CLAYS OF MIDDLESEX COUNTY. 449 



It is rather porous burning, in spite of its high fire shrinkage 

 at cone 10. 



Several samples were also tested from C. S. Edgar's bank 

 (Freeman bank) (Loc. 94). The section (exposed in Sept., 

 1901) is given below, in order to better identify the samples : 



Section at C. S. Edgar's bank, near Sand Hills. 



1. Sandy clay, full of iron crusts, 7-10 ft. 



2. Mottled blue and black clay, called top clay, 3 " 



3. Yellow sandy clay, . 1^2 " 



4. Blue clay, 1 1 / 2 " 



5. Black clay with much lignite, 5 " 



6. Light blue, sandy clay, 1-3 " 



7. No. 1 blue fire clay, 7 " 



A sample from layer 7 (Lab. No. 405) was a homogeneous 

 gritty clay of porous texture and smooth fracture. It slaked 

 fairly fast and all passed through a 100-mesh sieve. When mixed 

 with 32 per cent, water it gave a mass of moderate plasticity, 

 whose tensile strength was 52 pounds per square inch and air 

 -shrinkage 7 per cent. It behaved as follows when fired : 



Burning tests of a No. 1 blue fire clay, C. S. Edgar, Sand Hills. 



Cone 01 1 5 15 



Fire shrinkage, 2% 3% 5% 9.6% 



Absorption, 19.69% 16.75% 4-87% 



Color, whitish yellowish white yellowish white buff 



As is shown by the absorption tests this is a rather open-burn- 

 ing clay, and does not become at all dense until cone 15. It 

 burns steel-hard at cone 5, and at cone 27 is vitrified. This is 

 a sagger clay. 



A second sample tested from this pit was a mixture of layers 

 2 and 4 of the section given above. This mixture (Lab. No. 

 406) worked up with 25 per cent, of water, and had an average 

 tensile strength of 98 pounds per square inch with an air shrink- 

 age of 6.5 per cent. Its burning qualities were as follows: 



29 cl G 



