266 



The proportion of potash in this marl, by analysis, is 10-7 per 

 cent. 



Marl from the farm of Sarah Willis, half a mile northwest 

 of Plattsburg. 

 Description. — Colour, a rich green ; the washed granules have 

 a still richer tint; they are of medium size. 

 Composition. — In 100 parts : 



Greensand, - - - 69*1 

 Clay, . - - . 28-9 



Quartzose sand, - - 2-0 



100-00 

 The proportion of potash in this marl, deduced from that in the 

 greensand, is 7-9 per cent. 



Marl from, the farm, of John Pancoast, half a mile northwest 

 of Plattsburg, Burlington county. 



Description. — Colour, light verdigris-green; the washed granules 

 even lighter in colour; size, small. 

 Composition. — In 100 parts : 



Greensand, - - . 76*50 

 Clay, .... 22-00 



Quartzose sand, - - 1-50 



10000 

 The proportion of potash in this marl, deduced from that in 

 greensand, is 8-7 per cent. 



Marl from the farm of Thomas Earl, three quarters of a mile 

 northwest of Plattsburg. 



Description. — Colour, earthy pea-green ; the washed grains, 

 small in size and of a dark sea-green colour. 

 Composition. — In 100 parts: 



Greensand, - - - 56 

 Clay, .... 36 



Quartzose sand, - - 8 



100 



