i8 



HA RD WICKE'S SCIENCE- G OSSIF. 



purpose best, as it is tough, and fairly homogeneous 

 in structure. Each leaf is first separately examined 

 by polarised light to detect any flaws or holes, the 

 smallest pin-hole rendering the leaf practically useless. 

 It is then soaked in vinegar for twenty-four hours in 

 order to neutralise the alkali in the fibre, and, after 

 thorough washing, is ready for the next process. It 

 is now laid out flat in a solution of mercury bromide ; 

 a rod of specially-prepared shellac is then taken, and, 

 after being raised to a high potential condition by 

 treatment with a silk exciter, it is put into contact 

 with the mercury solution. By this means the leaf is 

 gradually electrolised, the potassium and sodium in 

 the fibre combining with the mercury to form a 

 coating of amalgam. In this state the leaf is a capital 

 conductor, and the inventors have even succeeded in 

 using it as a substitute for lead in secondary batteries. 

 A heavy current is now passed through it so as to 

 carbonise the vegetable fibre, the current being 

 increased till every trace of amalgam is volatalised. 

 It is then cut into filaments, and each is forced 

 through a draw plate. As it is not of sufficient 

 "resistance," resort has to be had to a process 

 called " flashing." The consists in passing a mixture 

 of ammonia and hydrogen gases over it while it is 

 heated by the electric current. The resistance 

 rapidly rises, and at the proper point the current is 

 automatically cut off by an ingenious switch arrange- 

 ment. The filament is now bent into horse-shoe 

 form, and is ready to seal into the bulb. Perhaps 

 the most important discovery made by Messrs. Swin- 

 burne, is the enormous increase in light that can be 

 obtained for a given current by employing an atmos- 

 phere of slightly compressed oxygen in place of the 

 complete vacuum hitherto customary ; and though by 

 this means the life of the lamp may be slightly 

 shortened, it is not considered important in view of 

 the great gain in light. If this process, beautifully 

 simple as a laboratory experiment, should prove 

 commercially successful, large quantities of picked 

 and selected leaf will be required, and Messrs. Swin- 

 burne contemplate inviting tenders from some of the 

 leading growers in the county. The bulk of the 

 plant has been already erected, and Messrs. Cromp- 

 ton & Co., of Chelmsford, who are working overtime, 

 have got the machinery well in hand, and hope to 

 complete delivery by the 24th inst. 



MICROSCOPY. 



"Journal of Microscopy."— (Edited by Alfred 

 Allen.) The last number of this well-known journal 

 contains the following papers, besides a host of notes, 

 notices, &c. : — " The Air-bladder of Fishes considered 

 as a Degenerate Lung," by Mrs. Alice Boddington ; 

 " Development of the Tadpole," by J. W. Gate- 

 house ; "Fogs," by Beatrice Taylor; "Economic 

 Entomology," by James A. Forster ; " On the Male 



Generative Organs of Two Species of Cypris (C 

 Cina-a and C. tninuta)" by T. B. Rosseter ; " Pseudo- 

 Helminths," by Jabez Hogg ; " The l^Iicroscope and, 

 How to use it," by V. A. Lalham. 



Another Evening with the Eoyal Micro- 

 scopical Society. — The Microscopical Society may 

 congratulate themselves upon the success with which 

 their "scientific evening," held in the library of 

 King's College, on the aSth of November, passed off, 

 in spite of the unpropitious weather. The principal 

 item of novelty was the display, on a screen, in front 

 of the o.\y-hydrogen lantern, in a darkened room 

 adjoining, of numerous negatives of microscopic 

 objects photographed from the originals direct : — 

 diatoms, bacilli, insect preparations, pathological 

 specimens and botanical sections, all furnished illus- 

 trations of how soon, and how well. Dr. Crookshank's 

 suggestions and example, at a former "scientific 

 evening," had been followed up by Mr. A. Pringle 

 and Mr. Charles Lees Curtis, who both deserve great 

 credit. This display was the finest of the kind that 

 I have ever seen or heard of. Only fancy ! the 

 image of half a frustule of Amphipleiira pellucida was 

 thrown on to the screen, so as to appear three feet 

 long, or more, with the markings as distinctly 

 shown as the bars of a Venetian window-blind. I 

 should guess the magnification at not less than. 

 20,000 diameters. Has anything been done like this 

 before ? I think not. I could mention many other 

 objects they showed in rapid succession equally 

 well ; but the naming of this one, so admirably 

 displayed, gives an idea of the advanced stage of 

 micro-photography these gentlemen have reached. In 

 the library, very many curious things were to be- 

 seen. There was a fine specimen of Braula ccccUy 

 the rare parasite of the hive bee (something like a. 

 small sheep tick), shown by Mr. Mainland. He 

 referred me to an article in SciENCE-GossiP (May 

 188 1), by Mr. Fedarb, on Braula ; and I have looked 

 it up, with pleasure ; but I think Mr. Mainland 

 might perhaps have something more to say about the 

 insect, if he tried. Then there were numerous clever 

 dissections of insects, one in particular, by Mr. Fitcli 

 (of the golden-banded fly), was universally admired, 

 Mr. Rousselet had a new rotifer ; Liuiiiias Cormiella. 

 There were also other exhibits of rotifers, &c., 

 by several gentlemen. Eye sections were numerous, 

 of moth, spider, tadpole, and lamprey (pineal eye), 

 Mr. Beck showed Aniphiplcura pellucida, and the 

 cyclosis in Vallisneria. Messrs. Watson had an 

 excellent display of fine pathological specimens ; and 

 a grand slide of arranged diatoms, butterfly scales, 

 &c. Mr. R. T. Lewis had a drawing of the rare 

 coccid, Lccamiuiii acnminatioii, from Biitish Guiana, 

 but his most interesting contribution was a number of 

 unknown larva-, from Natal, alive. They appeared 

 to be lepidopterous, and were remarkable from the 

 fact that they had constructed portable houses for 



