212 ANNUAL REPORT 
minate and ferrate lose all of their lime, so that, together with the calcium 
oxide already free, 43.18 per cent. of calcium hydrate is formed. 
In determining the water of hydration there was found after 
Per cent. 
UAT Fh en waeetre ter Mn CUR ame mea oie AAU A ke a 4.30 
AES VIS UNE MS sesh, oi eo Oe erie ci YE a eae Co gee 6.47 
US CLAY Sites ao A ai't oh ace Ee ES ee eS 2 
Dib AS i 5 Gh fel Be OR eae arr 14.44 
DOMUAY SE Ard he ee Sao reccest nae te Ae Ghee ROC 14.44 
agreeing quite closely with the theory. 
Finally Zulkowski pictures the formation of hydraulic cements as 
follows, assuming that the reaction starts with the ideal clay base, 
kaolin: 
rt. On the dehydration of the kaolin and expulsion of carbon dioxide 
a temporary product is formed by the replacement of the two molecules 
of water by two molecules of lime, thus, 2SiO,A1,0,2CaO. 
2. Addition of another molecule of lime forming a more basic 
limve-alumina silicate” 2¢€a®Si©z), Ca©Al@.. Whe ‘silicatesisn net a 
hydrolite, but the aluminate is, the lime going off as hydrate and the 
alumina also as hydroxide. 
3. With increasing heat both the mono-calcium compounds change 
to di-calcium silicate and aluminate and all the lime beyond the amount 
necessary for this purpose remains as free lime. 
If for one molecule of pure kaolin in place of the 6 molecules of lime 
necessary only 5 molecules are taken dusting will take place. 
The Work of Meyer.—Equally interesting are the results obtained by 
Meyer,* who followed in his experiments more closely the work of 
Chatelier. He prepared cements without alumina, using iron and man- 
ganese oxide as fluxes, and had no difficulty in producing tri-calcitum 
silicate, which appeared in colorless crystals as found in ordinary 
cements. If the temperature is carried too high, white crystals will be 
found floating in the mass, corresponding to 3CaOSi0O,. This must be the 
main hydraulic agent. No aluminates or ferrates are formed, as the 
alumina and iron must be united with the silicate. 
The claim of Zulkowski that the silicate is present as the di-calcium 
meta-silicate is considered erroneous by Meyer, who claims that this 
compound could not exist together with free lime. At the same time 
Meyer does not believe that the tri-calcium silicate can be produced by 
direct synthesis, but must be prepared by crystallization from a fused 
magma. The presence of a meta-dicalcium silicate Meyer considers 
impossible, since, according to him, the tri-calcium silicate hydrates to 
2CaOSiO,H,O, which loses half of the fixed water at 160° C., while 
* Meyer, Tonindustrie Ztg., No. 144, 1902. 
