236 
Chemically the clay and quicksand differ much less than any one 
acquainted with their characteristics would imagine, as the following 
analysis shows:* 
Quicksand. Blue Clay. 
Per Cent. Per Cent. 
Water and carbonic acid........... 18.03 17.38 
Riligal (SO ees | choc el Bane ae 49.48 45.89 d 
ame (Cae aes abc cle Hotere sete aie 10.66 13.44 
Mba gmacnia (Mpt 2 sais cas Scio tele e 7.69 7.67 
a Fprmmanicy (1g OR Ae Fees pecnree a ene 7.80 9.05 
Ironioxid | (He, O a) See 2 tence estas: 5.30 5.68 
bane ORE (Li OE) Were dc). 1-\ 3 aerate 227 21 
99.23 99.32 
In general appearance, also, the two are quite similar, yet, on close 
examination, the limits of the “pockets” are easily determined. Within 
these limits the material is distinctly ‘‘quick sand,’ while without the 
limits it is as distinctively clay. The clay deposit has been used quite 
extensively. It makes a fine white or cream-colored building brick, and 
when vitrified makes a good street paver. It is also used in the manu- 
facture of Portland cement. But manufacturers find that an admixture 
of the quicksand makes the clay difficult to mold by machinery, prevents 
the uniform vitrification necessary for good street pavers, and totally 
destroys its value as an ingredient in the manufacture of Portland cement. 
These quicksand pockets, therefore, injure the commercial value of the 
deposit. 
The presence of these pockets, filled as they are with material differ- 
ing from that which immediately surrounds them, but identical with that 
which underlies the deposit, together with the fact that the clay appears 
to have undergone much disturbance, suggests the possibility that their 
contents may have come from the quicksand stratum beneath the clay. 
The base of the clay has not been reached by any excavation and, 
therefore, no opportunity has been afforded to examine the lower portion 
of the deposit, but at the town of Mishawaka, four miles east of South 
Bend, I had an opportunity during the past season of observing somewhat 
similar phenomena. In a sewer trench on Second street, in that town, 
there appears a deposit of clay from one to four feet thick, overlying 
* Analysis by Wm. M. Whitten, Jr., B.S., M.8. 
ye ets 
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