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Hydrocarbon. C.H.

CAH. Propylene ?, Acetene Acrylic alcohol, the history of which we have endeavoured to sketch in the preceding pages, and in the study of which we are now engaged, is the third term of a series of alcohols, which is parallel to the ordinary alcohols of the formula

CnH2+202, and the prototype of which is ethylic alcohol. The acid corresponding to this alcohol is acrylic acid, as has been stated. Chemists are already acquainted with sereral homologues of acrylic acid, which stand to the series of fatty acids in the same relation which exists between our new alcohol and common alcohol. Cyanide of acryl, which is readily procured by the action of iodide of acryl upon cyanide of silver, but which as yet we have not been able to obtain in a state of perfect purity, when submitted to the action of potassa, will obviously furnish an acid, homologous to acrylic acid equally as cyanide of propyl is transformed into butylic acid.

We terminate this note with a synoptical table of the two homologous groups. Group of Alcohols.

Group of Acids.
C, H, O, C2 H, 0, Methylic Cg 04 (Carbonic ?) C, H, 04 Formic
C, H, O, C, H. 0, Ethylic C, H, OH

CA H, O, Acetic
Cg H 0, Acrylic Cô H, O, Propylic C6 H, 04 Acrylic C. HE O, Propionic
C, H, Og Cg H100, Butylic Cg Ho 04

Cg H, O, Butylic
Co H100g C10H120, Amylic Clo Hg Angelic Co H100, Valeric
C12H120, C12 H 140, Caproic C2 H1004

C9 H120, Caproic C14H14 Oz C14H160,

C14 H 2 O

C14H1404 Enanthylic C16H160, C16H18 0, Caprylic C16H24 0

C16 H160, Caprylic

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This table exhibits a considerable number of gaps, which the progress of science will not be long in filling up. Even now we have established by experiment that bromide of amylene suffers many changes, which are perfectly analogous to those which we have witnessed in the acryl series, and even the derivatives of olefiant gas appear to exhibit in many respects an analogous deportment.

February 14, 1856.

Dr. W. A. MILLER, V.P., in the Chair.

The following communication was read :

On Periodical Laws discoverable in the Mean Effects of the

larger. Magnetic Disturbances." -- No. III. By Colonel EDWARD Sabine, R.A., D.C.L., Treas. and V.P.R.S.

(Abstract.) In two previous papers bearing the same title as the present (Phil. Trans. 1851, Art. V., and 1852, Art. VIII.), the author showed, from the hourly observations of the magnetic Declination at Toronto and Hobarton, that the magnetic disturbances of large amount, and apparently irregular occurrence, commonly called magnetic storms, are found, when studied in their mean effects, to be governed by periodical laws of systematic order and regularity, and to exhibit periods whose duration is, respectively, 1, a solar day; 2, a solar year; and 3, a period of about ten of our solar years, corresponding both in duration and in the epochs of maximum and minimum variation, to the approximately decennial period discovered by Schwabe in the phænomena of the solar spots. In the present paper the author communicates the results of a similar investigation into the laws of the disturbances of the two other magnetic elements at Toronto, namely, the Inclination and the Total Force, derived from the hourly observations of the horizontal and vertical Forces during the five years from July 1843 to June 1848 ; affording, as he states, a full confirmation of the existence of periodical laws regulating the disturbances of the Inclination and Total Force corresponding to those which he had previously deduced from the disturbances of the other magnetic Element, viz. the Declination.

February 21, 1856.

The LORD WROTTESLEY, President, in the Chair.

The following communications were read:

I. “On the Thermal Effects of Fluids in Motion.” By Pro

fessor William Thomson, F.R.S., and J. P. JOULE, Esq., F.R.S. Received February 11, 1856.

A very great depression of temperature has been remarked by some observers when steam of high pressure issues from a small orifice into the open air. After the experiments we have made on the rush of air in similar circumstances, it could not be doubted that a great elevation of temperature of the issuing steam might be observed as well as the great depression usually supposed to be the only result. The method to obtain the entire thermal effect is obviously that which we have already employed in our experiments on permanently elastic fluids, viz. to transmit the steam through a porous material and to ascertain its temperature as it enters into and issues from the resisting medium. We have made a preliminary experiment of this kind which may be sufficiently interesting to place on record before proceeding to obtain more exact numerical results.

