March i, 1894] 



NA TURE 



419 



it invariably crystallises out upon cooling in the form o graphite 

 of density about 2 ; but that when the operation is performed 

 under increased pressure the density and hardness of the carbon 

 which eventually separates are augmented, and black diamonds 

 are produced in considerable quantity. A modification of the 

 original form of these pressure experiments is now described, 

 which results in the production of small but perfectly trans- 

 parent and colourless diamonds similar to those found naturally. 

 The former experiments were made with iron and silver as sol- 

 vents for the carbon, the mixture of metal and excess of charcoal 

 being heated in the arc of the electric furnace under pressure 

 until most of the charcoal was dissolved in the white-hot metal, 

 after which the hot crucible was th rown into a tank of water to 

 effect sudden cooling. Bismuth has since been tried as a solvent' 

 but is not found suitable, as a violent explosion is caused when 

 the fused mass is projected into water, probably owing to the 

 sudden decomposition of a carbide of bismuth. Iron is there- 

 fore used, and the cooling is effected by pouring the contents of 

 the crucible into a bath of just melted lead. The solution of 

 carbon in molten iron, being lighter than liquid lead, rises to the 

 surface in spherical globules ; the smaller spheres solidify before 

 reaching the surface of the lead, but the larger ones are still 

 liquid and are still so hot that they cause the lead at the surface 

 to burn in contact with the air, incandescent particles of metal 

 and oxide being projected out, and torrents of fumes of litharge 

 produced. Upon removing the globules floating at the surface 

 of the lead, dissolving their leaden coating in nitric acid, and 

 subsequently removing the iron by suitable solvents, as previously 

 described by M. Moissan, the transparent diamonds are readily 

 jsolated. They frequently exhibit well-defined crystal faces, 

 which are usually curved and striated and etched with cubical 

 markings exactly like those of natural diamonds. They possess 

 the same wonderful limpi dity, high refractive power, hardness, 

 and density (3 '5) as native diamonds, and exhibit many of the 

 properties, such as anomalous polarisation and occasional spon- 

 taneous disruption, owing to their state' of strain resulting from 

 their formation under high pressure, which are characteristic of 

 some Cape diamonds. The hemihedral forms of the cubic 

 system appear to predominate in the crystals examined. They 

 scratch rubies, and resist the action of a mixture of potassium 

 chlorate and fuming nitric acid, but burn in oxygen at a tem- 

 perature of about 900° with formation of pure carbon dioxide. 



Notes from the Marine Biological Station, Plymouth. — 

 During the past fortnight the alga Halosphcera viridis has fre- 

 quently been present in the tow-nettings. The proportion of 

 Mollusc, Polychcete, and Cirrhipede larvae to the res-t of the 

 floating fauna has become still greater. The medusa Phiali- 

 dhim variabile is obtainable in about the same numbers as 

 previously, and a few Obelia medusas have made their first 

 appearance for the year : but, strange to say, Rathkea octo- 

 punctata has not been observed, and even the ephyrse of 

 Aurelia, although numerous in the open Channel, have been 

 scarce within the Sound. No Echinoderm larva; have been yet 

 observed. The Hydroids Tubidaria indivisa, Endendrium 

 ramosiim, and Sertnlaria argentea, and the Molluscs Nassa 

 reticulata, Lamellaria perspiciia and Lamellidoris pttsilla are 

 now breeding. 



The additions to the Zoological Society's Gardens during 

 the past week include two Mozambique yioVLV&^%{Cercopithectis 

 pygerythrusy i S ) from East Africa, presented by Lt.-Gen. 

 Owen L. C. Williams ; a Hooded Crow {Corvus comix) 

 from Norway, presented by Mrs. Wroughton ; a PuSf Adder 

 {Vipera arietans), a Hoary Snake {Coronella cana) from South 

 Africa, presented by Mr. B. Matcham ; a Hairy Porcupine 

 ^Sphingitrus villosus) from Brazil, deposited. 



NO. 1270, VOL. 49] 



OUR ASTRONOMICAL COLUMN. 



