714 



NATURE 



[June 3, 1922 



Thus, the evidence seems to indicate that the Bur- 

 mese amber fauna is Eocene, and older than the 

 Eocene (Bartonian) beds which have produced fossil 

 insects in the south of England. 



At this point, however, a new problem is introduced. 

 A few days ago I received from Mr. Swinhoe a number 

 of beads of extremely pale and pellucid amber con- 

 taining well-preserved insects, all different from those 

 previously described. These insects include a small 

 bee, which seems not to differ at all from the common 

 living Indian Trigona Iceviceps. Smith. The other 

 amber contained no ants, but this includes a worker 

 of Crematogaster, workers of Pheidole, and males of 

 Monomorium. I also find a winged termite, a psyllid, 

 a fly of the genus Phlebotomus, some acalyptrate 

 muscoid flies, a mycetophilid, some small spiders, etc. 

 So far as can be seen, this is a modern series of 

 types. Mr. Swinhoe found that the beads, when he 

 purchased them, had been artificially coloured to 

 enhance their value, and he had this colouring matter 

 removed. He learned that several stained necklaces 

 had been imported from China, so he could not be sure 

 that the material was really from Burma. At one 

 time he even wondered whether the specimens could 

 have been included in artificial amber, as is some- 

 times done. He decided that this last suspicion was 

 unfounded, and I quite agree. His letter ends : 

 " Probably this light amber comes from a locality 

 a few miles off." My own opinion is that this 

 light amber (or copal) is of very recent origin, not 

 earlier than Pleistocene, and contains a fauna which 

 doubtless consists mainly (at least) of species still 

 living. The bee which I recently described as 

 Meliponorytes {?) devictus probably belongs to this 

 material, and not to the Eocene amber. We may 

 surmise that we have the product of some Diptero- 

 carpaceous tree allied to Vateria ; something similar 

 to Miss Ruth Holden's Dipterocarpoxylon burmense, 

 based on fossil wood from Burma. More exact 

 information on this matter is greatly to be desired. 



T. D. A. COCKERELL. 



University of Colorado, May i, 1922. 



Radium Synthesis o£ Carbon Compounds from Air. 



Now that photo-synthesis is attracting special 

 attention it may be interesting to record some recent 

 preliminary experiments on the production of syn- 

 thetic carbon compounds by the action of radium 

 rays on atmospheric air. Under normal conditions 

 of temperature and pressure, it seems evident that 

 this radio - synthesis is capable of producing carbon 

 compounds apart from living cells, and without the 

 agency of solar radiation. 



The experiments arose from an observation, made 

 some nine years ago, during an investigation of the 

 curvature of thin plates of mica when acted upon by 

 radium. After long exposures — some weeks in dura- 

 tion — I noticed a deposit of brown patches, mere 

 specks, on the uppermost side of the thin strips, that 

 is, the side which became concave during a-ray 

 bombardment. 



As this deposit was found not to be responsible for 

 the bending, it was not mentioned in the resulting 

 paper (Journal Rongten Society, No. 44, vol. xi., 

 " Alpha Ray Effect Mechanical "), but left for future 

 investigation, which eventually had to be abandoned 

 on account of urgent war work. 



Having recently made further experiments, I find 

 that the deposits can be detected more quickly, and 

 better observed, by using freshly drawn fibres of 

 quartz or glass, diameter about 0-04 millimetres. 

 Several of these may be spaced about i mm. apart, 

 supported on a framework immediately over the 



NO. 2744, VOL. 109] 



radium salt, about one-eighth of an inch above the 

 uncovered radio-active surface (one or two milli- 

 grammes of radium or mesothorium is sufficient). 



The whole arrangement should be put into a clean 

 cardboard box (about one litre capacity, to reduce 

 convection currents), with loose fitting lid, which is 

 then put away in a dark room. After remaining un- 

 disturbed for a week, it will be seen, using a Codding- 

 ton lens (or better if transferred to a microscope with 

 one-inch objective), that the fibres are covered with 

 a clear white viscid liquid film, which is beginning to 

 gather up into beads, or droplets, at more or less 

 regular distances. After a further exposure of a few 

 days, it will be found that all the droplets have 

 increased in size, some having reached a pale sherry 

 colour. Further exposure leads to increase in size, 

 eventually resulting in dimensions about double the 

 diameter of the fibre. The colour changes may be 

 from white to sherry, red, then dark brown, after 

 about six weeks' exposure ; later a little irregularity 

 of contour 'of the brown droplets may be noticed, 

 showing that the liquid is tending to solidify with 

 irregular contraction ; fresh deposits may appear in 

 the interspace between old droplets, so that a fibre 

 may contain droplets in all stages. 



It is evident that the first liquid product, colourless 

 at the beginning, is soon oxidised in the ozone which 

 is produced by the a-rays. By reason of the time 

 required and the minute quantity of the first product, 

 it is difficult to make tests before oxidation has taken 

 place to some extent. 



Preliminary microscopical examination of the final 

 dark brown product, which becomes a strongly ad- 

 herent scaly deposit, on a mica strip (after nine years) , 

 demonstrated that the brown deposit was insoluble 

 in alcohol and chloroform but dissolved in hot water. 

 On evaporation of this solution a brown film was 

 formed which cracked into scales on drying. This 

 film became carbonised on heating, at about the same 

 temperature as a particle of gum acacia, on the same 

 electric hot-plate. 



So far, I have not obtained deposits by using a- /3- 

 or 7-rays, either separately or in combination. The 

 gaseous emanation of radium seems to be necessary, 

 which points to the probability that the radium pro- 

 ducts of short period are chiefly concerned in the 

 synthesis, or in facilitating condensation on solids. 

 On this point, and on the physical aspects, further 

 experiments are in progress, but it is very desirable 

 that the chemical examination of the products should 

 be made by others with better facilities than those 

 I possess for dealing with very minute quantities. 

 Possibly increased production may be obtained by 

 increasing the proportion of water yapour and carbon 

 dioxide in the air. I should be very glad to know of 

 any work already done bearing on the subject. Have 

 such products ever been found in the atmosphere ? If 

 ultra microscopical, rain may contain some. 



F. Harrison Glew. • 



156 Clapham Road, London, S.W.9. 



Cephalic Index and Sex. 



In Nature of March 23, p. 389, I find the state- 

 ment — in a sum_mary of a paper by Miss R. M. Fleming 

 — that " British women show more development of 

 pigment, brachycephaly, and prognathism than do 

 men." 



As to the cephalic index I see quite the same in 

 Arthur Thomson and Randall-Maclver's interesting 

 account of skulls from " The Ancient Races of the 

 Thebaid " (Oxford, 1905) ; and probably this " more 

 development of brachycephaly " in women is a general 

 law. 



