Vol.-I, No. 6.] Note on Bundelkhand Gneiss, 169 
PNG S| 
The clay was tested for its capacity of forming a china or 
earthenware in the following manner :— 
1. About 20 grams of the dry clay was mixed with sufficient 
water to give a plastic clay, which was moulded into the form of a 
triangular pyramid. This was dried at 100°, then baked for 33 
hours in a gas mufile, at a temperature of 890°. The resulting 
mass was pink in colour, easily broken, possessed httle cohesion, 
was soft and friable. 
2. Another portion of the clay was mixed with calcium car- 
bonate, in proportion to give a mixture containing 2°/, added cal- 
cium carbonate (196 grams clay, 4 grams CaCO,). This was 
moistened, kneaded, and the resulting plastic clay formed into a 
pyramid as before. This was dried at 100°, and heated in a blast 
muflle, together with the pyramid used in the first experiment 
(made from clay alone). Pyramids charged into cold muffle and 
muffle it at 9-10 a.m., on 8th November, 1904. 
Temperature at 11-10 a.m. ah 1155° 
55° ,, 12 noon a 940° 
5 ,, 12-30 P.M. Are 1150° 
‘5 5» IPM. se 1300° 
Heating was then discontinued as one of the pyramids was 
seen to be sinking, the result of incipient fusion. The muffle was 
turned out at 1lp.m. Pyramids drawn at 2-15 p.m., and broken. 
Clay alone.—Pyramid had sunk considerably. Was smooth, 
glazed, dirty brown on the outside. The fracture was highly 
orous and cindery. Heated to a temperature as high as this 
(1300°), the clay would not be of any use as earthenware. 
Clay + 2,/° CaCO,;.—The surface of the pyramid was 
smoother and more highly glazed than that of pyramid just 
described, and the mass had sunk more, indicating that the clay 
mixed with 2,/° CaCO, is more fusible than the clay alone. The 
colour of the exterior was dark brown. A fracture showed a 
porous, spongy layer under the surface, then a more compact, blue- 
black central mass. Useless as earthenware. 
3. The earth was made into a plastic clay as before, without 
any admixture (except water) and formed into a pyramid, and a 
small dish. These were dried at 100°, charged into cold muffle, 
and muffle lit at 9-15 a.m., on 9th November, 1904. 
Temperature at 11 a.m, 200 1030° 
44 TESTO) + Fg 930° 
“p 11-50 _,, es 1050° 
“ 12-25 P.M. 500 1060° 
‘ i ae rap 10905 
5, 1-30 ,, we 1130° 
45 2-15 .,, as 980° 
09 3 Aap EL Ms 950° 
s 3-30 ,, 60 1130° 
9 4-15 ,, fein , 1070° 
