470 



NATURE 



\_Sept. 15, 1 88 1 



compound could be used in lecture experimeuts. For instance, 

 it may be used to show the conduction of heat along a copper 

 rod ; for this purpose the rod is cuated with the red compound, 

 which is gradually blackened as the heat travels along the rod. 

 It miy al-o be substituted for wax in Tyndall's experiment for 

 showing how crystals conduct heat. There are also a variety of 

 other ways in which it may be applied. 



The Effect of the Spectrum on Silver- ChloriJe, by Capt. Abney, 

 R.E., F.R.S. 



Alterations in the Properties of Nitric Ferments by Cultivation, 

 by R. Warington. — The author, after giving an account of his 

 experiments on the cultivation of these ferments, which con ist 

 of organisms resembling bacteria, state? that these nitrifying 

 ferments are capable of existing in three forms — (i) the nitric 

 ferment of soil, which converts both ammonium salts and nitrites 

 into nitrates ; (2) the altered ferment, which c inverts ammonium 

 salts into nitrites, but fails to convert nitrites into nitrates ; (3) a 

 surface organism which converts nitrites into ititrates. 



On tlte Fluid Density of Certain Metals, by Prof. W. Chandler 

 Roberts, F.R.S., and T. Wrightson, C.E.— This is an account 

 of a continuation of experiments upon this subject, some of 

 which were submitted to the Section at Swansea (vide Nature, 

 vol. xxii. p. 44S). The authors also exhibited the oncosimeler 

 described in the Journal of the Iron and Steel Institute (ii. 1879, 

 p. 418), by the aid of which these results were obtained. The 

 following table contains the results obt uued : — 



On Molecular Attraction, by F. D. Brown, B.Sc- — The author 

 points out that, if we regird chemical affinity as neutralised by 

 the union of two elements, we are then unable to account for the 

 reactions taking place between m^Iecale.s, and involving an in- 

 teraction of the atoms composing different molecules. If, how- 

 ever, the act of combination be regarded as producing no 

 change in the chemical forces, and it be suppo.ed that the same 

 attraction is exerted between any given pair of atoms without 

 regard to the state of combinati jn of one or both of the atoms, 

 then a reasonable account can be given of chemical reactions, and 

 the existence of m decular combinations does not appear very 

 remarl.able. Further, we are provided wiih a more or less 

 effective explanation of the relative volatility of substances. 

 Reasoning from this point of view, and considering the carbon 

 compounds specially, the author concludes that intermolecular 

 attraction should be greater in an acid than in a corresponding 

 alcohol ; greater in an alcohjl of high mjlecular weight than in 

 a homologue of which the molecule i? les; complex ; greater in 

 a primary alcohol than in the secondary or tertiary isomeride ; 

 and finally, greater in a chlorinated compound than in the corre- 

 sponding substance containing hydrogen. If the volatility of a 

 substance be a measure of the forces of attraction between the 

 molecules, then it must be admitted that the boiling points of 

 organic compounds show with some reason that the abjve ex- 

 pression represents the value of intermolecular attraction. From 

 this point of view the study of the latent heat of many carbon 

 compounds would materially aid us in the solution of the pro 

 blem of chemical affinity. 



On the Relative Atomic Weights of Silver, Manganese, and 

 Oxygen, by Prof. Dewar, M.A., F.R.S., and A. Scott, B.A., 

 B.Sc. The authors have determined the atomic weight of 

 manganese, in relation to silver and oxygen, by a complete 

 a:ialysi' of silver permanganate. Taking the atomic weight of 

 silver to be 108, that of oxygen to be 16, the following values 

 have been obtained for the atomic weight of manganese, 55 '51, 

 54-04, 54-45. The ~e numbers do not agree very well amongst 

 themselves, nor with the nujibers obtained from the analysis of 

 pure manganese peroxide, made from manganese nitrate. By 

 this latter method the following values were obtained, viz., 

 Mn = 53-6 and 53-3. 



Note on the Phosphates of Lime an I Ammonia, by J. Alfred 

 Wanklyu. — When ammonia is added to a joluble calcic phos- 

 phate a precipitate is ob'ained, which dissolves on heating, 

 forming a vi-cid solution which solidifies oa cooling. The 

 soluble salt formed the author regards as having the composition 



P.,05CaO(NH4)20H20. The author confirms Morfit's observa- 

 tion, that bjne earth dissolved in acid is reprecipitated by 

 alkalies in the form of a hydrated tribasic phosphate ; a fact 

 which he considers of great importance to agriculture. 



