STATE GEOLOGIST. 
with kaolin and determining their melting 
the marble by Portland cement. 
His results 
points. 
313 
He also replaced 
are found in the following 
table: 
é Percentage 
2 Proportion for 100 a8 Composition: Melting point 
Ss parts by weight Formula. oe a on replacing the 
= of marble. 2.6% | marble by cement, 
=) ©) Sa CaO Ale O3} SiO ) 
Z = | 
1 | 120 parts sand CaO028i0, below 26 | 31-8 )..... 68.2 | much below 26 
2 Al,O,28i0, | | Bm oa. 46.2 | 53.8 
3 | 180 parts sand CaQ3si0, 29-30) |.23.7 |... =. 76.3 below 26 
4 Al,0,3810, Sot sl eiin 36.4 | 63.6 | 
5 | 240 parts sand CaO04Si0, \ 4 |) Weioe) ib wees 81.1 29 
6 Al,0,48i0, | Bo lawn 30.0 | 70.0 
7 | 518 parts kaolin Peace much below 26 | 11.2 | 41.0 | 47.8 below 26 
8 | 480 parts sand CaO8siO, | B78 | MOL We bo 6s 89.6 31 
9 |ALO; Al,O,8810, AS Aare ee 17.6 | 82.4 
10 | 1,036 parts kaolin) gat 4120s) 30-31 | 5.9 | 43.5 | 50.6 30 
2 
These experiments indicate that the fusing effect of excessive lime on 
sand is much less than has been realized so far. A mixture of 76.3 
per cent. of silica and 23.7 per cent. calcium oxide still requires a tem- 
perature of cone 29 for fusion and the CaO4SiO, mixture, 18.9 per cent. 
calcium oxide and 81.1 per cent. of silica has a melting point of cone 
32. At the same time 5.6 per cent. of calcium oxide suffices to lower 
a clay melting at cone 35 to cone 26. This seems to explain why lime 
burners have used quartzite for lining their kilns. However, the case is 
evidently different with cement, which contains beside lime and silica, 
alumina, iron and alkalies. 
Fire bricks are tested with regard to their use in cement kilns not 
so much for refractoriness as for physical structure, though, of course, 
it is understood that a clay should never fuse or soften below cone 30. 
Some manufacturers test the brick by heating them ta redness and 
dropping them into water. If the bricks do not crack they are consid- 
ered satisfactory. Really comparative tests have as yet not been worked 
cut. The pyrometric tests are made in a Deville or electric furnace. 
Basic Linings.—Besides clay bricks, basic linings have been pro- 
posed. These, if they could be realized, would be the most suitable 
materials. 
