June 2;, 1889J 



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Bisk of mica, or by a fish-lens. (3) Expansion and contraction, 

 Ry transverse electrification, of the rings seen in quartz by con- 

 vergent polarized light. (4) Objects electro-plated with the 

 metal cobalt (new process). 



Exhibited by the Hon. Ralph Abercromby : — Photo<4raphs 

 and specimen, and map, illustrative of the nitrate of soda 

 industry, and of the nitrate country. — Sun distilling apparatus, 

 on the Atacama desert. This apparatus is situa'ed at Sierra 

 Gorda, near Caracoles, and is the property of Signor Oliveira. 

 It consists of 1875 square feet of glass, something like a row of 

 cucumber frames. A thin layer of salt water is led under the 

 glass, when the heat of the sun vaporizes some of the water, 

 which condenses as a sweat on the under surface of the glass 

 top. The drops gradually coalesce, trickle down into the 

 narrow groove on which the panes of glass rest, and are then 

 led by pipes into a reservoir of fresh water. The bars along the 

 outside of the glass are to save the apparatus from being wrecked 

 by whirlwinds. Raiher more water distils by night than by 

 day, owing to the belter condensation when the outer air is cool. 

 At the time of my visit the outer air was 97°, the air inside the 

 frames 120°, and that of the salt water inside only 117°, while 

 that of the glass frame itself could not be determined. The 

 apparatus is extremely inefficient, owing to the ab.-ence of a 

 proper condenser, and the details are bad ; still, from 150 to 175 

 litres of fresh water are distilled every day, which is sold at a 

 profit for \\d. a gallon. Twenty years ago a similar apparatu-, 

 with 50,000 square feet of glass, was erected at Carmen Alto 

 on the same desert, and worked very profitably, as ^os. a gallon 

 could then be obtained for fresh water. This apparatus was 

 afterwards wrecked by a whirlwind, and is now replaced by a 

 steam condenser. 



Exhibited by Mr. Streeter •.—Rubies from the Burmah Mines, 

 English cut and mounted, and in the rough as found. 



Exhibited and invented by Mr. Ludwig Mond and Dr. Carl 

 Langer : — New form of gas battery. This battery is an im- 

 provement on the well-known gas battery invented by Grove 

 fifty years ago, which produces electricity from hydrogen and 

 oxygen gas by the intervention of platinum. The distinguishing 

 feature of the new battery, which has been designed to obtain 

 large currents of electricity by means of these gases, is that the 

 electrolyte is not emp'oyed as a mobile liquid, but in a quasi- 

 solid form, and it is therefore named "dry gas battery." Each 

 element of the battery consists of a porous diaphragm of a non- 

 conducting material — for instance, plaster of Paris — which is 

 impregnated with dilute sulphuric acid. Both sides of this dia- 

 phragm are covered with very fine platinum leaf, perforated 

 with very numerous small holes, and over this with a thin film 

 of platinum b'ack. Both these coatings are in contact with 

 frame-works of le.ad and antimony, insulated one from the other, 

 which conduct the electricity to the poles of each element. 

 A number of these elements are placed side by side, or one 

 above the other, with non-conducting frames intervening, 

 so as to form chambers through which hydrogen gas is 

 passed along one side of the element, and air along the other. 

 One element, with a total effective surface of 774 square centi- 

 metres = 120 square inches, which is covered by i gramme of 

 platinum black and 0*35 gramme of platinum leaf, shows an 

 electromotive force of very nearly i volt when open, and pro- 

 duces a current of 2 amperes and 07 volt or i '4 watt, when the 

 outer resistance is properly adjusted. This current is equal to 

 nearly 50 per cent, of the total energy obtainable from the 

 hydrogen absorbed in the battery. 'I he electromotive force 

 decreases, however, slowly, in consequence of the transport of 

 the sulphuric acid from one side of the diaphragm to the other. 

 In order to counteract this disturbing influence the gases are 

 from time to time interchanged. The battery works equally 

 well with gases containing; 30 to 40 per cent, of hydrogen, 

 such as can be obtained by the action of steam or steam 

 and air on coal or coke, if the gases have been sufficiently 

 purified from carbonic oxide and hydrocarbons. The water 

 produced in the battery by the combination of hydrogen and 

 oxygen is carried off by the unconsumed nitrogen and an excess 

 of air carried through it for this purpose. 



Exhibited by Messrs. Woodhouse and Rawson, Ltd. : — 

 Samples of copper produced by the Elmore depositing process. 

 Sketches of the appearance under the microscope of ordinary 

 deposited copper, and copper made by the Elmore process. By 

 the Rev. F. Howlett, F.R.A.S. 



