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SCIENCE-GOSSIP. 



GEOLOGY 





CONDUCTED BY EDWARD A. MARTIN, F.G.S. 



To whom all Notes Articles and material relating to Geology, 



and intended for Science-Gossip, are, in the first instance, to 



be addressed at 69, Bcnsham Manor Road, Thornton Heath. 



Geology in Science-Gossip. — We have pleasure 

 in announcing that the kind offer of Mr. Edward 

 A. Martin, F.G.S. , author of "The Story of a 

 Piece of Coal," etc., to conduct this section of 

 Science-Gossip, has been accepted. 



Geological Records of South-East England. 

 — Mr. H. E. Turner, Bank Street, Ashford, Kent, 

 the Hon. Secretary of the South-Eastern Union of 

 Scientific Societies, has issued particulars of a new 

 section of the Union that has recently been organ- 

 ized for the following objects: (1) To stimulate 

 interest in the observation and recording of geo- 

 logical phenomena ; (2) to form annually a set of 

 lantern-slides dealing with some part of the geology 

 of the south-east of England, and to circulate 

 these, with an explanatory lecture, among the 

 affiliated societies during the winter session ; (3) to 

 form a permanent collection of geological slides 

 and photographs ; (4) to contribute to the national 

 collection of geological photographs now being 

 formed at Jermyn Street Museum under the 

 auspices of the British Association. 



Microlites and Trichites. — The incipient 

 forms of crystallization which are met with in the 

 glassy magma of the vitreous rocks are among the 

 most beautiful of the many forms that the petro- 



FlG. 1. — Thin section of Red Obsidian. 



logist meets with in his microscopical examina- 

 tions. Thin sections of obsidian, when seen under 

 the microscope, become perfectlytransparent, and 



are crowded with minute, transparent, pale-green 

 crystals and short, black, hair-like bodies called 

 trichites (fig. 1). The crystals are in thin rhombic 

 tablets, or irregular grains, sn W n OI an inch in 

 diameter, either scattered about or strung on the 

 short, opaque threads, like conserved cherries on a 

 straw. The larger of these microscopic crystals, 

 known as microlites, is generally a variety of 

 augite, which only appears in microscopic forms 

 in this rock. The trichites are about C000032 

 of an inch wide, and it is these that give the 

 obsidian its black colour. Such microlites and 

 trichites are found in nearly all volcanic glasses, 

 and differ in shape and character according to the 

 condition and composition of the lavas in which 

 they occur. They are rudimentary crystals of 

 minerals which develop in rapidly - solidifying 

 glasses, where a larger and more perfect crystalliza- 

 tion is hindered by the viscosity of the glass. 

 Some of the red obsidians derive their colour from 

 bright red trichites and grains, due probably to 



cv,^!^*- 



Fig. 2. — Microscopic Crystals in Obsidian. 



the higher oxidation of the iron (fig. 2). The 

 coloured ribbons and streaks to which these often 

 give rise produce very grotesque and curious 

 shapes, among which one recognizes the forms of 

 flowers, toad-stools, sea-anemones, jelly-fish, spear- 

 heads and the like, a list only limited by the size 

 of the thin section and the imagination of the 

 observer. 



Underground Fuel. — Few scientific deductions 

 are more striking than the recent one of Lord 

 Kelvin on the world's underground fuel supply, 

 much of which is still hidden. Coal is the residue 

 of ancient vegetation, and the oxygen of the air 

 was probably largely derived from this vegetation, 

 which experiment shows must have furnished three 

 tons of oxygen for each ton of coal. This is the 

 proportion of oxygen consumed in burning coal. 

 The surface of the earth has an area 510 million 

 millions of square metres, each square metre bearing 

 ten tons of air, of which two tons are oxygen, and a 

 simple ' calculation shows with great probable 

 accuracy that the total fuel supply in the world is 340 

 million millions of tons. It was determined, in 1S31 , 

 that England, Scotland and Wales had 146,000 

 millions of tons of coal surely available with 56,000 

 millions of tons more possibly available. This is 

 more than Britain could burn with its own air, 

 having therefore more than an average coal supply. 



The Problem of Diamond Making. — The 

 method proposed by Herr E. Moyat for producing 

 large artificial diamonds consists essentially in 

 sealing pulverized coal, iron chips and liquid 

 carbonic acid in a strong steel tube and submitting 

 them to the action of the electric arc. Unlike 

 other methods, this process generates enormous 

 pressure during the operation of the electric 

 current, and it is believed larger diamonds will 

 crystallize out as the mixture cools. Mr. Hudson 

 Maxim, the celebrated inventor, has also a new 

 process by which it is believed large diamonds 

 may be artificially made. 



