Chemistry and Physics. 251 



mixed with fire damp. The apparatus employed by Thorpe con- 

 sists of a narrow box of wood 12 feet long and 5 inches square 

 intersected at its middle point by a second similar box 6 ft. long. 

 Both boxes are open at the ends and are provided with lids 

 attached with strong hinges and hasps. They are made of inch 

 oak and are put together with screws. At one end of the long 

 box is a slide ; and the end itself fits into a quadrangular box 9 

 inches square, furnished with a lid on top and a small hole for 

 the introduction of a tube carrying s;as. On delivering into the 

 box such an amount of gas as will make an explosive mixture 

 (best from a graduated bell-jar over water) and on strewing coal 

 dust along the entire length of the boxes, a blank cartridge, fired 

 from a pistol through the lid of the box to illustrate the effect of 

 a blast, raised a dust cloud which ignited by the explosion, projects 

 a flame several feet long from the farther end of the box. To 

 illustrate a local explosion of fire damp, the slide at the end of 

 the box is pushed in and an explosive mixture is made in the box 

 beyond it. The slide is then withdrawn and a match applied. 

 The explosion raises a clo*ud of dust and this by its violent igni- 

 tion produces a continuous cloud along the whole length of the 

 box which is driven out four or five feet from the remote end. 

 Little heaps of gunpowder, or pieces of touch paper placed at 

 intervals along the box, are rarely fired. — J. Chem. Soc, lxi, 414, 

 May, 1892. G. f. b. 



2. On certain JVew forms of Carbon. — A new variety of car- 

 bon has been obtained by Luzi. When a piece of porcelain, such 

 as a crucible or crucible-cover, is heated in a blast furnace to the 

 highest attainable temperature, say to 17*70° C, the fusing point of 

 platinum, and then the access of air is cut off, the highly heated 

 porcelain is surrounded by a smoky flame, which is allowed to act 

 upon it for ten or fifteen minutes. On removing the piece of 

 porcelain from the furnace, it is found to be covered with a 

 peculiar deposit of carbon. If it was unglazed, the deposited 

 carbon resembles graphite; but if glazed, the deposit is bright 

 and silvery and has a metallic luster, resembling closely a silvered 

 mirror. Portions of the deposit adhere so firmly that they can 

 be polished with a cloth ; others separate in the form of mirror- 

 like facets of high luster. Loose portions can be pulled off; and 

 then they curl up into rolls like metal shavings. They are ex- 

 ceedingly light and stick to the fingers like silver leaf. This form 

 of carbon is free from ash and does not contain hydrogen; nor 

 does it give the nitric acid reaction for graphite. Moreover it is 

 absolutely opaque. The author has also examined 17 additional 

 varieties of natural graphite by his nitric acid reaction. Nine of 

 these give the reaction and are therefore graphite proper ; eight 

 do not and are therefore included in the second class which he 

 calls graphitite. Of the 31 specimens thus far examined 16 were 

 graphite and 15 graphitite. The blackish-gray substance into 

 which diamond is converted on heating, and which resembles 

 graphite, did not give the nitric acid reaction. — Ber. Berl. Chem. 

 Ges. xxv, 214, February, 1892. g. f. b. 