Exhibited by Prof. J. A. Fleming, D.Sc. : — Edison Swan 

 incandescence lamp-, showing the " Edison eff'ect." If a carbon 



NA JURE 



21 1 



incandescence lamp has a platinum plate, carried on a wire 

 sealed through the glass, placed between the loop or horse-shoe, 

 it is found that when the lamp is in action a galvanometer 

 connected between the middle plate and the positive side of the 

 carbon loop shows a current passing. If the galvanometer is 

 placed between the middle plate and the negative side of the loop 

 n ) current is found. The lamps exhibited show this effect very 

 well. It was first pointed out by Mr. Edison, in 1884. It has 

 been found that shielding the nega'.ive leg by a glass or metal 

 tube entirely steps the production of the eiTect. 



Exhibited by the Director of the Royal Gardens, Kew : — 

 Photographs of Ceylon vegetation. 



Exhibited by Mr. J. Young: — (i) A cluster of nests of a 

 species of swift (Collocalia) taken in one of the Society Islands. 

 (2) A sptcimen cf Phivianelhis sociaHlis, a plover obtained 

 in South America, of which only two specimens (obtained fifty 

 years ago) were previously known in Europe. (3) The tail of a 

 Japanese barndoor cock, 11 feet long. (4) Bearded-tits' 

 nest, built in Pampas grass heads, stuck in a flower-pot in an 

 aviary. 



Exhibited by Mr. P. L. Sclater, F.R.S. :— (l) Head of Thom- 

 son's g&zeWe {Gaze/la thoinsoni), from a specimen shot by Mr. H. 

 C. V. Hunter, in Masai Land, Eastern Africa. This gazelle 

 was discovered by Mr. Joseph Thomson during his expedition 

 through Masai Lanoxin 1883-84, and named after its discoverer 

 by Dr. Giinther {Ann. Nat. Hist., ser. 5, vol. xiv. p. 427). (2) 

 Head of Grant's gazelle {Gazella granti), from a specimen shot 

 by Mr. Frederick Holmwood, C.B., in the Kilimanjaro district 

 of Eastern Africa. This gazelle was discovered by Colonel 

 Grant, C.B., F.R.S. , in Ugogo, in i860, and named after him^ 

 by Sir Victor Brooke (P.Z.S., 1872, p. 601). (3) Mummy of a 

 small falcon (probably the kestrel, Tinnunciilics alatidaritis) 

 from the tombs at Thebes in Egypt, obtained from the natives 

 by Mr. A. G. Scott. (4) Tray of birdskins, from St. Lucia, 

 West Indies, collected by Mr. Ramage, the naturalist employed 

 by the joint Committee of the Royal Society and British 

 Association for the exploration of the Lesser Antilles. 



Exhibited by Profs. Liveing and Dewar, F.R.S.: — Absorp- 

 tion spectrum of oxygen. The oxygen, compressed to \y> 

 atmospheres, is contained in a steel tube fitted with quartz ends. 

 In the red part of the spectrum are seen the absorptions corre- 

 sponding to the Fraunhofer groups A and B. Less sharply 

 defined absorption bands are seen in the orange, citron, and 

 blue, and faint bands in the green and indigo. These band 

 absorptions have a totally different character from the great line- 

 absorptions of A and B. Beyond the visible spectrum, photo- 

 graphs show some absorptions in the ultra-violet, and the extreme 

 ultra-violet rays are wholly absorbed. This complete absorption 

 extends nearly to the limit of the solar spectrum. This proves 

 that the earth's atmosphere limits the rays which can reach us 

 from the outside. Ozone has even a more powerful absorptive 

 action, and oxygen, ozonized and unozonized, put a limit to our 

 observations of stellar spectra. Profs. Liveing and Dewar have 

 experimented with a steel tube 60 feet in length, and easily 

 capable of holding a mass of oxygen equal to that contained in 

 a vertical column of the earth's atmosphere of equal section. 



Exhibited by Mr. Francis Galton, F.R.S: — Reaction-time 

 instrument (working model). The time is measured by a half- 

 second pendulum. The signal is the sharp sound made by a 

 small hammer (noiselessly set free) on its striking a detent, and 

 thereby releasing the pendulum. The response is made by 

 touching a key that releases an arrangement (worked very quickly 

 by a spring) whereby an elastic thread, which is secured above 

 and below to the pendulum, parallel to its rod, but not touching 

 it, is nipped and held fast against a horizontal bar. The bar is 

 graduated to hundredths of a second, so that the graduation 

 opposite to the thread shows the elapsed time between the signal 

 and the response. The pendulum receives no jar, and continues 

 to vibrate. 



Exhibited by the Hon. A. Holland-Hibbert :—(l) Old tele- 

 scope, with parchment tubes. (2) Old microscope, of stamped 

 leather. Both formerly the property of King Charles I. 



Exhibited by Mr. Fred. Enock : — Microscopical preparations 

 illustrating the life-history of the Hessian fly {Cecidomyia 

 destructoj-. Say). 



Exhibited by Mr. Percy E. Newberry, by kind permission of 

 the Director of the Royal Gardens, Kew : — A series of ancient 

 funeral wreaths and p'ant remains, discovered last year by Mr. 

 W. M. Flinders Petrie, in the cemetery of Hawara, Egypt. 

 (I.) 'J he wreaths, which are of Egyptian and Greek manufacture. 



