CHEMISTEY. 



107 



Iodide of silicium decomposes in water with 

 formation of silica and iodhydric acid, without 

 liberation of hydrogen or precipitation of 

 iodine. This reaction suffices to prove that its 

 composition is analogous to that of the chloride, 

 SiCU. Its analysis is performed by breaking 

 in a stoppered flask, and containing dilute am- 

 monia, a glass bubble .filled with the substance. 

 When decomposition ceases, the liquid is evap- 

 orated in the same flask over a water-bath, a 

 current of air being passed into it by means of 

 an aspirator, and the liquid produced by evap- 

 oration condensed in a cool receiver. "Without 

 the latter precaution part of the iodine would 

 be lost. After evaporation to dryness, the 

 residue is taken up by the condensed water, 

 filtered, and washed ; and, in order to obtain 

 the weight of the silica, it is merely necessary 

 to deduct, from the weight found, that of the 

 bubble. The iodine is precipitated in the filter- 

 ing liquid. Thus figures are found agreeing 

 with the formula SiI 4 . Following the excel- 

 lent process of MM. Sainte-Olaire Deville and 

 Troost, the density of its vapor was taken in 

 mercurial vapor. It was found indispensable 

 to fill the globe with carbonic acid, and sundry 

 precautions were used to prevent the reen- 

 trance of air. At the close of the experiment, 

 the globe proved to contain no free iodine. 

 The number obtained for the density was 19.12. 

 The theoretical value corresponding with the 

 formula SiI 4 , and with two volumes of vapor 

 is 18.56. These results complete the analogy 

 of iodide of silicium. with the chloride. v 



Per sulphide of Hydrogen. Dr. A. W. Hof- 

 mann has been investigating the constitution 

 of persulphide of hydrogen, taking advantage 

 of the fact that great quantities of the sub- 

 stance are produced in certain technical pro- 

 cesses at Dienze. He has succeeded in render- 

 ing it certain that there is a persulphide having 

 the formula H 2 S 3 . When a cold saturated so- 

 lution of strychnine in strong alcohol is added 

 to an alcoholic solution of persulphide of am- 

 monium, brilliant crystalline spangles soon ap- 

 pear, and, after twelve hours, beautiful orange- 

 red needles are formed, which, after washing 

 with cold water, are perfectly pure. They are 

 insoluble in water, alcohol, ether, and bisul- 

 phide of carbon ; in fact the author has found 

 no solvent from which they could be recrystal- 

 lized. Analysis leads to the formula C 2 iH 24 

 N 2 2 S 3 =C 2 iH 22 N 2 O 2 + H 2 S 3 . In contact with 

 sulphuric acid the crystals are decolorized, and, 

 on adding water, colorless, transparent oily 

 <lrops of persulphide of hydrogen are separated, 

 which, after some time, are resolved into sul- 

 phur and sulphuretted hydrogen. Quinine, 

 cinchonine, benzine, and some other alkaloids 

 gave no analogous compounds. (Proc. Royal 

 Society, vol. xvi., p. 437.) 



New Method of Sugar Manufacture. M. Le- 

 play's new process of extracting sugar from 

 beet-root juice, as well as syrups and molasses 

 of all descriptions, is thus alluded to in the 

 Chemical News : 



M. Leplay sought to extract the sugar from the 

 matters in question^ by transforming it into insoluble 

 sucrate of lime, which has not yet been made on an 

 industrial scale. This combination is effected in the 

 saccharine fluids treated, less by an addition of ready- 

 formed free lime, than by the aid of solutions of cal- 

 careous salts, and particularly of chloride of calcium, 

 and of caustic soda, which precipitates the lime, and 

 this combines and is precipitated with the sugar. 

 The sucrate of lime, after precipitation, is decom- 

 posed by means of carbonic acid, the soda in the 

 solution regenerated, and the carbonic acid obtained 

 as a secondary product in the formation of the chlo- 

 ride of calcium. When a solution of sugar in water 

 is saturated with all the lime which it is capable of 

 absorbing, and boiled, there is formed a white pre- 

 cipitate of sucrate of lime, which is redissolved on 

 cooling. The quantity of sugar thus eliminated is 

 only a small proportion of. that present, and the 

 greater part remains in solution when the precipitate 

 is separated from the liquid during ebullition. Fee- 

 bler still is the proportion of sugar that can be ex- 

 tracted from beet-root juice or molasses, and the 

 more impure the saccharine fluid is, the less consid- 

 erable is the separation obtained by this means. On 

 the contrary, the whole of the sugar may be precipi- 

 tated in the state of sucrate of lime, when in the solu- 

 tion already saturated with lime, a fresh quantity of 

 lime is separated in the nascent state, then the pre- 

 cipitation is independent of the degree of purity of 

 the saccharine solutions. Besides the juice of the 

 beet-root, the molasses of sugar-refineries are capable 

 of treatment by the process. The quantity of solu- 

 ble salts of lime present in the syrups, etc. , exerts an 

 influence on the proportion of calcareous salt which 

 should he added ; as these salts contain organic acids, 

 the soda is no longer found in corresponding quan- 

 tity, as chloride of sodium, but as carbonate of 

 soda in the ash obtained from the mother liquor 

 an important advantage. Tlie previous saturation 

 of the liquor submitted to treatment by pure lime, 

 "before the addition of the calcareous salt, is then 

 essential, since by this means a portion of the calca- 

 reous salt, which would be otherwise required, is 

 replaced by the cheaper material, lime. The sucrate 

 of lime precipitated is separated from the liquor, 

 washed with water, and decomposed by carbonic 

 acid. 



Analysis of British Waters. In an article 

 which was read before the Eoyal Institution 

 of Great Britain, on the 3d of April, 1868, by 

 Professor Frankland, "On the proposed Water- 

 supply for the Metropolis," he gives the fol- 

 lowing tables : 



Results of Analysis of Welsh, Cumberland, and Lon- 

 don Waters. 



100,000 PABTS OP WATEK GATE 



