JUNE 15, 1899] 
NATURE 
167 
solute value of the freezing point, which can be worked out 
from the experimental researches of Regnault. The formula 
is based on the experimental proof by Joule and Kelvin, that 
the ratio between the cooling effect per atmosphere of differ- 
ential pressure and the pressure is constant for all pressures. 
Applying data from Regnault’s experiments to the formula de- 
duced by the author, the values of the freezing point are prac- 
tically the same as those given by Lord Kelvin. Hence it 
is thought probable that the discrepancies are due to inaccuracies 
in the experiments of Regnault which were conducted at con- 
stant pressure. The value of the zero calculated from experi- 
ments on hydrogen at constant volume made by M. Chappius 
is, if we treat hydrogen as a perfect gas, 273034. Applying 
a thermodynamic correction for the deviation of hydrogen from 
the laws of a perfect gas, the value of the freezing point be- 
comes 273719. This figure agrees very closely with the value 
27314 obtained by Lord Kelvin from the constant pressure 
experiments on air. The correction has only been applied to 
hydrogen, because in this case it is so small that a large per- 
centage error in its determination has a very small effect upon 
the absolute value of the freezing point. In constant pressure 
work the experiments are difficult to carry out, and the cor- 
rection is easily applied, while in constant volume work the 
experiments are easily performed, and the thermodynamic cor- 
rection is difficult to apply. Prof. Gray expressed his interest 
in the manner in which Mr. Rose-Innes had obtained his re- 
sults without using the experimental data of Joule and Kelvin, 
and pointed out that Lord Kelvin attached most importance to 
the results he had obtained for air. It would be useful to have 
the gas constants redetermined with greater accuracy. The 
compensating arrangement devised by Prof. Callendar would 
enable experiments at constant pressure to be carried out satis- 
factorily. Dr, Lehfeldt drew attention to the sign of the cor- 
rection applied by the author, and asked if it should not be 
negative instead of positive. He pointed out that variation in 
the specific heat of a gas might affect the formula, and said that 
Boltzmann had shown that it was impossible to determine an 
absolute temperature without introducing calorimetric measure- 
ments. As Joule and Kelvin had sometimes found positive and 
sometimes negative values for the cooling effect in the case of 
hydrogen, large percentage errors might occur in the value of 
the correction, Mr. Blakesley asked what the probable error 
was in the numbers given by Lord Kelvin. Mr. Watson said 
that the author had calculated the value of the freezing point 
from experiments on hydrogen, and had shown that the result 
agreed closely with the value of the zero deduced by Lord 
Kelvin from experiments on air. He would like to know what 
agreement would be got by applying Mr. Rose-Innes’ correc- 
tion to the case of air. Mr. Rose-Innes, in replying, said he 
agreed with Prof. Gray that it would be useful to have the 
constants redetermined. It was only in their early work that 
Joule and Kelvin observed a cooling effect for hydrogen, the 
bulk of the experiments giving a heating effect. The sign of 
the correction depended on the increase or decrease of the effect 
with temperature, and was positive in the case of hydrogen. 
Regnault has proved experimentally that the value of the specific 
heat is constant. 
Chemical Society, June 1.—Dr. W. H. Perkin, Vice- 
President, in the chair.—The following papers were read :— 
The hydrosulphides, sulphides and polysulphides of potassium 
and sodium, by W. P. Bloxam. The author has prepared 
substances of the following compositions :— 
K,S,2H,O; K,S,5H,O; K,S,12H,O; Na,S,9H,O ; 
2KHS,H,O ; NaHS,2H,O; NaHS,3H,O; K,S,,10H,0 ; 
K,S,,6H,O; K,S.,19H,O; K,S,,xH.O; K,S,),xH.O ; 
and Na,S9,14H,O. 
—On the relative efficiency of various forms of still-head for 
fractional distillation, by S. Young. The author has tested the 
efficiency of a number of forms of still-head in common use, 
and has devised new forms of greater efficiency.—The salts of 
dimethylpyrone and the quadrivalence of oxygen, by J. N. 
