening branch of chemistry it is impossible to do 
more than give a few illustrations—I may quote Baeyer’s 
remarkable investigations on mellitic acid. Originally 
discovered by Klaproth in honeystone or mellite (a sub¬ 
stance which yet remains the only source of the acid), 
mellitic was supposed to be a four-carbon acid. Baeyer 
has quite recently shown that the acid contains twelve 
atoms of carbon, or has a molecular weight three times 
as great as was originally supposed. He has shown that 
mellitic acid is benzolhexacarbonic acid, C 12 H 6 0 12 , or 
benzol in which the six atoms of hydrogen are replaced 
by the monad radical, carboxyl (COOH); as benzoic is 
benzol-mono-carbonic acid, or benzol in which one of 
hydrogen is replaced by carboxyl. The most interesting 
portion of Baeyer’s research, however, lies in the inter¬ 
mediate acids, partly new and partly acids already pre¬ 
pared, which he has shown lie between mellitic and 
benzoic acid, and in which from one to six atoms of hy¬ 
drogen in benzol are respectively replaced by carboxyl. 
Nor is this all, for he has proved that, with two excep¬ 
tions, each of these six acids is capable of existing in 
three isomeric modifications, thus giving us an insight 
into the arrangement of the molecule of these aromatic 
compounds. For the simplest mode of explaining these 
numerous isomers is that given by Baeyer in the different 
order in which the several atoms of hydrogen in the 
