90 



NATURE 



[March 23, 19 16 



of avoidable trouble in electric furnace work. The 

 furnace shown in operation at the meeting consumed 

 100 amperes at lo volts when running at 2000° C. 

 This temperature was attainable in two or three 

 minutes. A home-made transformer with about 100 

 primary turns wound in two halves and three separate 

 secondary coils that can be connected in series or 

 parallel enables the furnace to be run off almost any 

 ordinary lighting circuit. 



Mr. R. S. Whipple, among other speakers, testified 

 to the value and convenience of this simple form of 

 carbon tube furnace. It was stated that Northrup in 

 America was using a similar furnace on a larger scale 

 for gear hardening in a motor-car factory. A thermo- 

 <x)uple is attached to each piece of gear and the tem- 

 perature is run up until the hump on the curve shows 

 the recalescent point to have passed. The gear is 

 then removed and quenched. One of the furnaces 

 exhibited by Dr. Harker was made for a steel foundry 

 at Sheffield for standardising optical pyrometers, of 

 which a very large number were stated to be in use. 



The discussion emphasised the fact that the great 

 desideratum at the present moment for many require- 

 ments, both in the laboratory • and the works, is a 

 furnace that will have all the advantages of the carbon 

 tube furnace, but which will not evolve carbon com- 

 pounds. Dr. Rosenhain had used a vacuum furnace 

 wound with tungsten wire for melting pure iron 

 (meking point 1525 + 5° C), but the tungsten became 

 brittle after heating, and was soon useless. A resist- 

 ance furnace using granular tungsten working in 

 liydrogen or nitrogen was suggested as one substitute, 

 and another was a carbon tube furnace with an inner 

 tube and an indifferent gas between the two. It 

 appears, however, that zirconia tubes are being experi- 

 mented with, and a successful outcome of this work 

 IS hopefully anticipated. Zirconia is one of the best 

 refractories known, and if it can be obtained pure in 

 granular form almost any temperature will be possible 

 with surface combustion. Dr. Rosenhain made the 

 useful suggestion to coat carbon electrodes or tubes — 

 even in ordinary commercial electric furnaces — with 

 metallic copper, iron, or aluminium by means of the 

 Schoop spray process, as a means of ensuring good 

 electrical contacts. 



For temperatures up to 1000 or 1200° C, tube or 

 muflfle furnaces heated with nickel-chromium wire 

 were recommended by several speakers, some of whom 

 "have abandoned gas-heating altogether for tempera- 

 tures below 1000°. On the other hand, some of the 

 modern gas burners, of which several types were 

 described, appear to give excellent results at high 

 temperatures. Air under high pressure is essential, 

 and so It appears is. violent mixing of the air and gas 

 — the cause of the great noise made by these furnaces. 

 Mr. S. N. Brayshaw described the ingenious burner 

 which bears his name, which Is displacing the oxy- 

 Tnydrogen flame, too local in Its heating, for melting 

 platinum. For many experimental metallurgical pur- 

 poses the Richmond gas furnace was recommended. 



INSECTS IN AFRICA AND THE EAST. 

 N accurate description of the Indian lac insect 

 {Tachardia lacea), founded on new observations 

 of its life-history and habits, has long been wanted by 

 students of economic entomology. They now find this 

 provided in the recently issued Indian Forest Memoir 

 (Zoology, vol. ill., part 1) by Dr. A. D. Imms and 

 Mr. N. C. Chatterjee. The various stages are illus- 

 trated by beautifully executed coloured figures, and 

 there are enumerations of the insect's food-plants and 

 analyses of its important secretion. A remarkable 

 feature Is the dimorphism shown in the male, which 

 may be either winged or wingless — the latter condition 



NO. 2421, VOL. 97] 



A' 



very rare among Coccidae. The Tachardia is attacked 

 by an alarming array of enemies, of which the cater- 

 pillar of a noctuid moth, Eublemma amabilis, is the 

 most formidable. It is aided in its destructive efforts 

 by several other caterpillars of Lepidoptera, a large 

 number of beetles and their larvae, and a host of 

 hymenopterous parasites. 



