A 



114 Scieiitijic Intelligence. 



mean of four experiments, two by reduction and two by oxydation', 

 Marchand found 1150'6; as a mean of eight experiments, five by 

 reduction and three by oxydation, Schneider found 1150-78, the first 

 series giving 1150-39, the second 1151'17. We may therefore safely 

 infer that the equivalent of tungsten does not differ by a unit from 1150. 

 Ann, der Chemie und PharmarAe^ Feb.^ 1851, 262. 

 5. Action of Light upon the lodid of Ethyl, — Frankland has stud- 

 ied the action of light upon the iodid of ethyl and has discovered a 

 new and remarkable analogy between hydrogen and the homologous 

 radicals, rnelhyl, ethyl, amyl, &c. lodohydric acid as is well known 

 when exposed to the light in a well closed flask gradually becomes 

 brown from the separation of iodine, and the decomposition is continu- 

 ous if the free iodine be removed as fast as formed. Iodid of ethyl is 

 also discolored by exposure to light and the products of its decomposi- 

 tion under these circumstances form the subject of Frankland''s inves- 

 tigation, A number of glass balloons containing each about ten ounces 

 were filled with mercury and inverted into a cistern of the same metal ; 

 a few drops of iodid of ethyl were introduced into each balloon by 

 means of a pipette and the balloons were then exposed to the sun's 

 rays. The surface of the mercury was speedily covered with a thin 

 layer of subiodid which subsequently became proliodid while bubbles 

 of gas were evolved so as gradually to expel the mercury from the 

 balloon; the action was greatly increased by employing a parabolic 

 reflector to concentrate the rays of light, the temperature never being 

 allowed to rise as high as the boiling point of the iodid, Vl'GC. After 

 a few hours the balloons were filled ^ the gas contained was then allow- 

 ed to stand over a solution of sulphid of potassium to absorb the vapor 

 of iodid of ethyl and afterward submitted to analysis: it was found to 

 consist of 



Ethyl, « - (C4H5) - ' . - 67-76 

 Hydruret of ethyl,. (C4H5, H) . - 17-90 



defiant gas, - (C^Hi) . . 14-34 



The decomposition of the iodid in the presence of mercury noay 

 therefore be represented by the equation, C4.H5l-|-Hg=C4H5-|-Hg I- 

 A small portion of the elhyl is at the same time decomposed into 

 hydruret of ethyl and olefiant gas, 2C4H5=C4H5, H-j-CiHi. 



It appears therefore um the action of light upon the iodid of ethyl 

 is precisely similar to its action on iodid of hydrogen, and furthermore 

 thai the decomposition v/hich here takes place is analogous to that 

 which the iodid of ethyl undergoes at a^igh temperature in presence 

 of zinc. The presence of water was found to have no influence on 

 the products of the decomposition of iodid of ethyl by the sun's rays. 

 The author suggests the employment of iodid of ethyl as an actinome- 

 ler or instrument to measure the intensity of the chemical action of the 

 sun's rays ;" a very faint and diffuse light is sufficient to evolve a con- 

 siderable volume of gas which might be easily measured and corrected 

 for temperature, pressure, and tension of the vapor of undecomposed 

 iodid. The*author closes Ins most interesting memoir with ifn elabo- 

 rate, and as it appears to us, most sudcessfuf defence of his views of 

 the nature of the J)ydro-carburets,C2H3, CiHe, and C^Yib.—Ann^der 

 Chemie und Pharmacie^ Ixxvii, 22 L 



