230 ANNUAL REPORT 
Composition of Two Vitrified Cements, by Tetmayer. 
Per Cents. 
A. | Be 
Silicasensenee 17.06 19.92 
ALU ae ea oe eee emo 5.28 7.01 
Herricio xd ea: ere eee eee 3.07 Ds 
Limeieeoveers Piper Noe ceca aie 48 45 35.29 
Malanesiareeen acer 2S 8.39 
Calcrimysulphatesaeneee eee ee 1.85 2.43 
WGossronmonitioneeer een 6.36 4.57 
Tensile and Crushing Tests of Two Vitrified Cements, by Tetmayer. 
5 “S gi ; Zi satel mae z 
Z 2 A s nN % x 19 © 0 S 
Tensile strength | 20.1 | 45.6} 39.0| 39.1] 43.7| 38.8! 41.0) 44.1 | 43.4 
Crushing strength! 118.9 | 231.6 | 293.8 | 406.2 | 393.8 | 379.0 | 455.6 | 421.0 | 413.8 
= Tensile strength 33.5 57.9 | 57.3 | 60.5} 68.0] 60.3 | 60.4] 64.8) 63.5 
Crushing strength] 207.6 | 363.8 |......|...... DAK Ilo -cro 3 6c DIM joe ood 614.7 
| 
In 1893 Kawalewsky made an extensive report on vitrified magnesia 
cements which after ten years were still found to be in excellent condi- 
tion and showing great strength. 
Golinelli in 1895 reported a carefully arranged series of tests with 
magnesium Portland cements containing an average of 26 per cent. of 
magnesium oxide and corresponding to the ratio 
Ca0O+MegO LARS 
SiO, EN Ost eOn 
The silica-alumina ratio maintained was 3. These cements pos- 
sessed most excellent strength and were entirely constant in volume. 
This investigator came to the conclusion that magnesia may be substi- 
tuted for lime. On the other hand, it cannot be denied that some high 
magnesia cements have given trouble in practice, as a number of well 
authenticated cases are on record. This, together with the consideration 
~ 
