August 23, 1894] 



NA TURE 



415 



Nicholls, 23, engineer, of Pontefract, obtained the third place 

 in order of merit in the competition for National Scholarships, 

 &c., but withdrew before the awards were actually made. 



The separation of minerals of high specific gravity has 

 recently been greatly facilitated by the introduction of the 

 fused double nitrate of silver and thallium, originally due to 

 Dr. J. \V. Retgers. When these nitrates are brought tigether 

 in the molecular proportion of I : I, they yield a double salt, 

 which fuses at 75° C. to a clear, mobile liquii, having a 

 specific gravity of about S and miscible with water in all pro- 

 portions at temperatures between its melting point and too" C. 

 The melting point also diminishes rapidly as water is added, 

 going down to 50^ or 60° C, and fusion and solubility pass 

 uninterruptedly into one another. We have thus at our 

 command for the separation of mineral particles a liquid far 

 exceeding in specific gravity any of the previously described 

 heavy solutions, and which has the advantage of being practi- 

 cally colourless, neutral, soluble in water, and of being readily 

 recovered from the aqueou5 solution by simple evaporation on 

 the water bath. Some further hints upon the use of this 

 convenient medium are given in the current number of the 

 American Journal of Science, by Messrs. Penfield and Kreider. 

 Separations may be made in test tubes heated in a water bath. 

 After a separation is completed and the fusion cooled, the 

 test tube is broken and the solid cake divided, when the 

 heavier and lighter portion may be obtained by dissolving the 

 double salt. If fractional separations are required, the fused 

 salt may be placed in a tube with a narrow neck at the bottom, 

 into which is ground a glass rod to serve as a stopcock. This 

 apparatus slips inside of a test lube to within a few millimetres 

 of the bottom. The whole is heated in a beaker of hot water, 

 and the liquid is stirred by means of a glass rod bent into a 

 semicircle at the bottom. Heavy particles are drawn off by 

 raising the ground gla.ss rod. Small particles getting caught in 

 the stopper can usually be ground out by twisting the rod, but 

 in no case will such an accident cause great inconvenience. 



The annual report for 1893, just received from the Depart- 

 ment of Mines and Agriculture, New South Wales, states that 

 the Government metallurgical works will probably be started 

 this year. These works in conjunction with the .School of 

 Mines which has been established at the .Sydney University, 

 enables the colony to offer as complete and effective a course 

 of training in mining and metallurgy as can be obtained in 

 Great Britain. The report consists largely of statistics relating 

 to the output, value, &c., of various minerals. A boring made 

 at Cremorne Point is of interest. Prof. T. W. E. David made 

 some determinations of the temperature of this bore. The 

 hole was 2929 feet deep, but the bottom 29 feet (about) was 

 silted up with the powdered rock produced by the cutting 

 action of the diamond drill used in the boring. From 2900 

 feet to within 300 feet of the surface, the bore was filled with 

 water, the column being, therefore, 2600 feet high, and giving 

 a maximum pressure of, approximately, a trifle over half a ton 

 per square inch. The thermometers used were hermetically 

 sealed in wrought -iron tubes and surrounded with brass filings 

 and brass turnings. The readings obtained showed that the 

 rock temperature at a depth of 2730 feel was 97''5 F. The 

 mean surface temperature at Sydney is about 63' F., so the 

 rate of increase was 1° F. for about every 78 feet 10 inches. 



The Bulletin of the Royal Gardens, Kew, No. 92, for 

 August 1894, is entirely occupied by a summary of information 

 relating to Bananas and IM.intain^, with descriptions of the 

 species and principal varieties of Mtisa grown for use and 

 ornament. 



NO. 1295, VOL. 50] 



From thirty to forty volumes are issued yearly in the com- 

 prehensive " Encyclopedie Scientinque des Aide-Memoire " 

 series published jointly by MM. Gauthier-Villars and M. 

 Masson. The whole collection, when completed, will number 

 three hundred volumes. The latest addition to the series is 

 "Les Machines Thermiques," by Prof. Aimc Witz. The 

 theory of steam, hot air, and gas engines is well described by 

 the author, and the relations between different heat engines are 

 set forth in a manner which brings out clearly the special 

 characters of their respective cycles. 



The third volume of the Seismological "Journal of Japan, 

 corresponding to the Transactions of the Seismological Society, 

 has reached us. Prof. John Milne, F.R.S., contributes to it a 

 paper on "Seismic, Magnetic, and Electric Phenomena," in 

 which he discusses the evidence as to the connection between 

 those phenomena. Observations are adduced which seem to 

 show that there may be a connection between earthquakes and 

 magnetic and electric manifestations. But, concludes Prof. 

 Milne, though "a varietyof experiments and investigations have 

 been made to test whether earthquakes were preceded, accom- 

 panied, or followed by magnetic or electric phenomena, the 

 results obtained do not guarantee the existence of such con- 

 nections. It does not seem likely that earthquakes can result 

 from electric discharges, and it has not yet been proved that 

 they give rise to electric phenomena. When they have resulted 

 in the displacement of large masses of rocky strata, as happened 

 in 1891 in Central Japan, slight local changes in magnetic 

 curves have resulted, but beyond this and effects due to the 

 mechanical shaking of earth-plates, our certain knowledge is 

 exceedingly small." 



The " Geological Sketch-Map of Western Australia," by Mr. 

 H. P. Woodward, the Government geologist, shows in a very 

 clear manner the geology of the explored districts ; but it also 

 shows of how large an area the geology is quite unknown. The 

 scale is I : 3,000,000 (i inch 1047*3 miles). The rock-divisions 

 coloured are : Recent and Tertiary, Mesozoic, Palasozoic, 

 Metamorphic, Crystalline (schists and granite), Volcanic, and 

 Plutonic (basalt and granite). The distribution is shown of 

 gold, copper, lead, tin, and coal ; gold and copper are indicated 

 by solid colour, which somewhat interferes with the general 

 effect of the map, as the ciloars appear to represent special 

 formations ; the other minerals are shown by coloured lines. 

 The chief gold-fields are situated on metamorphic rocks ; a few 

 are in the crystalline areas. The geology of the Coolgardie and 

 Dundas gold-fields is not indicated. The map is clearly printed, 

 both in its topography and colouring. It is published, for the 

 Government of Western Australia, by G. Philip and Son, Fleet 

 Street, London. 



The Moni't for July contains an interesting article by Mr. 

 Wm. R. Thayer, on Leonardo de Vinci as a pioneer in science. 

 Of the thousands of MS. pages which this indefatigable ex- 

 perimenter left, one volume alone has been edited. At first 

 no one could decipher them, for Leonardo wrote backwards from 

 right to left. The pioneer work in science, astronomy, physics, 

 geology, botany— in fact, the whole circle of the sciences — con- 

 tained in this one volume is briefly but clearly sketched, and some 

 of his pithy and epigrammatic notes are quoted. " His curiosity 

 was insatiable ; his methods were observation and experiment ; 

 his advance was from the known to the unknown. . . . To 

 search out all things, to experiment and verify, to let his eyes 

 test, and reason be the judge. This was Leonardo's method." 

 Prof. Hermann Schubert's article on "Monism in .\rithmetic" 

 is a lucid statement of fundamental principles in continuation 

 of a previous paper on "The Notion and Definition of 

 Number." 



