55- 



NA TURE 



[Oct. 2, 1884 



hence that the act of solution is still attended at these temperatures 

 hy chemical combination between the salt and the water. These 

 results when plotted out give a line which is nearly parallel to 

 the curve of solubility between these limits of temperature. 



On Calcium Sulphide and Sulpho-carbonate, by V. H. Veley, 

 M.A. — Calcium oxide, free from metals of the iron group, was 

 obtained by heating perfectly transparent crystals of Iceland 

 spar in a current of hydrogen. This oxide was hydrated in a 

 damp atmosphere free from carb >nic acid. The hydroxide was 

 I to 6o° C, and hydric sulphide passed over it. The 

 resulting calcium sulphide and water were weighed, and the 

 synthetic results thus obtained were found to agree closely with 

 the results of the analysis of the calcium sulphide. It is worthy 

 of note that perfectly dry calcium oxide is unaltered by the 

 passage over it of perfectly dry hydric sulphide, and generally 

 the formation of calcium sulphide proceeded the more 1 pidly 

 lh" greater the quantity of water originally present in the 

 hydroxide. This result may be due to the formation, at first, 

 either of the hydrosulphide, or the hydroxy-hydrosulphide 

 (CaOH,SH), and the subsequent conversion of either of these 

 substances into the sulphide. The calcium sulphide, prepared 

 as described above, was moistened with water, and hydrogen 

 saturated with carbon bisulphide passed through it. It gradually 

 turned yellow, and finally red, and on exhaustion with cold 

 water a red solution was obtained, from which, on evaporation 

 in vacuo, red, deliquescent, prismatic crystals separated. The 

 composition of these crystals was found by analysis to correspond 

 with the formula Ca(OH) 2 ,CaCS,rfLO. A solution of this 

 substance gave characteristic precipitates with metallic salts, 

 which the author intends to examine more minutely. 



On the Velocity of Expl vom in Gases, by H. Ii. Dixon, 

 M.A. — MM. Benhelot and Vieille have shown that in oxygen 

 and hydrogen and several other mixtures of gases the " explosive- 

 wave" is propagated at a velocity closely approximating to the 

 mean velocity of translation of the gaseous products of combus- 

 tion calculated on the assumption that all the heat of the reac- 

 tion is contained for the moment in the products formed. The 

 mean of a number of determinations with electrolytic gas gave 

 a velocity of 2810 m. per second, the calculated mean velocity 

 nf the steam molecule formed being 2831 m. per second. 

 These experimenters found that carbonic oxide exploded either 

 with oxygen or nitrous oxide did not agree with the rule. The 

 author has shown that steam is necessary for the burning of 

 carbonic oxide both with oxygen and nitrous oxide, and that, as 

 the proportion of steam is increased, the rate of inflammation is 

 also increased. Experiments made in a lead tube 55 m. long 

 and 13 mm. in diameter entirely confirmed MM. Berthelot and 

 Vieille's experiments with hydrogen and oxygen. The rate ol 

 the " explosive wave " was found to be 2S17 m. per second as the 

 mean of several closely cone rdant experiments at io° C. With 

 carbonic oxide and hydrogen nearly dry, the explosive wave 

 was not established until the flame had traversed a distance oi 

 700 mm. from the firing-point : the explosive wave was found 

 to have a velocity rather over 1500 m. per second. After the 

 explosion a fine layer of carbon was found to cover the inside 

 of the explosion-tube, showing that at the enormous tempera- 

 ture of the explosive wave carbonic oxide is decomposed into its 

 constituents. 



A Theory nf Solution, by W. \V. J. Nicol, M.A., B.Sc— 

 The author has proposed the theory that the solution of a salt 

 in water is a consequence of the attraction of the molecules of 

 water for a molecule of salt exceeding the attraction of the 

 molecules of salt for one another. It follows, therefore, that, as 

 the number of dissolved salt molecules increases, the attraction 

 of the dissimilar molecules is more and more balanced by the 

 attraction of the similar molecules : when these two forces are 

 in equilibrium, saturation takes place. Any external cause tend- 

 ing to alter the intensity of either of these two opposite forces 

 disturbs the condition of equilibrium, and further solution or 

 solidification ensues The contraction which occurs on the 

 solution of a salt in water has been regarded as strong evidence 

 in favour of chemical combination having taken place, but the 

 author finds that a further contraction takes place on further 

 dilution, even when the number of water molecules per salt 

 molecule is far in excess of the number in the cryohydrates. 



