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HA RD IVICKE'S SCIENCE- G OS SIP. 



The Dover Field Club held a most successful 

 conversazione at the Town Hall on November 3rd, 

 which aroused much public attention. The Society- 

 has also commenced a series of public lectures on 

 popular science, the first of which was delivered by 

 J. E. Taylor, F.G.S., Editor of Science-Gossip, on 

 November 24th. Subject : " Earthquakes and Vol- 

 canoes." 



Dr. Taylor also lectured, during November, 

 before the Winchester College Natural History 

 Society, on November 3rd, subject: "The Story 

 of a Flint Pebble " ; at the Chelmsford Museum, 

 November loth, on " Fossils " ; at Saffron Walden, 

 on "Microscopical Animals" (November 8th); at 

 Alton, on "Flowers"; at Hadleigh, on "Flowers 

 and Fruits"; at Halesworth, on "The Great Ice 

 Age," &c. 



Mr. R. Miller Christy, F.L.S., is about to 

 publish a work on the Origin and Meanings of the 

 Public House, and other signs found in the county of 

 Essex. 



The Croydon Microscopical and Natural History 

 Club held a very successful soiree on Wednesday, 

 November 17th. 



The Forest Hill Scientific and Microscopical 

 •Society have introduced a series of "Science 

 Gossip " nights into their winter nights' programme. 



We have received No. 75 of Mr. William Wesley's 

 useful Natural and Scientific Book Circular. 



A "Potato Conference" is to be held on the 

 2nd and 3rd of December. 



We have received from Mr. H. Vial, of Crediton, 

 some of his newly-brought-out slides of pathological 

 and botanical preparations. They are remarkable 

 for their neatness, as well as for their scientific 

 usefulness. 



MICROSCOPY. 



Pyritised Diatoms.— Dr. Julien writes as follows 

 in the " New York Microscopical Society's Journal " : 

 " I think you will agree with me, on an examination 

 of several preparations of these diatoms, that the 

 following points of mineraloyical interest are esta- 

 blished : — First, that the material referred to by all 

 writers under the broad name of pyrites, consists 

 substantially of the single mineral pyrite. To deter- 

 mine this point, I searched for minute cavities in 

 which the substance might have found opportunity 

 to crystallise, and discovered not only minute drusy 

 surfaces, but also little spherules covered by pro- 

 jecting crystals. The globules which Mr. Kitton 

 detected, appear to have been round and smooth, 

 probably concretionary. On those exhibited may be 



seen triangular faces, which appear to belong to 

 octahedra ; these crystals must therefore consist of 

 pyrite. This conclusion will be confirmed by a 

 glance at the slide on which is mounted a crystalline 

 crust from a specimen of fossil fruit, converted into 

 pyrites from the London clay at thelsle of Sheppey. 

 This drusy surface shows distinct, sharp octahedra 

 of larger size, so that this crystalline form probably 

 prevails in the pyrite crystals throughout the London 

 clay. Second. The true colour of the pyrite films, 

 when examined on a fresh cross fracture, appears to 

 be a grayish-white. This indicates that the crystals 

 are far from pure, probably mixed with a large pro- 

 portion of marcasite. Third. The incipient decom- 

 position of the mineral is characteristic of the presence 

 of marcasite, beginning with a golden yellow tarnish 

 within, and assuming a bronze colour without. As 

 the decay progresses, the valves become covered by a 

 reddish' film of iron oxide, and finally, the entire 

 material passes into reddish-brown iron-ochre, some- 

 times blackened as if by the intermixture of oxide of 

 manganese. The mode of deep subterranean decom- 

 position is, therefore, hepatic, and vitriolescence is 

 never observed in these altered diatoms ; although 

 the latter form of decay attacks the nodules of pyrites 

 lying nearer the surface in the London clay, at other 

 points along the Thames, as at the Isle of Sheppey. 

 In conclusion, I may state that I have found in the 

 study of pyrites, many rich and interesting fields of 

 investigation in which the testimony of microscopical 

 observation has proved indispensable." 



To Sharpen Razors for Section Cutting. — 

 In the "Scientific Enquirer," Mr. V. A. Latham 

 says : — " The simplest method of sharpening a razor 

 is to put it for half an hour in water, to which has 

 been added one-twentieth of its weight of (H CI) 

 hydrochloric acid, and water (which is muriatic acid), 

 or sulphuric acid, then lightly wipe after a few hours ; 

 set it on a hone. The acid here supplies the place of 

 a whetstone, by corroding the whole surface uni- 

 formly, so that nothing further than a good polish is 

 necessary. " The process never injures good blades, 

 while badly hardened ones are frequently improved 

 by it." 



ZOOLOGY. 



The Extirpation of Lepidoptera. — The more 

 striking species of lepidoptera seem doomed to a 

 speedy extinction, as far as Britain is concerned. As 

 lately as three years ago the six-spot burnet {Zygaena 

 filipendulm) was fairly common in the neighbourhood 

 of Edmonton. Now, prolonged and repeated search 

 is needed to espy a solitary specimen. Before the 

 operations of the so-called "conservators " of Epping 

 Forest began, Euchelia Jacobite was to be met with 

 in a low, moist part of the forest, not very far from 



