October 15, 1891] 



NATURE 



S77 



Panjab. He presents a series of tables drawn from the 

 measurement of fifty skulls collected by him in the compara- 

 tive anatomy museum of the Medical College, Lahore. These 

 skulls are, in Dr. Charles's opinion, from individuals of aborigi- 

 nal as distinguished from Aryan progeny, with the exception of 

 certain megacephalic examples among the group of Moham- 

 medan male types. In these exceptional cases descent may 

 be derived from the more recent Mohammedan invaders, who 

 were distinct both from the Aryan possessors on the one hand, 

 and from the dispossessed aboriginal races on the other. 



The Department of Public Instruction in New South Wales 

 has issued a second edition of " Wattles and Wattle-Barks," by 

 J. H. Maiden. It appears as No. 6 of the Technical Education 

 Series. The pamphlet is intended to supply Australian farmers, 

 tanners, merchants, and others with authentic information in 

 regard to the value of wattles. According to the author, the 

 demand for good wattle-bark becomes greater every year, and 

 the supply does not cope with it. The word " wattle," we may 

 note, has become in Australia practically synonymous with 

 "acacia." 



An interestmg experiment has been lately made by M. 

 Chabry, of the Societe de Biologic, with regard to the pressure 

 which can be produced by electrolytic generation of gas in a 

 closed space. While the highest pressure before realized in this 

 way was 447 atmospheres (Gassiot), M. Chabry has succeeded 

 in getting as high as 1200 ; and the experiment was broken off 

 merely because the manometer used got cracked (without ex- 

 plosion). The electrolyzed liquid was a 25 per cent, soda 

 solution. Both electrodes were of iron : one was the hollow 

 Sphere in which the gas was collected ; the other an inner con- 

 centric tube. The current had a strength of i^ ampere, and 

 was very constant during the experiment, which was merely one 

 preliminary to a research in which very high pressures were 

 desired. 



The first series of lectures given by the Sunday Lecture 

 Society begins on Sunday afternoon, October 18, in St. George's 

 Hall, Langham Place, at 4 'p.m., when Sir James Crichlon 

 Browne, F.R.S., will lecture on "Brain Rust." Lectures will 

 subsequently be given by Mr. Frank Kerslake, Mr. Walter L. 

 Bicknell, Mr. W. E. Church, Prof. H. Marshall Ward, F.R.S., 

 Mr. A. W. Clayden, and Sir Robert Ball, F.R.S. 



An important paper upon persulphates is contributed by Dr. 

 Marshall, of Edinburgh, to the October number of the Journal 

 of t/ie Chemical Society. The anhydride of persulphuric acid, 

 S2O7, was obtained by Berlhelot in the year 1878, by subjecting 

 a well-cooled mixture of sulphur dioxide and oxygen to the 

 silent electrical discharge. He afterwards found that a substance 

 possessing oxidizing properties, and which appeared to be per- 

 sulphuric acid, was formed in solution during the electrolysis of 

 fairly strong solutions of sulphuric acid ; it appeared, in fact, to 

 be identical with the substance obtained by dissolving his crystals 

 of S2O7 in water. The anhydride does not dissolve in water 

 without partial decomposition, a considerable proportion decom- 

 posing into sulphuric acid and oxygen, and hitherto no salts of 

 persulphuric acid have been obtained in the solid state. Dr. 

 Marshall has now succeeded in obtaining the potassium, ammo- 

 nium, and barium salts in fine large crystals. During the course 

 of an experiment in which an acid solution of potassium and 

 cobalt sulphates was being electrolyzed in a divided cell, it was 

 found that a quantity of small colourless crystals separated. A 

 solution of these crystals in water gave only a faint precipitate 

 with barium chloride, but on warming barium sulphate slowly 

 separated and chlorine was evolved. I'he solution also liberated 

 iodine from potassium iodide. The crystals were, in fact, potas- 

 sium persulphate, KSO4. It was next sought to prepare them 

 NO. I 146, VOL. 44] 



