530 



NATURE 



[October i, 189] 



■duties. Mr. D. McAlpine, who has been appointed consulting 

 vegetable pathologist, presents the following summary of 

 the tasks undertaken by his particular section: (l^ special in- 

 vestigations concerning the rust of wheat, oats, barley, and other 

 cereals, and, connected with that, the question of rust on 

 various grasses — native and imported ; (2) investigations of the 

 life-histories of the various fungus pests, and a knowledge of 

 the best time to cope with them ; (3) reports upon diseased speci- 

 mens sent in from different parts of the colony, and the best 

 known remedies for the palliation or prevention of such diseases ; 

 (4) collection of specimens of the various diseases due to fungi, 

 and the subsequent formation of a museum for educational pur- 

 poses ; (5) delivery of lectures in different centres'on the fungus 

 pests most prevalent there ; (6) preparation of illustrated hand- 

 books, describing the nature of the various diseases and the 

 remedies to be employed where possible ; (7) testing various 

 fungicides and the best methods of applying them ; (8) visiting 

 different districts in order to find out prevailing and injurious 

 fungi ; (9) contributing periodic reports to the official Bulletin 

 of the Department. 



In the Proceedings of the Bath Natural History and Anti- 

 quarian Field Club (vol. vii. No. 2), Mr. J. F. Mostyn Clarke 

 gives an account of the geological formations exposed in the 

 cuttings of the Bridgwater Railway, the construction of which 

 opened up a continuous line of excavation through the heart 

 of the Polden Hills. Mr. Clarke had charge of the con- 

 struction of the railway until near the completion of the earth- 

 work, so that he had excellent opportunities for making careful 

 observations. • Geologists may be glad to have his description of 

 the strata when the slopes of the cuttings are overgrown. 



Messrs. Longmans, Green, and Co. have published the 

 sixth edition of "An Elementary Treatise on the Integral 

 Calculus," by Dr. Benjamin Williamson, F.R.S. In this edition 

 the work has been revised and enlarged. 



Messrs. Mitscher and Rostell, 6ia Jagerstrasse, Berlin, 

 have issued an important list of books which they have for sale. ' 

 The works relate to the various departments of botany. 



Two communications upon the volatile carbonyl compounds 

 of platinum, from Dr. Pullinger, of Tiibingen, and Drs. Mylius 

 and Foerster, of Charlottenburg, appear in the last number of 

 the Berichte. Since the preparation of the remarkable carbonyl 

 compounds of nickel and iron by Messrs. Mond, Langer, and 

 Quincke, these platinum compounds, discovered by Schutzen- 

 bergerin the year 1868, have become more interesting, and the 

 two papers now before us add considerably to our knowledge of 

 them. They are compounds containing platinum, chlorine, and 

 carbon monoxide, and Schutzenberger assigned to them the 

 formulas PtClgCO, PtClo . 2CO, and 2PtCl2 . 3CO respectively. 

 He obtained them by heating spongy platinum to a tempera- 

 ture of 250° C. in a stream first of chlorine and afterwards of 

 carbon monoxide. The volatile, readily fusible, and crystalline 

 sublimate obtained contained a mixture of the three, and he 

 effected a separation by extraction with carbon tetrachloride, in 

 which the three compounds are differently soluble. They 

 are well defined by their melting-points, which are 194°, 

 142°, and 130° C. respectively. They are decomposed 

 by water with separation of platinum, formation of hydro- 

 chloric acid, and evolution of carbon dioxide, and also, in 

 case of the second and third compounds, of carbon monoxide. 

