February 2, 1899] 



jVA TURE 



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enough to cause some leakage. Both resistance and inductance 

 become infinite with infinite damping, and they difler somewhat 

 from the corresponding quantities for undamped waves. — Mr. 

 Rollo Appleyard then described (i) some experiments upon 

 dephlegmators, in which he has attempted to replace the 

 platinum-gauze valves of the ordinary fraclionaling-tubes by 

 bends in the tubes. The general form of the apparatus consists 

 in a series of elongated bulbs, the top of each being connected 

 to the bottom of the one above it by a horizontal S-shaped tube. 

 The vapour condensed in any intermediate bulb falls back 

 into the preceding S-bend. The first portions of the 

 distillate are thus returned to the boiling-flask, leaving a 

 little at each bend to act as a wash for the ascending 

 vapour. At the early stage of distillation the bulbs and bends 

 behave as required, but it is found that at the later stages 

 certain of the bulbs become completely filled with liquid 

 sustained by the upward pressure of the vapour, and unless 

 the heating is very carefully managed " Geyser " actions may 

 take place. Some arrangement of overflow tubes is therefore 

 required for the bulbs. Mr. Appleyard also exhibited (2) a 

 temperature tell-tale, to be used in connection with vats and 

 for other purposes where an alarm is to be sounded by making 

 electric contact when temperature rises or falls beyond certain 

 limits. A J-shaped glass tube has its short limb sealed and its 

 long limb open. Water or other suitable liquid is poured in, 

 completely filling the short limb. Mercury is then made to 

 displace nearly all the water in the short limb : the surplus 

 water in the long limb is removed by a pipette, and the mercury 

 is adjusted to a convenient level. Two platinum contact- 

 wires are sealed into the glass at a short distance above the free 

 surface of mercury in the long limb. The tube may be half an 

 inch in diameter, with a long limb of 5 inches, and a short limb 

 of 2j inches. The quantity of mercury in the tube is generally 

 arranged so that at temperatures below the boiling-point of the 

 contained liquid, the mercury level is lowest in the long limb. 

 In this case, if the temperature is raised to the boiling-point of 

 the contained liquid, the mercury assumes appro.ximately a 

 common level in both limbs, for at the boiling-point of the 

 liquid, under these conditions, the vapour-pressure is equal to 

 the barometric pressure. Hence, the liquid and the mercury 

 are not spurted out. Mr. Whopple said that when working 

 with an ordinary "thermometer" tube, the contacts were in- 

 efficient owing to oxidation. Moreover the mercury column 

 broke up, and in some cases mercury clung to the contact- 

 wire. He asked if these difficulties occurred in Mr. 

 Appleyard's apparatus. Jlr. Watson suggested that in some 

 cases the long limb might with advantage be closed. 

 With regard to the dephlegmator he thought that the 

 bends should each be duplicated by a short tube, so as 

 to provide one path for the descending liquid and another for 

 the ascending vapours. This seemed to be the object of the 

 platinum gauze in fractionating-tubes. Mr. Appleyard, in 

 reply, explained that the change of level in the " tell-tale " was 

 a sudden rise of about an inch of mercury, in a tube half an 

 inch in diameter. This rise was able completely to envelope 

 the contact wires, surface oxidation could not afiect the work- 

 ing, and there could be no such thing as failure of contact. 

