December 21, 1905] 



NA TURE 



189 



The critical pressure is calculated to be 296 atmospheres, 

 and the critical density 049. 



The value abs. critical temperature 



iS-g ; this 



critical pressure 

 proportional to the volume of the molecule, and is equal 

 to 5-1 times the corresponding number for carbon monoxide 

 (3-7). The molecular volume of iron carbonyl at its boil- 

 ing point is 150, so that, taking 7-0 as the volume of the 

 iron atom, 28-6 is the volume of each carbon monoxide 

 group. The molecular volume of carbon monoxide at its 

 boiling point is 35, therefore a greater contraction would 

 occur in the formation of iron carbonyl from liquid carbon 

 monoxide and iron than in the formation of nickel carbonyl 

 under similar conditions. 



Vapour density determinations by V. Meyer's method in 

 carbon monoxide, nitrogen, and hydrogen at different 

 temperatures show the effect of increase of temperature 

 and the rapid diffusion of hydrogen in increasing, and of 

 carbon monoxide in diminishing, the dissociation. 



The chemical reactions of iron carbonyl are very similar 

 to those of nickel carbonyl, but its stability is greater. 

 Chlorine, bromine, iodine, their compounds with one 

 another and their hvdrides react with iron carbonvl 

 giving ferrous salts and carbon monoxide ; the reaction 

 with bromine takes place more slowly than that between 

 iodine and nickel carbonyl. Neither sulphur nor nitric 

 oxide reacts with iron carbonyl, whereas both react readily 

 with nickel carbonyl. Sulphuric acid, on the other hand, 

 decomposes iron carbonyl more readily than it does nickel 

 carbonyl. 



Benzene in presence of aluminium chloride reacts with 

 iron carbonyl, with cold to give benzaldehyde, and at 

 100° C. to give anthracene, exactly as with nickel carbonyl. 



Iron pentacarbonyl alone or in solution in ordinary 

 organic solvents is decomposed bv sunlight according to 

 the following equation, 2Fe(CO) 5 = Fe 2 (CO), + CO. The 

 second compound of iron and carbon monoxide is de- 

 posited as an orange, crystalline solid from most solvents, 

 but is retained in solution by pyridine. The reaction takes 

 place rapidly under pressures of carbon monoxide up to 

 150 atmospheres, and yet is very slowly reversed in the 

 dark under small pressures of carbon monoxide. This 

 decomposition takes place slowly at the temperature of 

 liquid air, but if the iron pentacarbonyl or its solutions 

 be heated to any temperature above 6o° C, then no solid 

 is deposited and no decomposition occurs. Solutions of 

 iron carbonyl in nickel carbonyl at the ordinary tempera- 

 ture undergo no decomposition and no solid is formed 

 unless the solution contains more than 30 per cent, of 

 the iron carbonyl, when some solid is formed. These 

 solutions are of a much lighter colour than solutions of 

 equal concentration in other solvents, and it is suggested 

 that the two carbonyls may unite to form a compound 

 which is unaffected by light. 



The solid iron carbonyl forms lustrous hexagonal plates 

 having a specific gravity of 2085 ; its molecular volume is 

 therefore 174. 



The solid iron carbonyl when heated alone decomposes 

 at ioo° C. into carbon monoxide, liquid iron carbonyl, 

 which is coloured green, and iron ; when heated with 

 carbon monoxide under pressure it is completely converted 

 into liquid iron pentacarbonyl. 



If the solid iron carbonyl be heated with a solvent such 

 as ether or toluene, a solution of an intense green colour 

 is produced ; this green solution on exposure to light de- 

 posits the yellow, crystalline, solid carbonyl again. The 

 change from solid to green solution and back again can 

 be repeated indefinitely by the action of heat and light 

 alternately. 



Zoological Society, November 28. — Dr. Henry Woodward, 

 F.R.S., vice-president, in the chair. — Exhibitions. — Photo- 

 graphs of a horse bearing incipient horns : J. T. 

 Cunning-ham. The horns were about |-inch in length, 

 the left being slightly larger than the right, and there 

 could be no doubt that they were outgrowths of the frontal 

 bone. The growths were covered with normal skin and 

 hair. — Photographs, taken in the Horniman Museum 

 al Forest Hill, of a sea-anemone (Anemonia sulcata) in 

 thi process of division: F. Slade. — A living albino speci- 



NO. 1886, VOL. 73] 



men of the field-vole (Microtus agrestis) captured last July 

 in Wales : D. English. — A living lizard, Hacerta muralis, 

 from Brozzi, province Florence, received from Dr. A. 

