72 



NATURE 



[May 2 1, 1891 



+ 3H2O, is obtained by adding a slight excess of ammonia to a 

 solution of ferric chloride containing an excess of dextrose ; on 

 standing, a deep red solution is obtained, which when poured into 

 •90 per cent, alcohol yields the dextrosate of iron as a red 

 flocculent precipitate. The moist compound dissolves easily in 

 water to a red solution, is decomposed on boiling, but is not 

 decomposed by ammonia, potassic ferrocyanide, or potassic 

 thiocyanate. The dry compound is insoluble in water. — A 

 rapid method of estimating nitrates in potable waters, by Dr. G. 

 Harrow. The method depends on the reduction of nitric to 

 nitrous acid by means of zinc dust and hydrochloric acid, in a 

 very dilute solution, in the presence of o-naphthylamine and 

 sulphuric acid ; the estimation is made by comparing the depths 

 of the pink azo-coloration developed in the solution with that 

 arising on similar treatment of standard nitrate solutions. 

 When nitrites are present, the amount is estimated in a similar 

 manner prior to the addition of zinc dust, and due allowance 

 is subsequently made. A number of comparisons with the 

 Crum method show that very satisfactory results are obtainable. 

 — The "gravivoiumeter," an instrument by means of which the 

 observed volume of a single gas gives directly the weight of the 

 gas: a preliminary note, by F. R. Japp, F.R. S. The author 

 describes a method of constructing a gas apparatus, by means of 

 which, with an ordinary graduation in cubic centimetres, any 

 required single gas may, without observation of temperature or 

 pressure and without calculation, be measured under such con- 

 ditions that each cubic centimetre represents a milligram of the 

 gas. The author describes the apparatus in detail and the 

 method of using it, and he anticipates that it will, at least, give 

 results sufficiently accurate for technical purposes. — Mr. de 

 Mosenthal exhibited one of Lipmann's coloured photographic 

 negatives. — The action of acetic acid on phenylthiocarbimide, by 

 J. C. Cain and Dr. J. B. Cohen, Owens College. The authors 

 show that the product of the action of pure glacial acetic acid on 

 phenylthiocarbimide is not diacetanilide, as stated by Hofmann ; 

 but that two compounds are formed — namely, diphenylurea and 

 acetanilide. At low temperatures diphenylurea is mainly formed, 

 at higher temperatures acetanilide. The reactions may be ex- 

 pressed by the following equations : — 



2C6H5NCS + 6C2H4O2 

 and 



(C6H5NH)2CO + 3(C2H30)j.O 



•2H2S + CO2 



(C6H5NH)2CO + 2C2H402 = aCgHgNHa + iCaHsO^O-l- COg. 



— The action of aluminium chloride on benzenoid acid chlorides, 

 by R. E. Hughes, Jesus College, Oxford. The author has ex- 

 . amined the action of aluminium chloride on cinnamic and 

 liydrocinnamic chlorides, in the expectation that pentamethylene 

 derivatives might result. The experiments, however, afforded 

 negative results. The chloride was either dissolved in or mixed 

 with light petroleum, and aluminium chloride then added ; action 

 set in at 80-90° in the case of cinnamic,and at 50° and more briskly 

 in the case of hydrocinnamic, chloride. The chief product in both 

 cases was an ill-characterized substance, which has not been ex- 

 amined. The author also describes the following compounds : 

 hydrocinnamic chloride, hydrocinnamide, and hydrocinnam- 

 anilide. It is noted that benzoic and cinnamic acids may be 

 •readily separated by treating the mixture with phosphorus 

 pentachloride and distilling the product under reduced pressure ; 

 the portion passing over below 95° under 10 mm. contains the 

 benzoic chloride. 



Paris. 

 Academy of Sciences, May 11.— M. Duchartre in the 

 -chair. — Essay on graphical dynamics, with reference to the 

 periods of motion of hydraulic motors, by M. H. Leaute.— On 

 the. lowering of the surface of water in a horizontal cylindrical 

 vessel, by M. Haton de la Goupilliere.— On the boundaries of 

 the littoral zones, by M. Leon Vaillant. — Observations made at 

 Marseilles Observatory of the asteroid ^os) discovered on March 

 31, by M. Borrelly. The observations for position extend from 

 April 6 to April 30.— Elements of the orbit of Borrelly's new 

 asteroid (sm), by M. Fabry.— Provisionary elements of Borrelly's 

 asteroid deduced from observations made at Marseilles Observa- 

 tory on March 30, April 8, 18, and 26, by M. Esmiol.— Solar 

 observations made at the Royal Observatory of the Roman 

 College during the first quarter of 1891, by M. Tacchini. 

