Sept. 7, 1882] 



NATURE 



467 



from which by contact with water hydrogen peroxide is produced 

 as a secondary product. The views of Traube (Chem. Soc. yourn. 

 18S2, 795) are criticised. The author prefers to represent per- 

 oxide of hydrogen as oxygenated water, thus, OOH s , rather than 

 hydrogen dioxide, a representation which is considered to explain 

 it- properties and reactions more adequately. 



Metallic Compounds containing Bivalent Hydrocarbon Radicals, 

 P.irt III., by Professor I. Sakurai, F.C.S., Tolrio University, 

 Japan. — By acting on monomercuric methylene iodide Hg(CH 2 ) 

 I, (described in the Report of 1S80) with mercuric chloride, 

 monomercuric methylene chloriodide HgCII 2 ClI is obtained. 

 This compound is acted upon by iodine, and yields mercuric 

 iodide and methylene chloriodide CHJC1, which is a liquid 

 boiling at 109 and having a specific gravity of 2 '49 at 20°. 

 The formation of this latter substance shows that monomercuric 

 methylene chloriodide has the following constitution, CICIIoHgl. 

 Attention is drawn to the fact that the boiling point of the 

 methylene chloriodide is approximately the mean of the boiling 

 points of methylene chloride and iodide. 



Hydrocarbons of the Formula (C S H 8 ),„ by Prof. W. A. 

 Tilden, F.R.S. — An account was given of the existing knowledge 

 of isoprene, and the author finds that it forms a tetrabromide 

 C 5 H 8 Br 4 , a liquid which cannot he distilled without decomposi- 

 tion. When oxidised by nitric acid isoprene yields oxalic acid, 

 but form and acetic acids are produced when chromic acid is 

 employed. Since isoprene can be converted into caoutchouc, 

 experiments have been made to ascertain whether this hydro- 

 carbon could be obtained from other sources, and inasmuch as 

 isoprene can be converted into a true turpentine, this latter 

 su stance was studied with this object. The author found that 

 when turpentine is passed through a red-hot tube a mixture of 

 hydrocarbons is obtained, from which a small quantity of a 

 volatile liquid, having the composition and properties of isoprene, 

 has been isolated. The formula: assignable to the eight po-sible 

 compounds having the composition of C 5 H 8 was discussed, as 

 alsn was their relation to the terpenes. 



J lie .-£ 'orthometer, an Instrument for Correcting the Measure 

 of a Gas, by A. Vernon Harcourt, M.A., F.R.S. — The object of 

 this instrument is to simplify the method of reducing the volume 

 of a gas to normal conditions of temperature and pressure. The 

 instrument consists of two narrow tubes, the one open above, 

 the other terminating in a bulb, whose capacity, including that 

 of the stem down to the first graduation, is 1000 of the units with 

 which the stem is divided ; both tubes are connected below with 

 a reservoir from which mercury can be driven up the tubes by 

 the pressure of a screw. When the mercury stands at the same 

 level in the two tubes, the air in the closed tube, which at 0° and 

 760 mm. occupies 1000 volumes is under existing atmospheric 

 pressure. It has also the temperature of the surrounding air, and 

 is therefore under the same conditions as the gas in any vessel 

 near it. The volume read on the aarorthometer is '.0 1000 as the 

 observed volume of the gas in the measuring vessel is to its 

 normal or corrected volume. For the case of measuring gas 

 ovtr water, or in pre ence of water, the aerorthometer is charged 

 with a drop of water. For technical purposes the graduation 

 " 1000" denotes the volume which the inclosed air occupies at 

 30 inches Bar. and 60° Fahr. 



A Revision of the Atomic Weight of Rubidium, by Charles T. 

 Heyc >ck, B.A. — The object of this revision is to ascertain 

 whether the atomic weight of rubidium can be brought into 

 accord with Prout's hypothesis. To this end pure chloride and 

 bromide of rubidium have been prepared, and the amount of 

 chlorine and bromine contained in these, determined by titrating 

 with silver nitrate in a manner identical with that employed by 

 Stas in his classical researches. The results obtained from 

 the chloride give an atomic weight of 85"344 for rubidium, 

 whdst those obtained with the bromide, which the author gives 

 with some reserve, show the atomic weight to be S5'387. The.-e 

 results show that, at present, rubidium cannot be regarded as 

 conforming to Prout's hypothesis. 



Method of obtaining- Ammonia from Shoddy and Allied 

 Substances, by W. Marriott, F.C.S.— Adescriptionof the method 

 of burning shoddy moistened with soda in such a way as to 

 collect the ammonia from the gases produced, and also utilise the 

 combustible gases formed at the same time. 