 Banchi : G. A. Boulenger, F.R.S. The lizard belonged 

 to the typical form of the wall-lizard, but was remarkable 

 for its black coloration above and below. Melanistic forms 

 of the wall-lizard were well known on small islands in the 

 Mediterranean, but, so far as Mr. Boulenger was aware, 

 no black specimen had ever been recorded from the main- 

 land. The scales across the body numbered fifty-eight, and 

 the lamellar scales under the fourth toe twenty-five in the 

 specimen exhibited, these two numbers being sufficient to 

 distinguish the Brozzi lizard from the melanotic insulars 

 previously described. — A living specimen of the violet- 

 cheeked humming-bird [Petasophoya iolota) brought from 

 Venezuela and presented to the society's menagerie : 

 Captain A. Pam. A general account of the habits of 

 these birds, as observed by Captain Pam, in a wild and 

 captive state, and notes on their management and feeding 

 while in confinement. — A named set of the birds collected 

 in Japan by Mr. M. P. Anderson in connection with the 

 Duke of Bedford's exploration in eastern Asia: W. R. 

 Ogiivie-Grant. No new species were obtained, but several 

 of the specimens were of special interest as illustrating 

 stages of plumage not represented in the British Museum. 

 — Papers. — A transition in the general type of colouring 

 from the wholly black Colobus guereza in one direction, 

 through several intermediate forms, towards the black and 

 white C. caudatus, and in another direction towards 

 C. vellerosus : R. Lydekker. — A mounted specimen of the 

 white-maned serow (Xcnwrhaedus argyrochaetes, Heude), 

 of Szechuen, the first example of the species ever received 

 in England, and perhaps in Europe : R. Lydekker. — 

 Mammals collected in Japan by Mr. M. P. Anderson for 

 the Duke of Bedford, and presented by the latter to the 

 National Museum : O. Thomas. The collection was one 

 of the most valuable for scientific purposes which had ever 

 been received from any one region. More than 600 specimens 

 had been obtained, belonging to 50 species and subspecies, 

 of which several were described as new. — A revision of the 

 fishes of the family Galaxiidse : C. T. Regan. Two genera 

 were recognised, Galaxias and Neochanna, the latter consist- 

 ing of a single species only. Twenty-eight species of Galaxias 

 were described, including G. attcnuatus, Jenyns, found on 

 the coasts and in the rivers of Australia, New Zealand and 

 Chili, Patagonia, and the Falkland Islands, and two 

 peculiar to the Cape of Good Hope, five to New Zealand 

 and the neighbouring islands, five to Chili, Patagonia, and 

 the Falkland Islands, and fifteen to Australia and 

 Tasmania. Five species were described as new to science. 

 — The mammalian fauna of China. First paper : J. L. 

 Bonhote. The present part dealt with the Murina?, con- 

 taining the genera Mus and Micromys, giving descriptions 

 and synonymy, as well as emphasising the distinctive 

 characters by which the various species might be easily 

 distinguished. — Some additions to the knowledge of the 

 anatomy, principally of the vascular system, of Hatteria, 

 Crocodilus, and certain Lacertilia : F. E. Beddard. — 

 Descriptions of 1 1 1 new species of phytophagous Coleoptera 

 of the family Halticida; : M. Jacoby. 



Chemical Society, December 7. — Prof. R. Meldola, 

 F.R.S., president, in the chair. — The constitution of 

 nitrites, part i., two varieties of silver nitrite : P. C. Ray 

 and A. C. Ganguli. The a variety of silver nitrite is 

 prepared by double decomposition between solutions of 

 silver nitrate and sodium nitrite. The B variety is obtained 

 by dissolving the a variety in boiling water, and from the 

 hoi -aturated solution the nitrite is allowed to crystallise. 

 The two forms show differences in crystalline structure 

 and mode of decomposition by heat. — The products of 

 heating silver nitrite : E. Divers. The author, while 

 accepting Ray and Ganguli 's experimental data, dissents 

 from the view that these are two forms of silver nitrite. — 

 A contribution to the chemistry of benzoic sulphinide : 

 F. D. Chattaway. When chlorine is passed into a solu- 

 tion of the sodium salt of saccharin, o-benzoic -V-chloro- 

 sulphinide or chloroiminosaccharin is precipitated. An 

 account of the properties of this substance is given. — The 

 action of heat on o-hydroxycarboxylic acids, part ii., 

 o-hydroxymargaric acid, a-hydroxypalmitic acid, a-hydroxy- 



