Intelligence and Miscellaneous Articles. 473 



by Professors Gauss and Weber, being the First Annual Keport of 

 the Magnetic Association. An introduction, from the pen of Gauss, 

 on the "irregular Variations of the Terrestrial Magnetic Force, is 

 succeeded by " Remarks on the Arrangement of Magnetical Obser- 

 vatories, and Description of the Instruments to be placed in them," 

 by Weber; which is followed by a minute account of the " Method 

 to be pursued during the terms of Observation," by Gauss. This is 

 succeeded by an " Extract," also by Gauss, " from the daily Obser- 

 vations of Magnetic Declination during three years at Gottingen," 

 and a " Description of a small portable apparatus for measurmg the 

 absolute intensity of Terrestrial Magnetism, and Explanations of 

 the six graphical Representations and of the Table of Results." 

 Our readers will remember the Report to the Council of the Royal 

 Society of a Joint Committee of Physics and Meteorology " on the 

 establishment of fixed Magnetic Observatories and the equipment of 

 an Antarctic Expedition for Magnetic Observations," which appeared 

 in the Philosophical Magazine for February last, and to which we 

 may refer those who may not have already become acquainted with 

 the value and bearings of the work of Gauss and Weber, which now 

 first appears in the English language. 



The Part, which is illustrated by Ten Engravings, also contains 

 a highly valuable memoir by Professor Heinrich Rose on the Com- 

 binations of Ammonia with Carbonic Acid ; and another by Melloni 

 on the Polarization of Heat. 



PREPAR.\TION OF BICHLORIDE OF CARBON. BY M. REGNAULT. 

 M. Regnault prepared the proto-chloride of carbon, which, how- 

 ever, according to French equivalents, is described as CCl-, accord- 

 ing to Faraday^'s process ; he states that he found its boiling point to 

 be 248" instead of 170", as mentioned by Faraday; the density of 

 the vapour he ascertained to be 5-8, and therefore he considers it as 

 composed of C^ Cl«, and it belongs, he says, to the series of chloride 

 of aldehyde,— that is, to a series of which it contains only two out of 

 three elements,— but then this is explained by the doctrine of substitu- 

 tions— "C'est I'hydrogene bicarbone C^ H«, dans lequel I'hydrogene 

 est remplace par son equivalent de chlore." It appears to me that it 

 would be quite as consistent with sound philosophy, and attended 

 witii the additional advantage of somewhat extending the doctrine of 

 substitutions, if we were to say, that water belongs to the series of 

 sulphurets of mercury in which the sulphur is replaced by its equivalent 

 of oxygen, and the mercury by its equivalent of hydrogen. 



M. Regnault appears, however, to have succeeded in preparing the 

 dichloride of carbon, a specimen of which, as an accidental product, 

 was examined by Mr. Faraday and myself. He procured it by re- 

 peatedly passing the proto-chloride tiirough a tube heated to red- 

 ness ; the dichloride condenses in the coldest parts of the tube in 

 very 'fine silky needles, which are to be separated by a;ther; when 

 resiiblimed it is quite pure. This substance is nearly inodorous ; it 

 is difficult to hit upon the exact degree of heat for its preparation ; 

 if it be too great, tiic decomposition is complete and charcoal is de- 

 posited.— 22. P. An. de Ch. et dc Ph. Ixx., 105. 



