Mineralogy and Geology, 143 



Hobson considers the new acid as formed by the replacement of one 



equivalent of oxygen in three of sulphurous acid by one of ethyl. The 



I acid yields colorless and crystalline salts with various bases. Sulphurous 



t acid forms a similar compound "vvith zinc-methyl, and doubtless there 



exists a series of thionic acids homologous with that described by Hobson. 

 Quarterly Journal of the Chemical Society^ April, 1857, 55, w. G-- 



8. J^ote on Ritchieh improved Ruhmhorff'^s Apparatus ; by the author. 

 Siuce writiijg my paper (p. 45) I have constructed a helix in which the 



plane of the strata of wires is perpendicular to the tube, insulated as be- 

 fore. With one of the same length of wire as the largest one before men- 

 tioned, — throwing a spark, with six cells, sis inches, — I have used a battery 

 of eighteen cells, (Bunsen's) ; but by using a battery of three series of six 

 cells (that is, an intensity of six, and quantity of three), a yerj volumin- 

 ous spark was obtained; as the action soon became feeble, I took the 

 secondary coil from the glass cylinder and found that the current had 

 passed through the ylass near each end of the coil, forming a circuit 

 through the primary wire ; two minute holes, of a hair's breadth, from 

 one-tenth to one-eighth inch diameter, were drilled through, but the glass 

 was not fractured ; it also passed through several thicknesses of vi 

 ized rubber. The helix was uninjured, proving the insulation obtained 

 by the mode o{ winding it. A more perfect insulation between the helices 

 is readily made ; and I now use a tube of gutta percha over the glass. 

 With powerful batteries the condenser of varnished paper is not sufficient, 

 as the current passes entirely through, and with such I use oiled silk. I 

 have put several condensers in the same instrument, connecting each by 

 turning a screw, so that either or all can be used. Varied and beautiful 

 effects are produced, particularly in vacuo, by using different amounts of 

 suiface of condenser. 



Boston, June 10th, 1857. 



9, Silica and Alumina in the ashes of Lycopodium, — The ashes of 

 three Lycopodiums afforded F. H. Grafen (Ann. CL Pharm. C, 207), the 

 following results : 



Silica. Alumiaa- 



1. Lycopodium chami^cyparissus, 13 54 



2- L. clavatum, 14 27 



3. L, denticulatum, - - - - 42 2 



II. MINERALOGY AJSTD GEOLOGY. 



1. Supplement to the Fifth Edition of a Manual of Elementary Ge- 

 ology ; by Sir Charles Lyell. 2d edition revised. 38 pp., 8vo. Lon- 

 don : 1857. — This supplement contains chapters on the following topics: 



(1.) British Pliocene strata, — including observations on change of cli- 

 mate in Uie pliocene epoch, — on fossil mammalia in the Thames valley 

 on the fossil musk-buffalo in the drift near London and near Berlin. 



(2.) AYherc to draw the line between the Miocene and Eocene ; in which 

 the Nebraska tertiary is arranged in the lower miocene. 



(3.) Miocene Fauna of the Sewalik Hills. 



(4.^ Denudation of the Wealdon. 



(5.) New Fossil Mammalia from the Purbeck or Upper Oolitic strata 

 in Dorsetshire. 



4l 

 J 



+ ' 