A short pipe an inch and a half diameter was screwed into an elbow pipe inserted into the top of a high pressure steam-boiler. A cotton plug placed in the short pipe had a fine wire of platina passed through it, the ends of which were connected with iron wires passing away to a sensitive galvanometer. The deflection due to a given difference of temperature of the same metallic junctions having been previously ascertained, we were able to estimate the difference of temperature of the steam at the opposite ends of the plug. The result of several experiments showed that for each lb. of pressure by which the steam on the pressure side exceeded that of the atmosphere on the exit side there was a cooling effect of 0.2 Cent. The steam, therefore, issued at a temperature above 100° Cent., and, consequently, dry; showing the correctness of the view which we brought forward some years ago * as to the non-scalding property of steam issuing from a high pressure boiler.

II. “On the Bromide of Titanium.” By F. B. DUPPA, Esq.

Communicated by A. W. HOFMANN, Ph.D., F.R.S. &c.
Received February 1-1, 1856.

A comparison of the boiling points of corresponding chlorine and bromine compounds, led Prof. Kopp to the interesting discovery, that on the average their boiling-points rise 32° C for every equivalent of bromine which is substituted for an equivalent of chlorine.

Boiling

point. Difference. Chloride of ethyl, CAH, CI

11°C.

30.
Bromide of ethyl, C,H, Br 41°C.
Dichlorinetted ethylene, C, H, cl, 67°C.

66=2 x 33.
Dibrominetted ethylene, C, H, Br, 1330-6C.
Terchloride of phosphorus, P Clz . 78° C.

32. Terbromide of phosphorus, P Brg. 175° C. If this difference be constant for all chlorine and bromine compounds, it becomes obvious that very important inferences in respect to the atomic constitution of these substances may be derived from the determination of their boiling-points. This result has, in fact, been happily applied by Prof. Kopp, as a criterion to determine the equivalent of silicium, a matter of such uncertainty as to have led to the admission of not less than three formulæ for silica

}
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Sio

SiO2
SiO3.

From the difference between the boiling-points of chloride (59° C.) * See letter from Mr. Thomson to Mr. Joule, published in the Philosophical Magazine, Nov. 1850.

and that of bromide (153° C.)-a difference which amounts to 94=3 x 31}-Kopp derives the formula

SiC), and SiBry as representing the atomic constitution of the chloride and the bromide of silicium, and he accordingly fixes the equivalent of silicium at 21:3.

In order, however, to prove the general validity of Kopp's observations, it was necessary to re-examine the boiling-points of corresponding chlorine and bromine compounds which exhibited discrepancies, and to extend the inquiry to as great a number of new compounds as possible.

Mr. Francis Baldwin Duppa has, at my suggestion, undertaken an investigation of this subject, and has already obtained some valuable results, whieh I beg to communicate to the Royal Society.

The bromine-compound of titanium was unknown. Mr. Duppa has produced this substance by passing a current of bromine over an intimate mixture of pure titanic acid and carbon. The reaction takes place at a bright red heat, and furnishes a brown liquid, which solidifies in the receiver to a crystalline mass. Distilled with an excess of mercury, which removes any free bromine that

may

be present, the bromide of titanium presents itself as an amber-yellow compound, exhibiting a magnificent crystalline structure ; it attracts moistère with the greatest avidity, and is converted into titanic and hydrobromic acid. Bromide of titanium has a specific gravity of 2.6. The fusing-point was found, 39o. The boiling-point was examined by Mr. Duppa with a considerable quantity of substance, the purity of which had been ascertained by analysis. It was observed to be 230° C. The boiling-point of the chloride of titanium, as observed by Dumas, and confirmed by Mr. Duppa, is 135o. The difference, 230— 135=95=3x31}, is exactly the same as that observed between the boiling-points of chloride and bromide of silicium.

This observation furnishes an additional support to the analogy of silicium and titanium, while it points unequivocally to the formulæ

TiCl, and TiBrz as representing the atomic constitution of these two compounds.

VOL. VIII.

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