184 ANNUAL REPORT 
Pure Lime Smrtes—Conclunded. 
G4 as) HE 
So labs 
g Sen are 
Ke Clay base. Formula of cement. £ 8h sie 8 Remarks. 
2 Sh |o tm 
Z & | aan 
46 e < 1,250 Broke up in 2 days. 
47 Kaolin 1.5(CaMgO)SiO,, (CaMgO)Al1,0O.,| 850 Broke in clip. 
48 ss - 950 ch 
49 cc ( 1,050 ‘ 
50 is Os 1,250 | « 
51 | Kaolin-flint mixture }1.5(CaMgO)Si0, (CaMgO)A1,0.| 850 89 
52 “ a 950 | 324 
53 = i 1,050 Briquettes broke 
54 (73 6e 1,250 (<9 
55 Kaolin (CaMgO)SiO,, (CaMgO)Al1,0, 850 Briquettes broke. 
56 66 (73 950 (7 
57 (a3 (73 1,050 a3 
58 Ce we 1,250 Slaked. 
59 | Kaolin-flint mixture | (CaMgO)Si0O, (CaMgO)Al1,0O, 850 | 337 
60 ot a 950 | 313 
61 : rf 1,050 Briquettes broke in 
handling. 
62 c c¢ 1,250 w 
The following conclusions may be deduced from a study of the 
above results : | 
rt. The best temperature for burning calcareous Roman cements is 
tooo® C. Below this temperature hydraulicity is not fully developed, 
above it a non-hydraulic compound is evidently produced; whether on 
going still higher hydraulicity is restored has not been determined, but 
seems doubtful. 
2. 
Roman cements having as a clay base pure kaolin are greatly 
inferior to cements containing a silicious clay base in each and every case. 
Whether this inferiority is due to the lack of silica or to the excess of 
alumina cannot be stated. But this seems to indicate that the hydraulicity 
of these cements is pozzuolanic in character. 
3. The pozzuolanic character is emphasized by the fact that a 
decrease of as much as 10 per cent. of calcium oxide does not produce 
