SATE TCHOLOGISI 1A 
to soak in water for 24 hours. If this was not sufficient, boiling was re- 
sorted to, which was kept up for 6 to 8 hours, if necessary. The mass 
was then evaporated to dryness and rubbed through a 40 mesh sieve. 
For very hard material, rubbing with a rubber pestle may be permitted. 
Mixing.—The sample was now ready to be mixed with the lime. This 
was done by weighing out about 25 grams of the clay to be examined, 
whose gross analysis must be known, stirring it up with water to a thin 
slip and adding reprecipitated calcium carbonate. This mixture was 
stirred thoroughly, evaporated to dryness, rubbed through a 20 mesh sieve 
and thoroughly mixed with a spatula. 
- At this stage of the work it was necessary to determine the proper 
amount of lime to be added to a clay so as to attain the object sought, that 
is, the decomposition of the clay substance proper and the formation of a 
lime silicate, without running into danger of fusing the resulting mixture 
at the temperature employed in heating. In order to accomplish this a 
series of test-mixtures was made, employing a very fine-grained, soft 
clay, with little bonding power, which is used in the manufacture of Port- 
land cement, at Harper, Ohio. ‘The clay has the following analysis: 
SLO erro eee ees ert ies pitch tertam: sie camara wossata Cages 50.70 
INE OSE HELO Rare pnt denn ev oR a olan atv A atv 17.00 
(CRI CORES Os ol aice or me One cache er Ne PERS Sa ROH OCP 16.80 
MUR OO seme so Sah Sok CeO Ol nee Ie Cet oes ne aE ee eas 9.80 
The clay by itself was made the start of the series and the lime 
was increased as shown by the following table. The mixtures were 
burned at a temperature of I100° C., this heat being maintained for 75 
minutes. The mixtures of clay and calcium carbonate were made up 
into briquettes weighing about 75 grams, with the atd of water, placed 
upon a biscuit plate and burned in the small furnace used for this purpose. 
Per cent. of Pancent 
No. 6 Galen: _| Residue. Remarks. 
1 16.8 ties Clay alone. 
Be DB, 
3 | 30. ae 
4 30. nee More or less completely fused. 
5 40. 
6 45. 
7 50. eset 
8 5D. og: Vitrified. 
9 60. 3.59 Quite hard. 
10 65. eae Hard. 
11 Or | LIZ Soft, but somewhat too hard for easy reduction. 
12 80. | 2.16 Soft. 
13 85. | 3.00 | Soft and friable. ; 
No. 11 of the table must be considered doubtful, an error having cer- 
tainly been made in the analytical work. The results of the table show that 
