ile, ANNUAL REPORT 
fact that these are of great importance in governing the refractoriness of 
a clay. In considering the composition of a fire clay even the small 
amounts of fluxes and potash must not be neglected inasmuch as they 
exert an important solving action. A commercial kaolin of good qual- 
ity (from Ledetz) was found to have the quotient 34.26 and did not 
fuse at the melting point of platinum, but appeared slightly translucent 
with the edges still sharp; a porcelain body of the composition: 
Per cents. 
Clayosubstance aye cg ese ae rt hentai st he Man orae 54.92 
Reldspareica.a-. eo S hee he Shae ea onGre ola a One a 21.56 
Quart Zier onic coe tite ye Oeics ty Beate Ren riiyl | nome Basa coer 23.52 
having the quotient 10.29 fused to a glass and a brick clay, quotient 0.71 
began to fuse at the melting point of cast iron. 
The relative fusibilities of fire clays are hence fairly established by 
this ratio. Seger’s, Bischof’s and other refractory quotients are based 
on the following general laws of fusibility of fire clays derived largely 
from the work of Richter: 
1. The refractoriness of clays is dependent upon the proportion 
of flux to silica and alumina. 
2. The fluxing action of the various bases is proportional to their 
molecular weights. Thus 40 parts of magnesia exert the same fluxing 
action as 56 parts of lime or 62 parts of soda. 
3. The fluxes are more active in a silicious than in an aluminous 
clay. 
4. The most essential factor is the ratio of silica to alumina; the 
more aluminous the clays are the more refractory they will be. 
5. If alumina is present in small amount it plays the role of a flux. 
The following analyses represent fire clays which have given 
good satisfaction in cement kilns: 
: E eae ae Z| 
NG: 5 a | £2. | ee 5 5 4 E 2s 
= e Be | z Sf Bob we 
D a HO HO 3 = ai R e)=3 
DOES | : if 2 ee 
1 | 45.65 } 39.96 | 0.14 0.21 | 0.12 | 0.18 | ls. 7s 
2 | 46.20 | 39.35 | 0.10 0.15 | 0.09 | 0.22 | 14.00 
B | Mos | B7.08 | 2.70 | 0.30 | 0.21 0.98 13.05 
4 | 45,42 | 36.80 | 3.33 | 0.87 | 0.45 12.65 
It will be noted that these analyses represent raw clays. 
In order to study the effect of lime on sand and clay Cramer 
carried out a series of experiments by mixing marble with sand and 
