570 



NATURE 



{Oct. 13, 1887 



(2) The order of solubility of two or more isomeric compounds 

 is independent of the nature of the solvent. This has been ex- 

 perimentally proved, more particularly in the case of meta- and 

 paxa-nitraniline, the solubility of each of which in thirteen dif- 

 ferent solvents has been determined. Also by a considerable 

 number of cases taken from literature. 



(3) The ratio of the solubilities of two isomers in a given 

 solvent is constant, and is therefore independent of the nature of 

 the solvent. So that — 



Solubility of A in any solvent 

 Solubility of B in the same solvent ' constant. 



This has been proved for meta- and para-nitraniline in respect 

 of thirteen different and very varied solvents. 



Alcohol and Water Combinations, by Prof. Mendeleef — The 

 author looks upon solution as implying a definite chemical com- 

 bination liable to alteration and to decomposition at ordinary 

 temperatures. He has also examined the phenomena at low 

 temperatures where cryohydrates are formed, and finds the same 

 agreement with his adopted formula. At low temperatures he 

 has obtained solid compounds of alcohol and water containing 

 17 '56, 46 '04, and 88-46 per cent, of alcohol respectively. The 

 investigations have been extended to various mineral acids and 

 salts without discovering any exception to the generalized expres- 

 sion given by him. 



On the Constitution of Atropine, by Prof I.adenburg. — This 

 body is shown to belong to the class of bodies known as alkines. 

 The reactions of tropine and its transformations show that it 

 stands in a direct and simple relation to atropine. It has not 

 yet been pDSsible, however, to synthesize tropine. 



The Reduction-products oj the JVitro-paraJins and Alkyl 

 Nitrites,hy Vrof. DunstanandT. S. Dymond. — The authors have 

 studied the reduction of ethyl nitrite, using ferrous hydroxide as the 

 reducing agent. More than two-thirds of the nitrogen of the ethyl 

 nitrite is liberated in the form of gas, either nitrous oxide or nitro- 

 gen ; the remainder appears partly as ammonia and partly as ethyl- 

 amine. If potassium hydroxide is mixed with the ferrous com- 

 pound a considerable quantity of potassium hyponitrite is formed. 

 It is also probable that ethyl hyponitrite, a compound that has 

 not yet been prepared, may also be formed as an intermediate 

 compound. The authors are further investigating the change 

 with the object of isolating this compound and of discovering 

 the mode of formation of the ethylamine. The reducing action 

 of ferrous hydroxide on the nitro-paraffins was also partially 

 investigated with interesting results. 



On a Partial Separation of the Constituents of a Solution 

 during Expansion by Rise of Temperature, by J. W. Mallet, 

 F. R. S. — When solutions of colloid substances — some alcoholic, 

 some aqueous — are exposed to cold, and afterwards to a gradu- 

 ally increasing temperature, the expansion in the liquid has been 

 noticed to take place with a partial or entire separation of the 

 substance dissolved in the upper layer, without any deposition 

 of solid matter. 



A New Method for Determining Micro- Organisms in Air, by 

 Prof Carnelley and Thos. Wilson, University College, Dundee. 

 — This is a modification of Hesse's well-known process. It 

 consists essentially in the sub-titutian of a flat-bottomed conical 

 flask for a Hesse's tube. Its chief advantages are : (i) much 

 smaller cost of flask and fittings as compared with Hesse's 

 tubes ; (2) very much fewer breakages during sterilization ; 

 (3) ?.J^^\ economy in jelly ; (4) freedom from leakage during 

 sterilization ; (5) results not ^^tiated by aerial currents. 



The Absorption-Spectra of Rare Earths, by Dr. G. H. Bailey. 

 — This paper is an examination of the conditions of observation 

 of absorption-spectra with a special view to the recent announce- 

 ment of the twenty new tlements of Kriiss and Nilson. The 

 author finds that the strengths of the absorption-bands do not 

 diminish equally in all parts of the spectrum when the liquid is 

 diluted. The presence of nitric acid also effects not only a dis- 

 placement of the bands, but also an alteration in their relative 

 intensity. It is further pointed out that a record of the strength 

 of the bands in mixtures containing, in some cases, large quan- 

 tities of samaria and erbia, and in others none, cannot be used 

 as a means of comparison, and deductions drawn from variations 

 of intensity are untrustworthy. Whilst acknowledging that, 

 with due allowance for such factors, some assistance may be 

 gained towards the course of fractionation, the author considers 



the announcement of new elements quite premature, and only 

 calculated to throw further confusion into this already difficult 

 field of work. 



