Came}. Chemical Notices from Foreign Souvces. 35
At an_ early meeting of the Chemical Society, next . the green tint of hydrocarbons burning with an excess of
session, I hope to communicate the details of these and air, but the flame is very unsteady, and the ignition is
other experiments with regard to processes of slow oxida- :asily communicated to the jet which introduces the gas.
tion. Meantime the publication of this note will much The same accident happens if the pressure of gas is weak,
oblige.—I am, &c., } and can only be avoided by partially closing the vents to
increase the draught. In the author’s improved lamp
:here are no side openings; the air enters between the foot
of the lamp and the bottom of the tube, which can he
raised or lowered at pleasure, 6 to 7 m.m. being sufficient
‘or admitting the largest quantity of air necessary. The
shortening of the hollow cone and the combustion of the
zas at the base of the flame are thus easily effeGted. To
avoid the oscillations of the flame and the ignition of the
gas at the inferior aperture (“striking down”), the inventor
 places at the summit of the tube, two small vertical
plates at right angles to each other, dividing the exit
aperture into four parts. In place of the hollow cone there
are then four smaller cones. The author then gives an
analysis of the produds of combustion, A very pure and
-ntense mono-chromatic light may be obtained by placing
1 bead of sodium chloride in the flame of the lamp thus
nodified.
Etherification of Hydrobromic Acid.—A. Villiers.—
The following results are arrived at :—The limit of etheriication
 is not equal to that corresponding to the organic
acids. The limit is not fixed, but rises with the temperature.
 The etherification ceases completely in mixtures
containing a certain proportion of water. The limit of
lilution beyond which the etherification cases is not fixed,
and rises with the temperature. The two latter fads may
>e explained by the existence of definite hydrates of hydrosromic
 acid, and by the dissociation of these hydrates
ander the action of an elevated temperature.
A Hydrated Methyl Iodide.—M. de Forcrand.—The
compound obtained has the composition C,H;I,HO, The
author has prepared similar hydrates of chloroform, ethyl
sromide, and ethyl iodide.
The Artificial Reproduction of Analcime.—A. de
Schulten.—This mineral has been reproduced by heating
1 solution of sodium silicate along with aluminous glass
to 180° to ¥go° in a closed vessel. The operation lasts
sighteen hours. The produ& thus obtained agrees with
the natural mineral in its optical and chemical characters.

Comptes Rendus Hebdomadaives des Séances, I Académie
des Sciences. No. 25, June 21, 1880,
Effects of the Reversal of Photographic Images
dy the Prolongation of Luminous Acéion.—]. Jamin.
—Photographic images may be reversed, and pass from a
negative to a positive by the prolonged acion of the light
to which they owe their origin. This reversal is produced
most readily in images of the sun on account of its enotmous
 radiant power. But other reversals are possible, and
2ven easy. Thus, besides solar images of o'10 metre in
diameter showing the sun with a white disc and black
spots, the author has obtained landscapes, presenting the
abje@s as they are. The time of exposure is from one to
three hours. He has also produced counter types of the
same nature as the original type; positive, if the type is
positive, and negative if it is negative. In these photographs
 the same spediral rays which give at first the negative
 image effect its conversion into a positive image.
formation-heat of the Oxides of Nitrogen and
those of Sulphur.—M. Berthelot.—The author discusses
‘he agreements and the differences between his thermochemical
 determinations and those of Prof. Thomsen.
For the formation-heat of SO; he gives as the mean of
three determinations +34 63. This result applies equally
to octahedral, prismatic, and insoluble sulphur,
Luminous Spectrum of Water Vapour.—Dr.
Huggins.—The author gives a table of the wave-lengths of
:he principal rays of the luminous spectrum of water vapour.
Proportion of Carbonic Acid in the Air: in Reply
to M. Marié Davy.—]. Reiset.—The writer maintains
:he accuracy of his results, asserting that he has found a
variation between the extreme proportions of 71 per
100,000. The minimum, 27°99, was found July 10, 1873,
in a field of barley and lucerne, The maximum, 3516,
occurred at Paris, January 27, 1879.
New Meteoric Mineral, with Information on the
fall of Meteorites in Iowa, May, 1879.—]J. Lawrence
Smith.~—The meteorite in question, to which Prof. Smith
gives the name of peckhamite, is—
Silica .. .. .. +. .. 49°59
Ferrous oxide .. .. .. 1701
Magnesia .. .. .. .. 3251
99°IT
At least 3000 fragments of the Iowa meteorite have been
discovered, their joint weight amounting to 30 kilos.
They consist of nickel iron, with very small quantities of
=arthy matter.
Certain Modifications in the Construction of the
Bunsen Lamp and of Mono-chromatic Lamps.—A.
Terquem.—The author sums up the following defeés in
the Bunsen burner. The flame is hollow in almest the
whole of its length, and the temperature is not uniform.
The entrance of air can only be increased within the
limits permitted by the total opening of the vents at the
base of the tube. Ii the air enters in a great quantitv t'e
Aame is shortened. the hollow cone contracts. and ta es

Biedevmann's Central-Blatt fiir Agrikultur-Chemie.
February, 1880.
The Reversion of Phosphates and the Behaviour
of Phosphoric Acid in the Soil.—H. Joulie, H. Albert,
and Dr. Vollbrecht.—An examination of the fact that a
part of the phosphoric acid in superphosphates originally
soluble in ammonium citrate becomes gradually insoluble.
The authors incline to the opinion that finely-ground
phosphates, or phosphates from which only one-third of
their lime has been withdrawn by means of sulphuric acid,
3ive a better result when composted with farm-yard
nanure, peat earth, &c., than ordinary superphosphates.
The great proportion of sulphate of lime in superphosphates
 may easily lead to undes red results.
Agricultural A&ion of Reverted Phosphoric Acid
and Neutral Phosphate of Lime.—Prof. A. Petermane,
Dr. M. Fleischer. Dr. E. Wein, and Dr. de Leeuw.—On
:hese questions there is still much uncertainty. Aluminic
and iron phosphates seemed in some experiments to have
a more beneficial a®ion than tribasic lime phosphate. On
light, calcareous soils reverted phosphoric acid is. found
2qual, if not superior, to such as is soluble in water.
Digestibility and Nutritive Value of the Locust
Bean or Carob.—Dr. H. Weiske.—In experiments made
1pon sheep it was found that the carobs, though eagerly
:aten, depressed the digestive power of the animals.
Determination of the Commercial Value of Grai .
—Prof. E. Wollny.—The specific gravity of grain is ot
ess value than the absolute weight and size of the invidual
 grains.