312 



NATURE 



[May 12, 1910 



the undoubted sexes of Meroglossa parallela (Ckll.), a 

 metallic insect related to the type of Palaeorhiza, and these | 

 showed exactly the same thing. I then looked at a new 

 species {Palaeorhiza or Meroglossa melanura), with a 

 honey-coloured abdomen black at apex, the mesothorax 

 striped with 3^ellow and black, and the base of the meta- 

 thorax finely longitudinally fluted. In this the sexes were 

 associated without a doubt, and the difference in the 

 tongues was as in the others. Still others were examined, 

 all with the same result. It appears that the female in 

 this genus lacks, or fails to develop, the determiner which 

 represents the pointed apex of the tongue. Another 

 peculiar character, a comb on the first two joints of the 

 maxillar}' palpi, is common to both sexes of Meroglossa. 



Another generic name for Australian bees must fall. 

 The study of additional material shows that my Proso- 

 pisteron is not valid ; its type-species must be known as 

 Prosopis serotinella. 



The extraordinary Pachyprosopis mirabilis of Perkins, 

 described from N. Queensland, without further data, was 

 taken by Mr. Turner at Mackay in May, 1900. 



T. D. A. COCKERELL. 



University of Colorado, Boulder, Colorado, U.S.A., 

 April 21. 



Fluorescent Absorption. 



In Nature of January 6 Mr. Burke criticises the con- 

 clusions which I drew from my experiments proving that 

 fluorescent absorption does not exist (Phil. Mag., 1909). 



The method which I devised was a direct one, and free 

 from all sources of error. I cannot see any point in Mr. 

 Burke's criticism; I used a scheme for making the source 

 of light and the fluorescing absorbing cell intermittent, 

 throwing the flashes either " out-of-step " or " in-step " 

 at will. If the flashes were out-of-step, the light from 

 the source traversed the absorbing cell while it was not 

 .fluorescing. This flash entered the eye, and waf immedi- 

 ately followed by the flash of fluorescent light from the 

 cell, the source being in darkness during its emission. 

 The total amount of light, or the sum of the two sets of 

 .flashes, was the same whether they were "in-step" or 

 "out-of-step," show/'ing that the absorbing power of the 

 cell was not increased by its fluorescence. Mr. Burke now 

 appears to stand alone as a champion of fluorescent absorp- 

 tion, for Nichols and Merritt have recently repeated their 

 work with improved apparatus and methods (one of them 

 being a modification of my stroboscopic method), and have 

 failed to find any trace of the phenomenon. 



R. W. Wood. 



Johns Hopkins University, April 28. 



Centre of Gravity of Annual Rainfall. 



Mr. Watt's nil admirari attitude towards the C.G. of 

 annual rainfall is unfortunate, for, notwithstanding his 

 disclaimer in the first sentence, I find that his statement 

 in the last sentence of his letter irf Nature of April 28 

 is another a priori shot ! In the Mysore rainfall annual 

 reports of the last fifteen years I have given diagrams of 

 the monthly rainfall of the eight districts as percentages 

 of the yearly totals, but they are not simple, or similar, 

 or symmetrical. Yet year after year there is a close 

 agreement in the C.G., or date round which each year's 

 rainfall balances. Verb, sat, sap. 



J. Cook. 



30 Hermitage Gardens, Edinburgh, May 3. 



Impure Manganese Di-oxide. 



A FEW weeks ago I had occasion to order a quantity 

 of manganese di-oxide for general lecture and laboratory 

 experiments, and we duly received the same from a well- 

 known firm the name of which it would be invidious to 

 mention. Although in colour the manganese di-oxide was 

 normal, we soon found that its chemical properties were 

 very erratic. When mixed with potassium chlorate and 

 heated gently, the mass inflamed inside the flask, and a 

 reaction proceeded with explosive violence, resulting in the 

 formation of clouds of smoky gas relatively poor in oxygen. 



NO. 21 15, VOL. 83] 



When warmed with concentrated hydrochloric acid the 

 action was unusually vigorous, and an inferior grade of 

 chlorine was evolved possessed of a curious odour re^ 

 sembling that of euchlorine. The black colour of the 

 powder rapidly disappeared, yielding a yellow solution, ani 

 a white, insoluble residue, which, from its voluminoirt 

 appearance, suggested silica. 



One of my senior students, Mr. William Davison, there- 

 upon analysed the di-oxide, and obtained the following 

 results : — 



Manganese di-oxide 



Antimonious oxide 

 Silica 



Ferric oxide 



Arsenious oxide ... 



Sulphur ... ... ... ... ,.. 



Moisture 



99-95 

 That this was a case of wilful adulteration I do nQt 

 suppose for a moment ; but it seems desirable to direct the 

 attention of teachers and others to the possibility of such 

 a common and cheap article as manganese di-oxide being 

 sold, not only in an impure form, but in one which it is 

 positively, dangerous to use with potassium chlorate for 

 such a simple and universal experiment as the preparation 

 of oxygen. J. Newton Friend. 



The Technical College, Darlington, May 6. 



BRITISH NEW GUINEA. 



COLONEL MACKAY was chairman of a Royal 

 Commission appointed to proceed from Australia 

 to inquire into the present conditions of the territory 

 now knowi> as British New Guinea. As such, he 

 proceeded along the south coast of the island to its 

 eastern extremity, then visited the D 'Entrecasteauk 

 and other groups in the offing, subsequently proceed- 

 ing along the north coast to^ Buna Bay. Here he 

 left the sea and struck inland to visit the Yodda 

 Goldfield, returning overland to Port Moresby. This 

 was the most arduous and interesting part of hjs 

 journey, for the Owen Stanley Mountains, which here 

 reach about 7000 feet, had to be crossed. Apparently 

 the range really consisted of a^ series of more or 

 less parallel ridges, up and down which the party was 

 scrambling for seventeen days, camping during much 

 of the time in tropical rain forest. 



It is the record of the above trip which "Across 

 Papua " presents to us in pleasantly written form. 

 The expedition was not in any way a scientific one, 

 but the author shows that he has considerable powers 

 of observation. He notes " the absence of stone on 

 the higher ridges, and the extreme narrowness of 

 their root-strewn, moss-carpeted crests. How also, as 

 we approached the higher altitudes, lichen and moss 

 gradually enveloped the timber until they covered 

 limbs and leaves alike ; but what impressed me most 

 was the serene calm that reigned over all, for I heard 

 no crash of fierce or fearful animal, no sound of 

 human voice, no song of radiant bird in all that 

 kingdom of mist and sunshine, of sparkling dew- 

 gems, and immemorial silence." 



The truth of this traveller's description we know 

 well, but what wealth it suggests to the tropical 

 naturalist — the enormous variety of plants which 

 make up such a forest, each with its peculiar insects, 

 many lizards and frogs showing quite peculiar adapta- 

 tions to their damp environment, peculiar land shells 

 on every ridge. The natives live on the lower slopes, 

 but seem to be less cannibal and of better stock than 



1 " Across Papua." Being an Account of a Voyage Round, and a March 

 Across, the Territory of Papua with the Royal Commission. By Colonel 

 Kenneth Mackay, C.B. Pp. xvi + 192. (London: Witherby and Co.) 

 Price 7s. 6d. net. 