from hydrogen potassium sulphate. A saturated solution of this 

 salt was submitted to electrolysis in a similar apparatus, and at 

 the end of two days a white crystalline deposit of potassium per- 

 sulphate commenced to form. The crystals were from time to 

 time removed until a considerable quantity of them had been 

 accumulated. These, when recrystallized from hot water, 

 yielded large tabular crystals, and sometimes long prisms when 

 formed at the surface of the liquid. Analyses of pure samples 

 yielded numbers agreeing perfectly with the formula KSO^- 

 From determinations of the conduct ivity of dilute solutions it 

 would appear that the correct molecular formula is KSO4 and 

 not K-jS-jOg. On ignition of the salt, oxygen and sulphuric 

 anhydride are evolved and potassium sulphate is left. The 

 crystals are not very soluble in water, 100 parts of water at 0° 

 dissolving 1 77 part of KSO4. The aqueous solution gradually 

 decomposes, hydrogen potassium sulphate being formed and 

 oxygen liberated. The pure freshly prepared solution is neutral 

 to test paper. The solution yields no precipitate with any other 

 salt by double decomposition, the persulphates of most other 

 metals appearing to be more soluble than potassium persulphate. 

 A solution of lead hydrate in potash yields a precipitate of lead 

 peroxide on boiling. With silver nitrate no immediate precipi- 

 tate is formed, but the liquid gradually acquires an inky appear- 

 ance and after some time a black precipitate of silver peroxide, 

 AgO, is deposited. It would appear that silver persulphate is 

 dissolved by water. Fehling's solution gives a red precipitate of 

 copper peroxide. Ferrous sulphate is rapidly oxidized to ferric 

 with considerable rise of temperature. Organic colouring 

 matters, such as litmus, are bleached. Alcohol is oxidized to 

 aldehyde in presence of water, but absolute alcohol has no action 

 on solid potassium persulphate. The pure crystals have a cooling 

 saline taste, which leaves a peculiar after-taste. The impure 

 salt evolves ozone slowly. Freshly prepared crystals have no 

 odour, but after a time they emit a peculiar pungent odour quite 

 different from that of ozone, and which appears to be due to 

 persulphuric anhydride. When warmed with concentrated nitric 

 or sulphuric acids the oxygen is liberated largely in the form of 

 ozone. With hydrochloric acid chlorine is evolved. The 

 ammonium salt NH4SO4 has been prepared in a similar 

 manner ; it crystallizes in long prisms and much resembles the 

 potassium salt. The barium salt crystallizes in beautiful large 

 interlocking prisms containing four molecules of water of crystalli- 

 zation. 



The additions to the Zoological Society's Gardens during the 

 past week include a Macaque Monkey {Macactis cynomolgus <J ) 

 from India, presented by Mr. J. Barratt Lennard ; a Rhesus 

 Monkey {Macacus rhesus ? ) from India, presented by Miss 

 Corrie Chisholm ; two Common Marmosets [Hapale jacchus) 

 from South- east Brazil, presented by Mrs. Frederick Betts ; 

 two Bernicle Geese [^Bernicla leucopsis), two Brent Geese 

 (Bernicla brenia), European, presented by Mr. Cecil Smith ; 

 a Gamet {Sula bassana), British, presented by Dr. Davis ; 

 eleven Gold Pheasants {Thaumalea picta i%\ two Amherst 

 Pheasants {Thaumalea amherstice 6 6), two Silver Pheasants 

 {Euplocamus nycthemerus 6 ? ) from China, a Common Pheasant 

 \phasianns colchius <J), British, four Ruddy Sheldrakes (7a</w-«a 

 casarca), European, presented by Mr. Edwin J. Poyser ; a 

 Common Chameleon (Chamcrleon vulgaris) from North Africa, 

 presented by Mr. F. Manners ; a Macaque Monkey (Macacus 

 cynomolgus) from India, deposited. 



OUR ASTRONOMICAL COLUMN. 

 Measurements of Lunar Radiant Heat.— Numerous 

 measurements of lunar radiant heat have been made at Birr 

 Castle Observatory by Lord Rosse and Dr. Copeland, and the 

 results obtained have been published from time to time. During 

 the total lunar eclipse of October 4, 1884, Dr. Otto Boeddicker, 