 The most stable of these compounds and the best investigated 

 is the simpler one, COPtCU. It appears to possess a distinctly 

 basic character, so that it is able to combine with hydrochloric 

 acid to form a compound, COPtClj . HCl ; this compound is 

 formed in solution when the crystals are dissolved in concen- 

 trated hydrochloric acid. The two other compounds are decom- 

 posed by hydrochloric acid, losing carbon monoxide and forming 

 the hydrochloride of the first compound. On evaporation of 

 NO. II 4 4, VOL. 44] 



the hydrochloric solution, the first compound is left in needle- 

 shaped crystals. When phosgene gas, COCIj, is passed over 

 the crystals, drops of liquid are formed, which consist of a solution 

 of the compound in liquefied carbonyl chloride. In addition to 

 these compounds, the bromide and iodide corresponding to the 

 compound COPtClg have been prepared. When the hydro- 

 chloric acid solution of the latter is evaporated on a water- 

 bath in a stream of hydrobromic acid gas, and the resulting 

 compound extracted with benzene, the filtered solution de- 

 posits, on cooling, orange-red needles of the bromi le, 

 COPtBrg. The bromide has likewise been obtained by Dr. 

 Pullinger, by passing carbon monoxide over heated platinous 

 bromide. Similarly, the iodide has been prepared by evaporat- 

 ing crystals of the chloride with excess of hydriodic acid solu- 

 tion, and treating the residue with warm benzene. The crystals 

 of the iodide, COPtlj, which separate from the benzene solution 

 on cooling, are deep red in colour, with a violet surface reflec- 

 tion. The chloride, bromide, and iodide exhibit a beautifully 

 graduated difference of properties. Thus the chloride is yellow, 

 the bromide orange, and the iodide red in colour. The melting- 

 points are 194°, 181°, and 140° respectively. The chloride is 

 readily, the bromide difficultly, and the iodide not at all volatile. 

 The chloride is strongly \ hygroscopic, the bromide less so, 

 and the iodide permanent. In addition to these compounds, 

 another has been obtained by Dr. Pullinger, of the composition 

 PtCU . 2COCI2, in the form of non-volatile yellow crystals, 

 readily soluble in water, from which it recrystallizes unchanged. 

 It appears to be the most stable of all these platinum compounds, 

 but is only obtained in very small quantity. 



OUR ASTRONOMICAL COLUMN. 



Influence of Aberration upon Observations of 

 Solar Prominences. — Some recent observations of the deve- 

 lopment and movement of solar prominences have led M. Fizeau 

 to consider the influence that the aberration of light may exer- 

 cise upon them. A note relative to such an inquiry is contained 

 in Coviptes rendus for September 7. It is well known that, in 

 consequence of aberration, the longitude of the sun, and there- 

 fore of the prominences, is diminished by the amount of the 

 constant, 20" '445 — an apparent displacement depending upon 

 the earth's orbital velocity. And it results from this that if a 

 prominence is developed in the neighbourhood of the ecliptic, 

 and the luminous matter of which it is composed has a velocity 

 of translation equal to the velocity of the earth in its orbit, its 

 position will suffer a displacement of 2o""445, which may be 

 added to the effect due to the earth's motion, or otherwise, 

 according to the direction of propagation, and thus give rise to 

 corresponding variations in distances from the edge of the sun. 

 As a matter of fact, however, the velocities of prominences are 

 not uniform, and do not commonly attain the required value ; 

 nevertheless it seems that the high velocities which have been 

 determined must give rise to apparent movements which depend 

 upon the laws of aberration, and which ought to be taken into 

 account in precise measurements. 



Another point touched upon in the communication to which 

 reference has been made is the physical nature of promin- 

 ences. The simplest hypothesis is that they represent clouds of 

 incandescent hydrogen and other metallic vapours ; but M. 

 Fizeau favours the idea that their visibility is the result of the 

 passage of electrical discharges through gaseous material. 



New Asteroids.— The 317th asteroid was discovered by 

 Charlois on September 8, and the 318th on September 11. 



SOME OF THE POSSIBILITIES OF ECONOMIC 



BOTANY > 

 (^UR Association demands of its President, on his retirement 

 ^^ from office, some account of matters connected with the 

 department of science in which he is engaged. 



The subject which I have selected for the valedictory address 



' Abstract of the Presidential address delivered before the American 

 Association for the Advancement of Science, at Washington, August 1891, by 

 George Lincoln Goodale, M D., LL.D.. Fisher Professor of Natural History, 

 Harvard University, Cambridge, Mass., U.S.A. 



