300 



NA TURE 



{Aug. 12, 1875 



the various positions of i' ; N. American continent were greatly 

 changed ; and this co .sicleration will aid in accounting, he 

 thinks, for the curious fact that the ice in the eastern seaboard 

 stretched unbroken past the fortieth parallel, while under the 

 same latitude in the Cordilleras no glaciers formed below 9,000 

 feet. 



The third part of the second series of the magnificent work o 

 Mr. William H. Edwards upon the Butterflies of North America 

 has been published by Messrs. Hurd and Houghton, of Cam- 

 bridge, Massachusetts, and embraces five plates, executed by 

 Miss Mary Peart. The plates represent species of Papilio, 

 Argynnis, Apahira, Chionobas, and Lyavrta ; all of them being 

 rare and, for the most part, unfigured species, and also many 

 but recently described. 



We have received the Journal of the Anthropological Society 

 for April and July, containing in full the papers which have 

 appeared in abstract in our reports of the meetings of the Society. 

 Many of the papers are of great value, and the illustrations, 

 especially those of the Andamanese, are very interesting. 



It is rumoured that, on the retirement of Sir Henry James 

 from the directorship of the Ordnance Survey, a post which he 

 has filled during a lengthened period with so much distinction, 

 he will be succeeded by Col. A. Ross Clarke. We congratulate 

 the Government on this selection, just at once to a most meri- 

 torious officer and to Science and the State. Col. Clarke's 

 eminence as a mathematician and a geodesist are too highly 

 appreciated wherever those sciences are cultivated, both at home 

 and abroad, to need any comment from us. 



The additions to the Zoological Society's Gardens during the 

 past week include a Manatee {Manatus americanus) from 

 Demerara, a Ground Hornbill {Bucorviis abyssini(us), a White- 

 thighed Colobus [Colobus bicolor) from West Africa, a Rose- 

 crested Cockatoo {Cacatua moluccensis) from Moluccas, de- 

 posited ; two Jaguars {Felis onfo) from America, a Squirrel 

 Monkey {Saimaris sciurea) from Brazil, purchased ; four Amherst 

 Pheasants ( Thaumalea amherstice), a Siamese Pheasant {Euplo. 

 camus prcclatus), and two Vinaceous Doves (Turtur vinauus) 

 bred in the Gardens. 



PHYSICAL PROPERTIES OF MATTER IN 

 THE LIQUID AND GASEOUS STATES* 



'X'HE investigation to which this note refers has occupied me, 

 •^ with little intermission, since my former communication in 

 1869 to the Society, "On the Continuity of the Liquid and Gaseous 

 States of Matter." It was undertaken chiefly to ascertain the 

 modifications which the three great laws discovered respectively 

 by Boyle, Gay-Lussac, and Dalton undergo when matter in the 

 gaseous state is placed under physical conditions differing greatly 

 from any hitherto within the reach of observation. It embraces 

 a large number of experiments of precision, performed at 

 different temperatures and at pressures ranging from twelve to 

 nearly three hundred atmospheres. The apparatus employed is, 

 in all its essential parts, similar to that described in the paper 

 referred to ; and so perfectly did it act that the readings of the 

 cathetometer, at the highest pressures and temperatures em- 

 ployed, were made with the same ease and accuracy as if the 

 object of the experiment had been merely to determine the 

 tension of aqueous vapour in a barometer-tube. In using it the 

 chief improvement I have made is in the method of ascertaining 

 the original volumes of the gases before compression, which can 

 now be know with much less labour and greater accuracy than 

 by the method I formerly described. The lower ends of the 

 glass tubes containing the gases dip into small mercurial reservoirs 

 formed of thin glass tubes, which rest on ledges within the 

 apparatus. This arrangement has prevented many failures in 

 screwing up the apparatus, and has given more precision to the 



* •' Preliminary Notice of further Researches on the Physical Properties 

 of Matter in the Liquid and Gaseous States under varied conditions of Pres- 

 sure and Temperature." Paper read before the Royal Society by Dr. 

