April 12, 1877] 



NATURE 



'^21 



charge, benzene absorbs about two atoms of hydrogen, yielding 

 a polymeride of CgHg, a resinous substance with an irritating 

 smell. On heating, benzene first distils over ; then a liquid, 

 soluble in strong nitric and sulphuric acid, finally leaving carbon 

 containing a little hydrogen. Oil of turpentine absorbs about 

 2*5 atoms of hydrogen, yielding resinous products. Pure carbon 

 does not combine with hydrogen under the influence of the 

 discharge, and a mixture of hydrogen with acetylene behaves 

 much in the same way as pure acetylene. A mixture of hydro- 

 gen and carbon monoxide yields the solid body observed by 

 Brodie and Thenard, 5CO + 3H2 = COj + C^\0^, a trace of 

 acetylene being formed. 



Phosphorus Pentafluoride. — Professor Thorpe has 

 lately described this body (Liebig, Ann. clxxxii.), which he 

 prepares by the gradual addition of phosphorus pentachloride to 

 arsenic trifluoride. Phosphorus pentafluoride is a colourless gas, 

 with a pungent and extremely irritating odour ; it reacts upon 

 water, forming phosphoric and hydrofluoric acids. The density 

 with regard to hydrogen was found to be 63*23 (theory requiring 

 63) ; under the pressure of twelve atmospheres at 7* it exhibits 

 no marked deviation from Boyle's law ; it does not seem to be 

 affected by the passage through it of electric sparks either when 

 pure or when mixed with hydrogen or oxygen. With dry 

 ammonia it forms the compound 2PF55(NH3). 



Molecular Volumes of Sulwiates and Selenates.— 

 An account of investigations on this subject has lately been pub- 

 lished by Otto Petterson {^Dmt. chem. Ges. Ber., ix. 1559), in 

 which he finds that, in the series of sulphates and selenates of 

 potassium, ammonium, rhubidium, and caesium the molecular 

 volume of the compound is regularly increased by 6 "6 when the 

 group SO4 is exchanged for the group Se04 ; also, that the sub- 

 stitution of a molecule of ammonium, rubidium, or c?esium for 

 a molecule of potassium produces an increase in volume of 9, 8, 

 and 23 respectively in the selenates as well as in the sulphates. 

 He has also examined the double sulphates and selenates of 

 cobaU, nickel, and copper with potassium, in which results are 

 found tending to confirm the hypothesis that in double salts the 

 components are unaltered ; this is more marked in the case of 

 the selenates, in which the volumes of the double salts are equal 

 to the sums of the volumes of their components. The author 

 disagrees with Favre and Valson in their conclusions that double 

 salts cannot exist in solution, and are formed at the moment of 

 crystallisation ; he believes on the contrary that as no contraction 

 takes place on crystallisaliou these salts may be held to exist in 

 the same condition in solution as after crystallisation ; the double 

 salt of thallium is, however, an exception. In the case of the 

 alums also when obtained in an anhydrous condition the volume 

 of the salt exactly equals the volumes of its components. 



Contributions to the Theory of Luminous Flames. — 

 A continuation of experiments on the above subject is given by 

 K. Heumann {Liebig' s Ann., clxxxiii.), in which he finds that 

 carbonaceous matter will give luminous or non-luminous flames, 

 according as the temperature of the flame is high or low ; di- 

 luting the gaseous combustible with indifferent gases also requires 

 a higher temperature to cause a separation of the carbon, and 

 thus produce luminosity. Reduction of temperature in a flame 

 prevents either partially or entirely the formation of carbon, 

 consequently the author thinks that the deposition of carbon on 

 cold surfaces in a flame is not the consequence of cooling, as a 

 deposition may be formed on red-hot surfaces, but burns away 

 in contact with air. In burners of different materials, those of 

 iron were found to prevent the luminosity of the lower part of 

 the flame to a greater extent than those of 'steatite, also when 

 the burner is heated, a greater amount of light is produced, the 

 consumption of the combustible remaining the same. Ilerr 

 Heumann thinks that by heating the burner the luminosity is 

 increased, and extends to a greater extent over the lower part of 

 the flame. 



NOTES 



We are informed that H.M. Government has just been 

 pleased to sanction the necessary expenditure to replace the 

 important deep-soil thermometers of the Royal Observatory, 

 Edinburgh, which were so cruelly broken by a madman last 

 September. The estimate has been prepared by Messrs. Adie 

 and Son, Princes Street, Edinburgh, and is understood to 

 include everything that can conduce to scientific accuracy. 



Prof, J. Dewar, F.R.S.E., Jacksonian Professor of Natural 

 Experimental Philosophy in the University of Cambridge, has 

 been elected Fullerian Professor of Chemistry to the Royal 

 Institution in the room of Dr. Gladstone, resigned. 



Dr. Col an, the senior medical officer of the recent Arctic 

 Expedition, has been promoted to be Deputy Inspector-General 

 of Hospitals. 



Dr. W. B. Carpenter, C.B., commenced, on Monday 

 evening, at the School of Mines, Jermyn Street, a free course of 

 lectures on geology, which he is delivering as Swiney Professor. 



At the meeting of the French Geographical Society on April 4 

 it was announced that the great gold medal of the Society had been 

 awarded to Commander Cameron in recognition of his services 

 in the cause of geographical science. 



The estimate for " Education, science, and art in Great 

 Britain amounted in 1853-4 to 578,000/. ; this year the estimate 

 was 3,546,000/," "In 1835 the Government paid for public 

 education a sum of 26,750/., but in 1875-6 the amount had 

 increased to 3,972,008/." 



Among the fifty-seven candidates for admission into the Royal 

 Society are two clergymen of the Church of England, one 

 Wesleyan minister, one peer, one foreign baron, one baronet, 

 eleven M.D.s, &c. 



The late Mr. J. C, Tufnell has bequeathed to University 

 College, Gower Street, 5,000/, to be used in establishing two 

 scholarships, one in general chemistry and the other in analytical 

 and practical chemistry. 



The Rev. E. Ledger, Gresham Professor of Astronomy, will 

 deliver a course of Lectures on the Telescope, m the theatre of 

 Gresham College, on the evenings of April 17, 18, 19, 20. The 

 electric light will be used to illustrate the lectures. 



Liebig is to have another monument. A few weeks ago we 

 noted the "inauguration" of one at Darmstadt. Subscriptions 

 are now being collected for the purpose of raising a statue to 

 him in Munich, About 7,000/. has already been contributed, 



Mr. PI, W. S. Worsley-Benison, F.L.S., has been ap- 

 pointed I^ecturer on Botany at Westminster Hospital. 



The services of Mr, W. Saville Kent, F,L,S,, F,Z.S,, have 

 been engaged temporarily to superintend and place in thorough 

 order the "Fish House" at the Zoological Society's Gardens, 

 Regent's Park. A considerable number of marine fish and other 

 specimens of interest have been imported to the tanks during the 

 past week. 



Two views have been offered as to the mode of action of the 

 gas in the radiometer. One attributes the motion to reaction of 

 gas particles getting heated on the vanes, then dancing off; the 

 other to air currents which are directed towards the plate in con- 

 sequence of heated air rising from it. M. Neesen has endea- 

 voured {Fogg. Ann.) to decide between these views. If the second 

 view is correct, he argued, the wall of the vessel, by becoming 

 also heated, must also acquire influence through rise of heated 

 air from it as from the vanes. If the rotation be merely a phe- 

 nomenon of reaction there is no reason to suppose such an influ- 

 ence of the fixed wall. Now by giving the radiometer an 