The Absorption- Spectra of the Haloid Salts of Didymium, by 

 Dr. G_. H. Bailey.— Bunsen has described certain variations that 

 occur in the absorption-spectra given by crystals of the didymium 

 salts. In this paper are detailed the variations produced' in the 

 absorption-spectra of crystalline salts of didymium when exa- 

 mined in polarized light. A comparison of the chloride, brom- 

 ide, and iodide of didymium has also been made, from which 

 it appears that in the bromide the bands are situated 5\ further 

 towards the red end of the spectrum than in the chloride, whilst 

 the displacement for the iodide is I4\ towards the violet. In 

 the solution of the chloride (or nitrate) the bands have almost 

 the same position as in the crystals of the iodide, whilst the 

 addition of nitric acid causes a displacement of I2,\ towards the 

 red. It is proposed to determine how far this displacement of 

 bands is due to the dispersion equivalent of the menstruum, and 

 whether it gives evidence of dissociation in the liquid. 



On Solution, by W. Durham. — The theory of .solution adopted 

 by the author of this paper was published by him before the 

 koyal Society of Edinburgh in 1878. According to these views 

 solution is due to the chemical affinity of the elements of the 

 substance dissolved for the elements of the solvent. 



Thermal Phenomena of Neutralization, and their bearing on 

 the Nature of Solution, by W. W. J. Nicol. — A consideration of 

 the general relationship exi -ting between the heats of formation of 

 various salts in dilute aqueous solutions. 



Notes on some peculiar Voltaic Combinations, by C. R. A. 

 Wright, F.R.S., and C. Thompson. — The combinations consist 

 of a class of cells in which one or both of the "plates" is a 

 film of gas condensed on the surface of an electrically conducting 

 solid, which is itself not appreciably acted on. In Grove's gas 

 battery both plates are gas films. Mercury and silver in dilute 

 sulphuric acid opposed to aeration plates of platinum sponge 

 form sulphates, whilst gold dissolves in potassium cyanide under 

 the same conditions. If an acid and alkaline solution be united 

 by means of a wick a considerable current is producible for a 

 short time in the external circuit but this falls off rapidly in 

 consequence of the development of fre>; hydrogen on the surface 

 of the plate in the acid fluid and of oxygen on the other plate. 

 No direct quantitative proof of this has, however, been given, 

 and there are given in this paper a number of experiments show- 

 ing that for every milligram aie equivalent of silver deposited 

 1 1 '2 cc. of hydrogen are evolved. 



The Present Aspect of the Question of the Sources of Nitrogen 

 in Vegetation, by Sir J. Lawes, F.R.S., and Dr. Gilbert, F. R.S. 

 — An outline of the work of various experimenters in this line 

 of research was given, indicating that, whereas in accordance with 

 the original observations of Boussingault the authors had found 

 that nitrogen was assimilated in part from the atmosphere 

 direc ly, the results of Berthelot, Frank, and others derived all 

 nitrogen from the soil. These results were criticised, and it was 

 pointed out that the methods pursued failed in that they did not 

 rep.-esent normal conditions of growth of vegetation. 



Dispersion Eqicivalen.'s and Constitutional Foi-mula:, by Dr. 

 J. H. Gladstone. — The difference between the refraction equiva- 

 lent, as observed for the line " A " and for the line " H " in the 

 spectrum, is called the dispersion equivalent. The refraction 

 equivalent of a compou.ul is in general the sum of the refraction 

 equivalents of the elements of which it is composed, but varies 

 according to the constitution. The same holds for the dispersion 

 equivalent, and it is shown that in some cases differences are 

 observable in this respect where they are not indicated by con- 

 stitutional formulae, as, for instance, in the allyl compounds, and^ 

 in naphthalene deriva'ives. 



On Organic Vanadates, by J. A. Hall. — A series of organil 

 vanadates are described, which can be distilled under reduce' 

 pressure without decomposition. They are obtained by the action 

 of an alkyl bromide on silver orthovanadate. 



On some Neiu Cinnxmic Acids, by Dr. Cohen and Pro^ 

 Perkin. — A description of a method of obtaining certain sub 

 stituted cinnamic acids from aromatic aldehydes in cases where 

 from the nature of the aldehyde, Perkin's reaction cannot be em? 

 ployed. The aldehydo-salicylic acids are converted into ethereal 

 salts, and these are heated with sodium alcoholate, and finally 

 with sodium acetate and acetic anhydride. 



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