To the December part (3) of the Bulletin of Entomo- 

 logical Research (vol. vi.) Dr. J. W. Scott Macfie 

 contributes observations on the bionomics of Stego- 

 myia fasciata, the mosquito that is well known as the 

 alternate host with man of the yellow fever parasite. 

 The female insect pairs soon after emergence, and 

 then must have a meal of blood before laying her eggs. 

 Fertile eggs may continue to be laid for thirty-seven 

 days without necessity for a second pairing. The 

 prevalent belief that this mosquito sucks blood by 

 night only is not confirmed, "but sometimes she re- 

 fuses an offer to feed in daylight in favour of the next 

 opportunity to feed in the dark." The m.ale's taste 

 is gentler, as his staple food is honey. 



The same part of the Bulletin contains also notes, by. 

 Dr. W. A. Lamborn, on the habits of Glossina morsi- 

 tans — the tsetse-fly that carries sleeping-sickness 

 trypanosomes in Nyasaland. The insects are 

 by no means confined to the mapped " fly- 

 belts." The preponderance In number of males 

 among flies captured on the wing, which con- 

 trasts with the close equality of the sexes as bred 

 from puparia, is explained by the author as due to the 

 male's habit of pairing as the result of violent capture 

 rather than of courtship; hence the females shun the 

 society of the opposite sex. The slimy secretion of the 

 Glossina larva is believed by Dr. Lamborn to afford 

 some protection against the attacks of certain ants. 

 Puparia are rarely found parasitised by larvae of 

 MutlUa and other Hymenoptera, and the adult tsetses 

 are sometimes caught and devoured by dragonflies. 

 Dr. Lamborn described how a dragonfly, Orthetruvi 

 chrysostigtna, hovered around his party of six "boys," 

 swooping down and picking off a tsetse from the back 

 of one who stooped to drink at a pool. ^ Many speci- 

 mens of the Orthetrum were captured In the act of 

 devouring tsetses, which appear to be equally accept- 

 able, whether fasting or' filled with freshly-ingested 

 blood, and this species of dragonfly is evidently very 

 expert in catching Glossina. Another kind of dragon- 

 fly (Crocothemis erythraea), on the other hand, handled 

 a tsetse so clumsily as to convince Dr. Lamborn that 

 it is a novice with this special type of prey. A 

 description with figures of several species of chalcids 

 which Dr. Lamborn has reared from the Glossina 

 puparia Is given by Mr. J. Waterston (t.c. part 4). 



An addition to our knowledge of the distribution of 

 tsetses Is contained in Dr. Schwelz's paper In the third 

 part of the bulletin ; he has traced G. morsiians In the 

 Katanga district of the Belgian Congo far to the west 

 of the great river. Dr. Schwetz writes also on 

 the range and habits of G. brevipalpis — a fly often 

 overlooked as It flies before sunrise and after sunset. 



G. H. C. 



INTERESTING FORAMINIFERA. 



IN a fine memoir ^ on Foraminlfera from the 

 Kerimba Archipelago, Portuguese East Africa, 

 Messrs. Edward Heron-Allen and Arthur Earland deal 

 with no fewer than 470 species and varieties, of \yhlch 

 thirty-two are new to science. There is a striking 

 resemblance between the general fades of the gather- 

 ings at Kerimba and that of the late Mr. F VV. 

 Millett's collection from the Malay Archipelago. The 



1 Trans. Zoological Society of London xx (1914), pp. s^.-^-po, 3 pis. ; and 

 /Sid., XX. (iQii), pp. 543-794, »4 pls., 3 H^ ^" "''•f" ^^°^- Zoological 

 Society of London, 1915, pp. 295-8. 



