a, ANNUAL REPORT 
Ratio : 
T ] 
cues Formula Minerals. 
RO 
0.67 | R,SiO,;...| Gehlenite (RO),Al,0;(SiO), Tetragonal. 
1.00 | R,SiO,...]| Melilite (RO),.(Al,0;).(SiO,), Tetragonal. t 
1.00 “,..| Olivine (MgO),Si0, Rhombic. 
1.00| “  ...| Fayalite (FeO),SiO, c 
1.00 use hephroe (Min ©) ssiOnc ws. 
1.00 ““,...| Montecellite CaOMgOSi0O, “ 
1.00; “  ...| Willemite (Zn0),SiO,  “ 
1.50 | R4Si,0,0.| New, non-aluminous, calcareous, tetragonal, mineral: 
akermanite, R4S1,0,; 9 
2.00 | RSiO,....| Calcium Silicate, CaSiO,;, hexagonal. 
2.00 ‘« ....| Wollastonite, CaSiO,, mono symmetrical. 
2.00 “....| Augite varieties CaO(Mg)Si0,, mono symmetrical. 
2.00 “,...| Babingtonite n(Mn,R)SiO,+Fe.Si,0,, Asymetrical. 
2.00 ““ _.,...| Enstatite, MgSi0,, Rhombic. 
2.00 soo ol debian ave avs | 
Fe,Mg,Si0,, Rhombic. 
2.00 a Sa lh  BURO KOH f 
In regard to the relation between the minerals and the composition 
of the slag, Vogt says: “A comparative examination of the analyses 
shows that the formation of minerals in the molten mass depends chiefly 
on the chemical composition of the average mass. The divergent physical 
conditions possible in the formation of the slags exert only a minimum 
secondary influence on the reaction provided a certain minimum time limit 
be not exceeded for the period of crystallization.” 
Calcined Clay.—Whenever dehydrated clay is required for pozzuo- 
lane purposes, be it for a pozzuolane cement proper or for mixture with 
Porltnad cement, it is of course readily obtained by calcining the clay 
either in a vertical shaft kiln similar to a limekiln or in a rotary cylinder 
furnace. 
RAW MATERIALS OF THE NATURAL CEMENT INDUSTRY. 
By natural cement we mean those natural, intimate mixtures of cal- 
cium carbonate and clay which when burnt to a temperature of ap- 
proximately goo to 1000° C. produce a hydraulic cement. TheUnited States 
are rich in materials of this kind, and these cements have been an im- 