Collie and T. Tickle. The authors consider that dimethyl- 
pyrone chloride contains tetravalent oxygen, and has the 
following constitution :— 
peer Cee 
NCH:CMe” Ne 
—The symmetrical di-isopropylsuccinic acids, by W_ A. Bone 
and C. H. G, Sprankling. By the action of isopropyl bromide 
on ethyl sodioisopropylcyanosuccinate and subsequent hydro- 
NO. 1546, VOL. 60] 
lysis of the ethereal salt produced, the authors have obtained 
cts- and trans-di-isopropylsuccinic acid ; the dissociation con- 
stants have been determined.—Active and inactive phenyl- 
alkyloxyacetic acids, by A. McKenzie. Phenylalkyloxyacetic 
acids, in which the alkyl group is either ethyl, methyl, propyl 
or isopropyl, have been prepared from lzvo and _ inactive 
mandelic acid ; in some cases racemation occurs. —The chemical 
composition of the oleo-resin of Dacryodes hexandra, by A. 
More. The oleo-resin of Dacryodes hexandra contains levo- 
pinene, lzvosylvestrene, a resin and a white crystalline sub- 
stance which is probably ilicic alcohol.—The condensation of 
ethyl acetonedicarboxylate: the constitution of triethyl orcin- 
tricarboxylate, by D. S. Jerdan. The author has obtained a 
diethyl orcintricarboxylate as a new condensation product of 
ethyl acetonedicarboxylate ; the diethyl- and triethyl-salt both 
yield derivatives of two orcindicarboxylic acids, so that the con- 
stitution of triethyl orcintricarboxylate is determined.—A series 
of substituted nitrogen chlorides, by F. D. Chattaway and 
K. J. P. Orton. The authors have prepared a number of sub- 
stituted nitrogen chlorides by aid of a reaction represented by 
the following equation :— 
R.CO R.CO 
IN = S : 
PNH+ HOCI= us VG H,0. 
, 
Royal Microscopical Society, May 17.—Mr. E. M. 
Nelson, President, in the chair.—Mr. C. L. Curties exhibited 
and described a new electrically heated stage for the microscope, 
made by Reichert. It was constructed so as to be heated by 
the current from the ordinary electric lighting supply. By an 
ingenious automatic arrangement the stage could be maintained 
at any required temperature to within o-1° C.—Messrs. Watson 
and Sons exhibited a form of dissecting stage, designed by Mr. 
T. G. West, which could be used with any microscope without 
damaging the stage of the instrument when doing rough work.— 
The President called attention to some beautiful photographs of 
Mr. Grayson’s rulings, taken by Mr. Wedeles.—Dr. Sorby’s 
communication not being forthcoming, the President read a 
paper on the fine adjustment. He described the various forms 
which had been adopted from time to time, and said that in the 
course of his investigations he had discovered that Varley’s 
inventions had been ascribed to others, and that the long lever 
fine adjustment generally ascribed to Ross was really first made 
by Powell.—The President then called attention to the exhibi- 
tion of ‘‘ pond life” by Fellows of the Society and Members 
of the Quekett Microscopical Club. 
PARIS. 
Academy of Sciences, June 5.—M. van Tieghem in the 
chair.—On the development in series of the integrals of 
differential equations by Cauchy’s method, by M. Emile Picard. 
—Remarks on the formation of alcohol and carbonic acid, and 
on the absorption of oxygen by the tissues of plants, by M. 
Berthelot. Some remarks on a note in the previous number of 
the Comptes rendus, by M. A. Devaux. M. Berthelot recalls 
some experiments on the formation of alcohol made by him in 
1860, and emphasises the necessity of very careful manipulation 
in experiments of this nature. Thus the alcohol may be driven 
off by a current of hydrogen at 110’, if the carbon dioxide is to 
be determined, or in a rapid current of steam if the isolation of 
the alcohol only is aimed at. If the manipulation of the 
leaves is not carried out as rapidly as possible, alcohol is 
readily formed during the process.—On the molecular re- 
fractions, molecular dispersion, and specific rotatory power 
of the combinations of camphor with some aromatic alde- 
hydes, by MM. A. Haller and P. Th, Miiller. The substances 
studied would be represented by the general formula 
C=CHR 
SEE 2 
where R was CgH;, CgH,0.CH,, C;H,(C3H,), and CgH4(OCH,). 
The results of the experiments are given in a table showing the 
molecular refractions of each of these substances for the rays 
Na, H., Hg, H,, the molecular dispersion, and the specific 
rotatory power (a)p at 20°, all determined in toluene solution. 
Both the molecular refractions and dispersions deviate strongly 
from the values calculated from the usual moduli, and this 
peculiarity is still more marked in the specific rotatory power, 
which for camphor is about 42°, and for these aldehyde 
camphors is of the order of 500°.—Construction of a plane 
mirror of 2 métres diameter by mechanical methods, by M. P. 