 Moreover, the tube was too wide for mercury to be held up by 

 capillarity. The large area of contact enabled the instrument 

 to be used for strong currents. The cost was small, and the 

 only adjustment consisted in choosing a liquid of suitable boil- 

 ing-point ; for the platinum wires could be sealed in anywhere 

 in the long limb ; about two and a half inches from the bottom 

 was a good position for them. The sudden rise occurred when 

 the temperature was one gr two degrees above the boiling-point 

 of the contained liquid. — Mr. T. H. Littlewood then read a 

 paper on the volume-changes which accompany solution, 

 and described an apparatus for measuring the contraction 

 observed when solids are dissolved in a liquid. Two glass 

 bulbs are arranged one above the other, so. that liquid can pass 

 from the upper one to the lower one through a stop-cock, and 

 from the lower one upwards into the neck of the upper one 

 through a second stop-cock. This neck, which forms the top 

 of the upper bulb, is fitted with an india-rubber stopper. The 

 lower bulb istubulured, and provided with a glass stopper. A 

 horizontal capillary tube is fitted into the india-rubber stopper, 

 so that volume changes can be determined, after the manner of 

 using Bunsen's calorimeter. The weighed solid is introduced 

 at the tubulure. The measured amount of water is poured in at 

 the neck. Paraffin oil is now poured in at the tubulure so that 



NO. 1527, VOL. 59J 



the apparatus is completely filled : the lower bulb with the solid 

 and the oil, the upper bulb with the water. The apparatus is 

 then exhausted, and finally it is placed in a tank of water at 

 constant temperature. When the stop-cock between the bulbs 

 is opened, solution begins, and the resulting contraction is 

 measured. For small amounts of salt dissolved in constant 

 volume of liquid, the contraction is very nearly proportional to 

 the amount of salt. For larger amounts, the contraction is 

 greater in proportion than the added salt. If a strong solu- 

 tion is gradually diluted, then for equal amounts of water 

 added, the contraction becomes smaller for successive amounts 

 of added water. Mr. Littlewood applies Ostwald's theory, 

 and the theory of Van der Waals to the observed results, 

 and expresses the contraction as a logarithmic function 

 of the volumes and the internal pressures. Mr. Lehfeldt 

 thought the india-rubber stopper was a weak point in the 

 apparatus. With regard to the theory of the contraction, 

 Tammann (Zeitschr. fiir Phys. u. C/iem., 1895), had given an 

 expression which was rather more intelligible. Tammann found 

 that the effect could be regarded as equivalent to a change of 

 pressure, and by attributing this quality to the solution, the 

 characteristic surface becomes the same as that for water. The 

 volume of the solution would thus follow similar changes to 

 those that water undergoes with increasing pressures. Prof. 

 Ewing said the experiments reminded him of the very first 

 piece of research work he had done in physics, which was 

 twenty-five years ago, on the same problem, with Mr. McGregor. 

 An examination of the electrical properties of solutions of 

 certain salts led to an investigation of their changes of density 

 and volume. In some cases the contraction observed was so 

 great that the volume of the solution was less than the original 

 volume of the water to which the salt had been added. They 

 made some measurements, but the apparatus they had used 

 was very rough compared to that described by Mr. Littlewood. 

 Mr. Watson asked whether Mr. Littlewood had made any 

 simultaneous density measurements. There were some solu- 

 tions for which the contractions and corresponding densities had 

 been worked out. By examining successive dilutions of strong 

 solutions, and the corresponding densities, a check might be 

 made as to the numerical results obtained by Mr. Littlewood's 

 apparatus. Dr. Chree suggested that in place of the logarithmic 

 expression, the total contraction might possibly be better repre- 

 sented by a few terms of a series involving increasing powers of 

 the difference of volume, each term being multiplied by a 

 proper constant. Mr. Littlewood, in reply, said that the india- 

 rubber stopper possessed advantages in regulating the height of 

 the capillary tube. It did not introduce sensible error, for it 

 was possible to work with it to a centigram of mercury in the 

 capillary. On the other hand temperature-changes of one-tenth 

 of a degree involved one centigram more or less of mercury in 

 the tube. Bunsen, using an india-rubber stopper, obtained very 

 accurate results in calorimetry. 



Zoological Society, January 17. — Dr. Albert Giinther, 

 F. R.S., Vice-President, in the chair. — Dr. F. P. Moreno ex- 

 hibited and made remarks upon the original specimen of the 

 recently-described Mammal Ntomylodon listai, which he 

 believed to be a portion of the skin of one of the old Pampean 

 Mylodons now quite extinct. — Mr. Sclater read some extracts 

 from letters recently received from Mr. J. S. Budgett, who had 

 been sent by the Council on a scientific mission to the Gambia. 

 — Mr. .Alfred H. Cocks, exhibited some living specimens of 

 supposed hybrids between the stoat i and ferret S . — Mr. R. 

 E. Holding exhibited and made remarks upon some deformed 

 antlers of a fallow deer and of lan axis deer. The abnor- 

 mality in the former was thought to be due to imperfect 

 formation of the " burr," and that of the latter to continued 

 bad health.— Mr. G. E. H. Barrett-Hamilton exhibited some 

 skins of continental squirrels which showed remarkable seasonal 

 changes in coloration, and pointed out their differences from 

 British specimens. — Dr. Arthur Willey gave an account of his 

 itinerary, in the years 1894 to 1897, wlijle in search of the eggs 

 of the pearly nautilus. His travels took him to New Britain,. 

 New Hanover, New Guinea, Sydney, New Caledonia, the 

 Loyalty Islands, and elsewhere. In addition to results con- 

 nected with the main object of the journey, the author cle- 

 scribed a number of collateral results which were of special 

 interest. These related largely to animals which occupy a 

 low position in the scale of the animal kingdom, and repre- 

 sent vestiges of what were in all probability predominant 