On the Manufacture of Soda and Chlorine, by W. Weldon, 

 F.R.S. — Chlorine is at present manufactured exclusively from 

 hydrochloric acid, obtained as a by-product of the manufacture 

 of so. la by the Leblanc process. It is owing to this that the 

 Leblanc process has been able to withstand the severe com- 



petition of the ammonia process, which gives soda much more 

 cheaply than the Leblanc process, but does not yield either 

 hydrochloric acid or chlorine. The author announces a process 

 for the preparation of chlorine in connection with the manufac- 

 ture of soda by the ammonia process. The new process consists 

 in decomposing by magnesia the ammonium chloride of the 

 ammonia-soda process, adding magnesia to the resulting solution 

 of magnesium chloride, and so obtaining solid oxychloride of 

 magnesium, which, heated in a current of air, gives off chlorine 

 and leaves magnesia. 



On the Diamond-bearing Rocks of South Africa, by Prof. Sir 

 Henry E. Roscoe, President. — After an introductory description 

 of the geological and physical aspects of the remarkable 

 diamond-bearing deposits at Kimberley and elsewhere, the 

 author gave the chemical composition of these rocks. The most 

 noteworthy feature of the examination of these rocks is the dis- 

 covery in the so-called diamond earth of a volatile crystalline 

 hydrocarbon, soluble in ether, which seems to confirm the hypo- 

 thesis that the Carboniferous shales, which are penetrated by the 

 diamond-bearing pipes, have been the source of the carbon n,» 

 found in the crystalline state in the diamond. The physical 

 structure nf the ash or incombustible portion of the diamond is 

 of a very singular character, and has hitherto n it been examined. 

 A careful study of the diam ind ash may possibly throw light on 

 the important question of the mode of formation of the diamond. 



Colour of Chemical Compounds, by Prof. Carnelley, D. Sc. 

 — The colour of chemical compounds is conditioned by at 

 least three circumstances, viz. (1) temperature (Ackroyd) ; 

 (2) the quantity of the electro-negative element present in a 

 binary compound (Ackroyd) ; (3) the atomic weights of the con- 

 stituent elements of the compounds (Carnelley) ; and that in such 

 a way that the colour passes or tends to pas» through the follow- 

 ing chromatic scale — white or colourless, violet, indigo, blue, 

 green, yellow, orange, red, brown, black — either by (1) rise of 

 temperature, or (2) increase of the quantity of the electro- 

 negative element in a binary compound, or (3) with increase of 

 the atomic weights of the elements A, B, C, &c, in the com- 

 pounds Ax \<y, Br \<y, Cx Rj', &c., in which R is any element 

 or group of elements, whilst A, B, C, &c, are elements belonging 

 to the same sub-group of MendeleefTs classification of the elements. 

 Tables accompany the paper in illustration of the above. Out of 

 426 cases in which the third of the above rules has been applied, 

 there are but sixteen exceptions, or less than 4 per cent. Finally 

 a theoretical explanation is given which appears to account in a 

 very simple manner for the influence of the above three circum- 

 stances on the colour of chemical compounds. 



Notes of Nitrification, by R. Warington. — He considered 

 the present position of the theory of nitrification, and next gave 

 a short account of the results of recent experiments conducted 

 by him at Rothamsted. Messrs. Schloesing and Miintz, early 

 in 1877, showed that nitrification in sewage and in soils is the 

 result of the action of an organised ferment, occurring in soils 

 and impure waters. The experiments of the author have con- 

 firmed the soundness of this theory. The evidence for the fer- 

 ment theory is now very complete. Nitrification in soils and 

 water, is strictly limited to range of temperature within which 

 the vital activity of the living ferment is confined. It proceeds 

 with slowness at o°, is at a maximum at 37 , and ceases at 55 . 

 Nitrification is also dependent on plant food suitable for 

 organisms of low character. Further proof of the ferment theory 

 is that antiseptics are fatal to nitrification. Heating sewage to 

 boiling-point, or soil to the same temperature, effectually prevents 

 it. Finally, nitrification can be started in boiled sewage or other 

 sterilised liquid by the addition of a little surface soil or a few 

 drops of a solution already nitrified. These nitrifying organisms 

 have as yet received but little microscopical study. 



On the Liquefaction of Oxygen and the Density of Liquid 

 Hydrogen, by Prof. Dewar, F.R.S. — The problem of liquefying 

 oxygen and hydrogen, and consequently others of the so-called 

 permanent gases, having been solved by Cailletet and Pictet, the 

 author has since been employed studying the physical characters 

 of these gases in the condensed state. The critical pressures 

 and temperatures at condensation have been determined, and 

 the relation of one to the other is shown to be constant. The 

 merits of various cold producers that could be employed in the 

 process were discussed. Condensed ethylene he c insidered the 

 best, then condensed nitrous oxide and carbonic acid. The 

 lowest temperature that could be obtained by carbonic acid is 

 about 115° C, and by nitrous oxide 125 C. 



On the Production of Permanent Gas from Paraffin Oils, by 