 —On the movement of the moon's perigee, by M. Perchot. 

 —On limited permutations, by M. C. A. Laisant.— On a class 



NO. I 125, VOL. 44] 



of complex numbers, by M. MarkofF. — On a registering mano- 

 meter applicable to pieces of ordnance, by M. P. Vieille. — 

 An "elastic" theory of plasticity and fragility of solid bodies, 

 by M. Marcel Brillouin. — On the wave-surface in crystals, by 

 M. C. Raveau. — On the determination of the dielectric constant 

 of glass by means of very rapid electrical oscillations, by M. R. 

 Blondlot. The author has made some experiments which sup- 

 port Prof. J. J. Thomson's conclusion that the specific inductive 

 capacity of glass is very nearly equal to the square of the index 

 of refraction, and has least value when a slow frequency of 

 vibration is employed. — On a new compound of oxygen and 

 tungsten, by M. E. Pechard. — Thermic study of bibasic organic 

 acids with simple functions, by M. G. Massol. — Remark on the 

 preceding note, by M. Berthelot. — On the fourth primary amyl- 

 alcohol, by M. L. Tissier. — On the diffusion of fresh water into 

 sea-water, by M. J. Thoulet.— On the theory of M. Tschermak's 

 felspars, by M. K. de Kroustchoff. A description is given of a 

 new triclinic felspar having a composition very similar to oligo- 

 clase, but distinguished from it by several peculiarities. — On the 

 genital organs of some Tristomidae, by M. G. Saint-Remy. — On 

 the constitution of the sexual nuclei of plants, by M. Leon 

 Guignard. — On the groups of the genus Clusia, by M. J. Vesque. 

 — The parasitic fungus of the larva of the cockchafer, by MM. 

 Prillieux and Delacroix. — The parasite of the cockchafer, byM. 

 Le Moult. — On a remarkable inversion of strata termed pli 

 couche observed near Toulon, by MM. Marcel Bertrand and 

 Zurcher. — On the permanence of the orogenic effort in the 

 Pyrenees during the geological periods, by M. Roussel. 



Amsterdam. 

 Royal Acadeniy of Sciences, April 24.— Prof, van de 

 Sande Bakhuyzen in the chair. — Mr. van der Waals dealt with 

 a formula for electrolytic dissociation, which may be deduced 

 from his theory of a mixture. This formula accounts for the 

 facts (i) that ions may combine with absorption of heat; 

 (2) that the parameter of electrolytic dissociation varies with the 

 medium which holds the salt-molecules in solution ; (3) that 

 the quantity of free ions may diminish when the quantity of 

 salt-molecules increases. 



CONTENTS. PAGE 



Pycnogonids. By E. P. W 49 



A Text-book of Chemistry based on the Periodic 



System 50 



Our Book Shelf:— 



Roberts : " Eighteen Years of University Extension" . 52 

 Hepworth : "Evening Work for Amateur Photo- 

 graphers " • 52 



Letters to the Editor : — 



The University of London Question.— W. T. Thisel- 



ton Dyer, C.M.G., F.R.S. ; F. Victor Dickins 52 



Co-adaptation. — Prof. George J. Romanes, F.R.S. 55 



A priori Reasoning. — Prof. George Henslow ... 55 

 The Natural Selection of Indian Corn. — T. D. A. 



Cockerell 56 



The Soaring of Birds. {With Diagrams.)— S. E. 



Peal 56 



On some Points in the Early History of Astronomy. 



III. {Illustrated.) By J. Norman Lockyer, F.R.S. . 57 



Forestry in North America. By Prof. W. K. Fisher 60 



Daily International Weather Charts 62 



Joseph Leidy, M.D 63 



The Science Museum 63 



Notes 65 



Our Astronomical Column: — 



The Photography of Faint Nebula 69 



Variations in Latitude 69 



Re-discovery of Wolf's Comet (1884 III.) 69 



The Paris Observatory. By W. J. L 70 



Notes on the Physiological Action of Carbon- 

 Monoxide of Nickel. By Prof. John G. McKen- 



drick, F.R.S., and William Snodgrass 70 



Societies and Academies 71 



