SCJEXTiriC SUMMAEY. 
257 
The latter, to which is attached a firm horizontal bar, mto which the lenses 
are screwed, is elevated and depressed by a rack-and-pinion movement, 
the milled head beino; situate at a level a little below that of the stage. In 
the centre of the foot is placed the mirror, which moves in an arc of brass, 
that in its turn works upon a pivot in the foot of the instrument. This 
microscope, with three lenses and mahogany case, is (we understand) sold 
at the moderate price of thirty-five shillings. 
BIKER’S DISSECTING MICROSCOPE 
MINERALOGY. 
Very little has been added to our knoAvledge of this subject during the 
past quarter. A good deal has been achieved in the shape of compilation, 
and under this category we would class Professor Sterry Hunt’s memoir on 
“ Contributions to Lithology,” in the new Series of the Canadian Naturalist 
and Geologist The follo’sviug accoimt, however, of a new mineral, may in- 
terest our readers. 
Tasmanite, a Neio Mineral of Organic Origin. — This mineral is described 
by Professor Church in the Philosophical Magazine, for December, and in 
the Chemical News, of December 10, and from the latter we take the descrip- 
tion of the new compound. It occurs in laminated shale, near the river 
Mersey, north side of Australia. The shale contains from 30 to 40 per cent, 
of a yellowish brown combustible matter, which occurs in small disks marked 
with a few ridges. These disks may be separated from the inorganic portion of 
the mineral by crushing it to coarse powder and pourmg strong hycb’ochloric 
acid over it, when the disks become liberated, and float to the surface of the 
liquid, the density of which should have been increased by the addition of 
chloride of calcium to it. The density of the disks is about 1*18; hardness, 
2 ; fracture conchoidal ; and lustre resinous. They are unaffected by hydro- 
chloric acid, uncarbonized by sulphmic acid, and slowly dissolved by nitric 
acid. They are insoluble in alkalies and in ether, bisulphide of carbon, 
alcohol, benzole, and other similar licpiids. When submitted to distillation, 
VOL. IV. — NO. XIV. S 