On the Application of the Diamond to Mineralogical and 

 Chemical Analysis, by Prof, von Baumhauer. — The author after 

 describing the various modifications of the diamond, gave an 

 account of tome methods in which the diamond might with ad- 

 vantage be employed in mineralogical and chemical analysis for 



the purpose of reducing hard substances to a fine state of 

 division. 



On the Occurrence of Tellurium and Selenium in Japan, ly 

 E. Divers, M.D., Professor, and Masachika Shimos, Student of 

 Chemistry in the Imperial College of Engineering of Japan. 

 — At the last meeting of the Association a communication 

 was received from Dr. Divers in whi"h it was shown that these 

 elements are found in Japanese sulphuric acid. In this paper a 

 description is given of the sulphur used in the manufacture of the 

 acid, it differs from ordinary ~ulphur by being reddish-yellow in 

 colour, and is known as sekiriuscki, or massive red sulphur, and 

 is obtained from Iwoshima (sulphur island), a specimen of this 

 red sulphur was found to contain 0*17 per cent, of tellurium and 

 o'o6 per cent, of selenium. It is a matter of some interest that 

 tellurium is found associated with sulphur in this state, as it is 

 more usually associated w ith sulphur in a state of combination 

 with the metals. Analysis of the mud-like deposit found in the 

 vitriol chambers show it to contain some 10 per cent, of selenium 

 and I 2 per cent, of tellurium, and the sulphuric acid was found 

 to contain 0^37 grains of tellurium and C15 gram selenium per 

 liter. Attention is drawn to the fact that whilst the relative 

 proportion between the quantities of tsllurium to the selenium is 

 as S to 2 in the sulphur, and as 5'5 to 2 in the liquid, it is as I 

 to 9 in the deposit. This is easily explained by the fact that 

 finely divided tellurium easily undergoes oxidation in presence of 

 water and air whereas selenium is not so affected. Selenium 

 and tellurium have been obtained by distilling the deposit in 

 clay retorts. 



On the Action of the Component Salts as Nuclei on Super- 

 saturated Solutions of certain Double Salts, by John M. 

 Thomson, F.R.S. E., F.C.S.— In a paper published in the 

 Journal of the Chemical Society, May, 1S79, the author has 

 shown that if a mixture of dimorphous salts be taken, a separa- 

 tion may be effected by touching the solution with a crystal ot 

 one or other of the salts ; a separation depending on the relative 

 solubilities of the two salts. The investigation has been extended 

 to supersaturated solutions of double salts, and the action 

 upon these of the components of the double salts. Experi- 

 ments have been made with solutions of double chit rides of 

 mercury and ammonium, of mercuric chloride and ammonium 

 bromide, of mercuric and potassium iodides, and of mercuric 

 ammonium bromides. In these cases it has been found that the 

 salt of the heavy metal is invariably active in producing crystal- 

 lisation, whereas that of the alkali constituent is inactive. It has 

 also been observed that the true prismatic forms of mercuric 

 chloride and bromide produce crystallisation at once ; but that if 

 crystals of other forms are employed, as when obtai ed by 

 deposition at a higher temperature, then the re^lt is not always 

 so defined. This is no doubt due to the fact that the first form 

 of the heavy metallic salt is more nearly allied to that of the 

 double salt. It appears, therefore, that these double salts of 

 monobasic acids, although forming good s U p e r f aturated solu- 

 tions, are not so firmly united together as to resist the dis- 

 turbing influence of certain of their constituents, yet the disruption 

 is not sufficient to produce a decomposition, and so a deposit of 

 the double salt is obtained. Experiments w ith the double salt 

 of mercuric cyanide and ammonium chloride, show that each 

 constituent is active. In the case of the alums, the double 

 phosphates and arseniates neither constituent is active. With 

 Lefort's salts, viz. double sulphates of copper and zinc, both 

 constituents are active, the zinc salt produces the more rapid 

 crystallisation, but the double salt is deposited in each case. In 

 the case of the double tartrates of sodium and potassium it was 

 found that the potassium salt is inactive, whilst the sodium salt 

 is active. An examination of the crystals showed them to have 

 the composition of Rochelle salt ; and since the nucleus in no 

 w ise resembled this salt in form, it would appear that rochelle 

 salt is probably dimorphous. The activity of sodium tartrate 

 is probably due to its being less soluble than potassium tartrate. 

 In the case of the double citrates of these metals both constitu- 

 ents are active, w hilst with the citrates of magnesium and sodium 

 both constituents are inactive. These results show that the 

 union in the double salts of monobasic acids is more of a 

 molecular character, inasmuch as they suffer disruption more 

 easily than do those formed of acids having a higher basicity, 

 such as the alums and phosphates, where there is a firmer union 

 of the constituent salts. 



The Decomposition by heat of Potassium Chlorate, by Profess or 

 I. M. Crafts and A. Rilliet. — The authors have observed that 

 the addition of metallic silver reduced from the chloride aids 