 Andrews, F.R.S., Vice-President of Queen's CoUege, Belfast. 



measurements. A great improvement has also been made in the 

 method of preparing the leather-washers used in the packing for 

 the fine screws, by means of which the pressure is obtained. It 

 consists in saturating the leather with grease by heating it in 

 vacuo under melted lard. In this way the air enclosed within 

 the pores of the leather is removed without the use of water, 

 and a packing is obtained so perfect that it appears, as far as my 

 experience goes, never to fail, provided it is used in a vessel 

 filled with water. It is remarkable, however, that the same 

 packing, when an apparatus specially constructed for the purpose 

 of forged iron was filled with mercury, always yielded, even at a 

 pressure of forty atmospheres, in the course of a few days. 



It is with regret that I am still obliged to give the pressures in 

 atmospheres, as indicated by an air- or hydrogen manometer, 

 without attempting for the present to apply the corrections 

 required to reduce them to true pressures. The only satisfactory 

 method of obtaining these corrections would be to compare the 

 indications of the manometer with those of a column of mervcury 

 of the requisite length ; and this method, as is known, was em- 

 ployed by Arago and Dulong, and afterwards in his classical 

 researches by Regnault, for pressures reaching nearly to thirty 

 atmospheres. For this moderate pressure a column of mercury 

 about 23 metres, or 75 feet, in length had to be employed. For 

 pressures corresponding to 500 atmospheres, at which I have no ' 

 difficulty in working with my apparatus, a mercurial column of 

 the enormous height of 380 metres, or 1,250 feet, would be 

 required. Although the mechanical difficulties in the construc- 

 tion of a long tube for this purpose are perhaps not insuperable, 

 it could only be mounted in front of some rare mountain escarp- 

 ment, where it would be practically impossible to conduct a long 

 series of delicate experiments. About three years ago I had the 

 honour of submitting to the Council of the Society a proposal 

 for constructing an apparatus which would have enabled any 

 pressure to be measured by the successive additions of the pres- 

 sure of a column of mercury of a fixed length ; and working 

 drawings of the apparatus were prepared by Mr. J. Cumine, whose 

 services I am glad to have again this opportunityof acknowledging. 

 An unexpected difficulty, however, arose in consequence of the 

 packing of the screws (as I have already stated) not holding 

 when the leather was in contact with mercury instead of water, 

 and the apparatus was not constructed. For two years the 

 problem appeared, if not theoretically, to be practically impos- 

 sible of solution ; but I am glad now to be able to announce to 

 the Society that another method, simpler in principle and free 

 from the objections to which I have referred, has lately suggested 

 itself to me, by means of which it will, I fully expect, be possible 

 to determine the rate of compressibility of hydrogen or other 

 gas by direct reference to the weight of a liquid column, or 

 rather of a number of liquid columns, up to pressures of 500 or 

 even 1,000 atmospheres. For the present it must be understood 

 that, in stating the following results, the pressures in atmospheres 

 are deduced from the apparent compressibility, in some cases of 

 air, in others of hydrogen gas, contained in capillary glass tubes. 



In this notice I will only refer to the results of experiments 

 upon carbonic acid gas when alone or when mixed with nitrogen. 

 It is with carbonic acid, indeed, that I have hitherto chiefly 

 worked, as it is singularly well adapted for experiment ; and the 

 properties it exhibits will doubtless, in their main features, be 

 found to represent those of other gaseous bodies at corresponding 

 temperatures below and above their critical points. 



Liquefaction of Carbonic Acid Gas. — The following results 

 have been obtained from a number of very careful experiments, 

 and give, it is believed, the pressures, as measured by an air- 

 manometer, at which carbonic acid liquefies for the temperatures 

 stated :— 



Temperatures in Pressure in 



Centigrade degrees. atmospheres. >:.:;a 



o 35-04 



5'45 40-44 



"•45 

 16-92 



22-22 



25-39 

 2^-30 



47-04 



53-77 

 61-13 

 65-78 

 70-39 



I have been gratified to find that the two results (for 13° "09 

 and 2i°-46) recorded in my former paper are in close agreement 

 with these later experiments. On the other hand, the pressures 

 I have found are lower than those given by Regnault as the 

 result of his elaborate investigation {Memoires de V Academie des 

 Sciences, vol. xxvi. p. 618). The method employed by that 

 distinguished physicist was not, however, fitted to giye accurately 



