GENERAL A\ALYSIS OF RESULTS.
The foregoing detailed discussion of the various elements affecting the manner in which silicate mixtures fuse, has been given in addition to the more general statements on pages 214 and 232 so as to make more plain the deductions that are to be drawn from our own data. This detailed citation, it is hoped, has clearly demonstrated that our present knowledge of the influence of the several factors even in simple mixtures is very fragmentary and that in the more complex mixtures the evidence is, in the main, either conflicting or entirely lacking. In the following analysis of the chemical data obtained by this Survey, and at tempts to show a relation between the chemical and physical constitution of the clays, their pyro-physical behavior, and toughness of the burned bricks, Ill:oral assumptions must be made and only general conclusions, if any, drawn.
These assumptions are : First, Those elements which are supposed to increase the viscosity of the mass when fused lengthen the vitrifying range of the clay and increase the toughness of vitrified wares. Sec ond, Those chemical or physical factors which tend to make the mass more fusible or to hasten the pyro-chemical reactions which result in vitrification are detrimental to development of toughness.. Third, That lime is detrimental both to slow fusion and toughness, while magnesia is beneficial. Fourth, That the higher the acid content, or its equivalent, the oxygen ratio, the more viscous will be the fused ingredients and the tougher the burned ware. Fifth, The higher the proportion of A1=0; to other basic oxides the slower will be the fusion, the more viscous the fused ingredients and the tougher the mass. Sixth, The finer the ma terial of which clay is composed, the more rapidly will it fuse and the more brittle will be the burned mass.
In the following table will be found the ratio mentioned in the fore going assumptions, as calculated from the chemical data given on pages 21:i and 21G. In the first column is the ratio of CaO to MgO. In this ratio, Ca0 is taken as unity. In the second column is given the total oxygen in the basic oxides where a203 is unity.
In summing up the oxygen atoms, the iron oxides were considered as reported, i. e., where Fc0 is given, only one atom of oxygen to one
atom of Fe, and where Fe203 is given, three atoms of oxygen to two atoms of Fe were taken. The difference between the value given in the second column and 3 (oxygen in gives the factors for the proportion of oxygen in A1-0, to oxygen in the other bases; i. e., (a-3) : 3 : :0 in fluxes: 0 in In the third column is given the number of atoms of oxygen in total SiO. In the fourth column is given the ratio between oxygen in Si02 to oxygen in total bases. This ratio is known as the oxygen ratio and is customarily taken as the ratio of the acids to the bases. In the fifth column is given the surface factor rep resenting fineness of grain by the writer's method. In the sixth col A.B.C.
umn is a modulus calculated on the formula = Ali where D.
"A" is the lime-magnesia ratio, "B" the total oxygen ratio, "C" the ratio of oxygen in the Ro bases to oxygen in Al203, and "D" the sur face factor divided by 100. In the seventh column is given the rattler loss determined on commercially manufactured blocks ade from each clay.
Deductions Drawn, from Table XLI—Without going into details con cerning the probable reason for the lack of correlation between the chem ical and physical constitution and the toughness of the burned ware as shown in the above data, it is sufficient to state that it be granted that these data corroborate those of Ogden, proving that our notions about the relation of the chemical and physical constitution of clays to the toughness that is developed in burning are in the main, if not wholly, erroneous. Data on mineralogical composition as obtained by the Rational Analysis, gave results that were still less easily correlated with data on toughness of the burned ware than are those in the above table. Before such data can possibly be of value there must be consider ably more learned concerning the fusing behavior and the physical prop erties of sintered masses of simple mixtures of minerals. There is not much of any hope of learning much concerning these relations from data obtained by any process of chemical analysis now used.