On the Separation of Hydrocarbon Oil from Fat Oils, by A. H. 

 Allen, F.C.S. — The author pointed out that the exten-ive pro- 

 duction of hydrocarbon oils and their cheapness had led to their 

 being employed for the purpose of adulterating animal and 

 vegetable oils. Indications of their presence are afforded by 

 the determination of the density of the oil, by the lowering of its 

 flashing p >int and boiling point, further by its taste and the 

 odour produced on heating. An oil so adulterated is not com- 

 pletely saponified, and the hydrocarbon oil may be removed 

 from the product of saponification by extraction with ether. 

 Fluorescence i". also to some exte it a useful indication of the 

 presence of such a mineral oil ; the fluorescence of some mineral 

 oils may, however, be destroyed by chemical means, and as some 

 mineral oils are not fluorescent the absence of fluorescence in an 

 oil does not therefore indicate the absence of a mineral oil. 



On Bo-wkett's N'eiu Thermograph, by W. Lant Carpenter, 

 B.A., B.Sc, F.C.S. — This is an instrument for recording changes 

 of temperature, which are measured by the action of heat upon a 

 hollow circular metallic ring connected with a circular vessel, 

 the whole being filled with fluid and hermetically sealed. One 

 end of the ring is fixed, the other is free to move, aid its motion 

 is magnified by a series of levers, to the end of u hich is attached 

 a recording pen. Increments of heat cause increuients of pressure 

 in the ring, which moves at its free end. The instrument has 

 hitherto been used for clinical purposes only, but the author 

 thinks it might with advantage be u-ed in chemical and physical 

 researches. 



The Blowing Wells near Northallerton, by T. Fai'ley, 

 F.R.S.E. — The author gave an account of a .series of observa- 

 tions on these wells, of which there are three in the neighbour- 

 hood of Northallerton. The gas issuing from the fi-sures in 

 these wells has been analysed, and is apparently nothing more 

 than common air. 



On the New Metal Actinium, by J. L. Phipson. — The author 

 stated that he had been able to separate a new element from the 

 pigment zinc-white. The oxide of the new element is said to 

 be slightly soluble in causlic soda, and is soluble in ammonia 

 and ammoniacal salts- Its colour i- uninfluenced by exposure to 

 light. The sulphide of actinium is described as a pale yellow 

 canary -c dcured substance ; it is insoluble in ammonium sulphiiie, 

 is soluble in acetic acid, and becomes darker on exposure to the 

 air. 



On some Vapour- Density Determinations, by Prof. Dewar, 

 M.A., F.R.S., and A. Scott, B.A., B.Sc— The authors de- 

 scribed the apparatus they employed for the determination of 

 the vapoar-densities at hi^h temperatures, and the means 

 adopted for examining the vapours to ascertain whether or not 

 decomposition had taken place. The vapour-densities of the 

 halogen compounds of several metals have been determined, and 

 it is interesting to note that the authors find, according to its 

 vapour-den-ity, the molecular formula for ferrous chloride is 

 FeClo. 



Some Remirks on Crystallogeny, by Prof J. P. Cooke 

 (Harvard University, U.S.A.). 



On a Ne-iO System of Blow-pipe Analysis, by Lieut.-Col. Ross. 

 — The author described his system of blow-pipe analysis, and 

 exhibited a compact form of blow-pipe aud other necessary 

 apparatus for use when travelling. 



On Experiments with Manures on Barley Crops, Season 18S1, 

 by Ivison Macadam, F.C.S.— The author gave a detailed 

 account of his experiments on two fields sown with barley in 

 April of this year. The previous rotation of crops was as 

 follows:— in 1878 potatoes with 20 tons of farmyard manure per 

 acre, and 4 to 5 cwt. of dissolved manure ; in 1879 wheat, no 

 manure; in iSSo turnips, 20 tons per acre of town ashes and 

 5 to 6 cwt. of dissolved manure. The only difference between 

 the two fields was that in one case the turnips were carted away, 

 whilst in the other they were eaten on the ground by sheep. 

 From the time when the birley appeared to the time of cutting, 

 determinations of the following points were made every week : 

 (I) the weight of the plant; (2) length of straw; (3) rate of 

 storage of saline matter by the plant ; (4) amount of water, 

 nitrogen (given as ammonia), organic and vegetal matter ; (5) 

 the amount of the various saline ingredients present in the ash. 

 The results appear to show that, in the ca e of the field where 

 the turnips had been eaten on the ground, the barley crop grew 

 more rapidly and was more healthy than that on the other field. 



