38 PRIMARY OR PALAOZOIC ROCKS.—CASE VIII. 
41. Brack SLATE. Map No.Fe17. | 44. Dark SHALE. Map No. R99, 
Same locality as last. Barfold Ranges, + sheet 13 S.E. 
Containing graptolites. Occurs with No. 43. It contains 
veins of carbonate of magnesia. 
42. BLACK SLATE. 
Deddic River, Snowy River, S.E. go ASO TAERE 
Sunbury. 4 sheet 7 N.E. 
Gippsland. Finel D 
Containing white markings of Chias- DE ar o EEN 
tolite. 46. BLACK, CARBONACEOUS SHALE, 
; Sunbury. 4 sheet 7 N.E. 
48. BLACK SHALY Rock. Decca $ 
Map No. R 99. 
Reef in Barfold Ranges. } sheet | 47. DARK-RED SHALE. 
13 S.E. Sunbury. 3 sheet 7 N.E. 
Occurs in the casing of a quartz reef The percentage of iron is too great 
(slickenside); very carbonaceous. to render it fit for a good fire-brick. 
Wote.—Specimens 45 to 47 are Silurian rocks, partly decomposed 
and broken up ¿n situ—The following remarks and analyses of these 
specimens, 45 to 47, by Mr. J. C. Newbery, may be found interesting:— 
No. 45.—* A white, siliceous clay, makes a good fire-brick, resem- 
bling the Dinas brick from Glamorganshire. It must not be placed in 
those parts of the furnace, where it could be acted on by alkaline fluxes, 
or certain metallic oxides. It also ought to be kept in a dry place, on 
account of its porous nature.”—It gives on analysis— 

Silica... eee sot ee +. 93'858 
Alumina ... Io sa ot co ERED 
Magnesia... aes m 2035 eee tTACE 
Water ™ .,. CG: n Ei res *890 
99°930 

“Tt may be found advantageous to add roughly broken quartz, so as to 
make the brick contract and expand under changes of temperature 
evenly and without cracking. It would also be advisable to add about 
| per cent. of lime.” 
No. 46.—“ A black carbonaceous clay.”—Giving the following 
results :— ; 

Silica... tee T oH: ... 66'924 
Alumina ... nae “Zp tk «+» 17°201 
Tron D: 3 ca aes +» 10349 
Magnesia... on xË az; ... trace 
Water, &c. ak ter see --- 6008 
100°482 

“ These clays would make good fire-bricks, where no lime or any fusible 
substance could come in contact with them, as the presence of such 
substances, together with the large percentage of iron, would cause them 
to fuse.” 

