38 PRIMARY OR PALAIOZOIC ROCKS,—\CASE VIII. 
41. Brack SLATE. Map No. Fe 17. 
Same locality as last. 
Containing graptolites. 
42, BLACK SLATE. 
Deddic River, Snowy River, S.E. 
Gippsland. 
Containing white markings of Chias- 
tolite. 
43, BLACK Smarty Rock. 
Map No. R 99. 
Reef in Barfold Ranges. 4 sheet 
13 S.E. 
Occurs in the casing of a quartz reef 
(slickenside); very carbonaceous. 
44, Dark SHALE, Map No. R99. 
Barfold Ranges. 3 sheet 13 S.E. 
Occurs with No. 43. It contains 
veins of carbonate of magnesia, 
45. Sort, WHITE ROCK. 
Sunbury. 4 sheet 7 N.E. 
Finely arenaceous, 
46. BLACK, CARBONACEOUS SHALE. 
Sunbury. 4 sheet 7 N.E. 
Decomposed. 
47. DARK-RED SHALE. 
Sunbury. } sheet 7 N.E. 
The percentage of iron is too great 
to render it fit for a good fire-brick. 
Note.—Specimens 45 to 47 are Silurian rocks, partly decomposed 
and broken up in sitw.—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... ae net ... 93:858 
Alumina ... Sy, xt: xx; eee) 05182 
Magnesia... gx Ese ee <.» trace 
WAVES op we ty see xt: 890 
99°930 

“ It 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 
1 per cent. of lime.” s 
No. 46.—“ A black carbonaceous clay.”—Giving the following 
results :— 

Silica 43 T 308 age DA 66°924 
Alumina ... ay: 75 “1x an NN 
Tron ye n yi tee 10°349 
“Magnesia... oo Je ANS .. trace 
Water, &c. ese fE To +» 6:008 
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.” 
