LAGUNA CLAYS. 



383 



tive. I excavated one to a depth of over two meters and then bored 

 on a slant in two directions with a post-hole auger for 1-J meters more. 

 On one side the material was gritty and only partially weathered, 

 while on the other a very good, nniform, sample of kaolin was obtained. 

 The latter was investigated in the laboratory with the following results : 



Chemical analysis. 

 [Figures give percentages.] 



Silica 

 (SiOo). 



Alu- 

 mina 

 (AI2O3) 



Fluxes. 



Loss on 

 igni- 

 tion. « 



Water 



bell'ow 

 110°. 



Tita- 

 nium 

 oxide 

 (TiOo) 



Manga- 

 nese 

 oxide 

 (MnO). 



Total 

 fluxes. 



Total 

 iron 



given as 

 ferric 

 oxide 



(fesOs) 



Lime 

 (CaO). 



Magne- 

 nesia 

 (MgO). 



Soda 

 (Na.0). 



Potash 

 (KoO). 



49.42 

 i> 52. 45 



30.45 

 ''32.3 



1.61 



blT.l 



0.00 

 I'D. 00 



0.21 

 '■0.22 



0.07 

 "0.07 



0.09 

 "O.IO 



11.72 

 '■12.43 



5.86 

 I'D. 00 



1.11 

 "1.18 



trace. 

 i> trace. 



1.98 

 "2.10 



' Mostly water above 110°. ^ Recalculated free from, water below 110° 



Physical properties. 



Water 

 added 

 to give 

 a work- 

 able 

 paste 

 (per 

 cent 

 total 

 weight) 



Tensile strength. 



Shrinkage (per cent). 



Color. 



Air dried. 



Burned." 



Air. 



Fire at 

 cone 

 No. 9. 



Total. 



Air dried. 



Burned with free 

 access of air. 



Kilos 



per 

 square 

 centi- 

 meter. 



Pounds 



per 

 square 

 inch. 



Kilos 



per 



square 



centi- 

 meter. 



Pounds 



per 

 square 

 inch. 



38.6 



1.56 



22.2 



4.22 



60 



5.2 



6.3 



11.5 



Creamy white 



Light creamy 

 white. 



" Does not crackle. 



The other pit excavated to a depth of a meter and then bored on a 



slant in one direction yielded quite a different sample. This contained 



a small amount of pyrites and when moist was of a bluish tint. The 



natives say that material of this quality formerly overlay the whole 



deposit of white clay. The laboratory data and results on this sample 



are as follows: 



Chemical analysis. 



[Figures give percentages.] 



Silica 

 (SiOo). 



Alumina 

 (AI0O3). 



Fluxes. 



Loss on 

 igni- 

 tion.' 



Water 

 (H,0) 

 below 

 110°. 



Tita- 

 nium 

 oxide 

 (TiOo) 



Total 

 iron 

 given as 

 ferric 

 oxide 



(re.o,,). 



Lime 

 (CaO). 



Mag- 

 nesia 

 (MgO). 



Soda 

 (NasO). 



Potash 

 (K2O). 



43.83 

 i'45.0 



31.86 

 '>32.7 



5.86 

 ''6.03 



0.14. 

 '0.1.5. 



0.11 

 I'D.!! 



small 

 '' small 



small, 

 ''small. 



15.04 

 "15.44 



2.71 

 "0.00 



0.80 

 "0.82 



" Mostly water above 110° 



^ Recalculated free from water below 110.' 