A Large Sun spot. — During the foggy days of last week, 

 when the brightness of the sun was not too great to permit 

 direct observation, a sun-spot, which was very plainly visible 

 to the naked eye, attracted general attention. It was first seen 

 in the south-east quadrant on February 19, and will probably 

 pass off the visible disc about March 2. It has been somewhat 

 remarkable for its relatively large penumbra and the scattered 

 character of the umbra ; a very distinct nucleus was also 

 observed. In the course of an interview, Mr. Maunder stated 

 that the spot was at a maximum on February 20, when it was 

 about 48,000 by 46,000 miles, and the area 1870 millions of 

 square miles. It was therefore much smaller than the {jreat 

 spot of February 1892. Though the magnetic disturbances 

 have not been so great as in the case of the 1892 spot, a marked 

 effect on the Greenwich recording magnets was noticed at 3. 15 

 p.m. on February 20, the disturbance lasting about twenty- 

 seven hours. After an interval of about twenty-four hours, 

 another and more intense storm commenced, and reached a 

 maximum at 3 p.m. on February 23. In the case of the spot 

 of February 1892, the violent magnetic storms occurred after 

 the spot had passed the central meridian ; but in the present 

 instance, the disturbances seem to have preceded the central 

 transit of the spot. 



Anderson's Variable in Andromeda. — Prof. E. C. 

 Pickering announces in Astronomische Nachrichten (No. 3213) 

 that an examination by Mrs. M. Heming of photographs taken 

 at the Harvard College Observatory confirms the variability of 

 the star in the constellation Andromeda (K.A. oh. 14m. 48s. 

 Decl. -f26'' 10-3) observed by Dr. Anderson (Nature, Nov. 30, 

 1893). The observations, and those quoted by Dr. Anderson, as 

 having been made at Bonn and Cambridge, indicate that the 

 period of the variable is 281 days, and that the next maximum 

 will occur on March 30. A determination of the form of the 

 light curve led to the interesting result that during the three 

 months following a maximum, the diminution in light is at 

 the uniform rate of one magnitude in twenty-five days ; for the 

 three months preceding the maximum the increase is also uni- 

 form, and at the rate of one magnitude in twenty-six days. 

 Prof. Pickering points out that this great uniformity in the 

 variation in light of the star appears less extraordinary if a 

 similar uniformity in the diminution of the light of Nova 

 Aurigse is considered. From March 7 to March 31, 1892, the 

 light of this star diminished from magnitude 6'3 to I3'3 with 

 almost perfect regularity at the rate of three-tenths of a magni- 

 tude per day. 



Following Prof. Pickering's note is one in which Dr. E. 

 Hartwig gives observations to show that the next maximum of 

 the variable under consideration will occur on March 10, and 

 that the period of variability is 74-4 days. 



A Bright Meteor. — Mr. Andrew Greig writes to us as 

 follows: — "A very bright meteor was seen at Dundee at yh. 

 \%\\n. p.m. on Wednesday, February 21. It was a little to the east 

 of south, and midway between Sirius and Orion's belt. It was 

 falling in a westerly direction, or parallel to a line joining the 

 stars Betelgeux and Rigel. It was visible for about three 

 seconds. There was a slight haze above both southern and 

 northern horizons at the time, but Vega could easily be seen low 

 down in the north. The portion of the sky around Jupiter and 

 the Pleiades was quite clear. ' Streamers' were observed in 

 the north for about three minutes afterwards." 



This meteor was also seen in North Lincolnshire. To an 

 observer in that district it appeared in the north-west by 

 northern part of the sky, and fell in a westerly direction. Among 

 other place? in which the object was observed are Colwyn Bay, 

 Whitby, How den, and Sandal ; but no details as to the path it 

 traversed, or the times of observation, have reached us from these 

 places. An explosion was heard at Colwyn Bay, but no sound 

 is mentioned by other observers. 



THE BAKERIAN LECTURE. 



AN investigation on the internal friction of liquids, carried 

 out by Prof. T. E. Thorpe, F.R.S., and Mr. J. W. 

 Rodger, formed the subject of the Bakerian Lecture delivered 

 at the Royal Society on February 22. The following is an 

 abstract of the communication : — 



The purpose of this paper is to throw light upon the rela- 

 tions between the viscosity of homogeneous liquids and their 

 chemical nature. 



