428 Scientific Proceedings, Royal Dublin Society. 
necessarily indicate an abundance of small fragments of the same 
kind of rock. A general estimate therefore could alone be given; 
and comparative abundance, which partly depends upon the sizes 
of the fragments selected for reckoning, is indicated by the 
numbers 1, 2, 3, 4, 5, according as the species of rock heading a 
column, is occasionally, commonly, abundantly, very abundantly, 
or, almost solely, represented. In giving the results as to car- 
bonate of lime, also, the same numbers are used with similar 
intent, without aiming at strict statement of quantitative results. 
Samples of clays, about 2 lbs. in weight, including pebbles, as 
they naturally occurred therein, were procured from the different 
places named in the Table. Soils and sub-soils, or Upper and 
Lower clays, from each locality, were taken at the same point, 
geographically. All were perfectly dried in the air, and at a ~ 
low oven-heat, and weighed. They were then sifted through 
wire netting of about =3;th-inch mesh, so as to separate all frag- 
ments of such a size as to admit of safe determination. These 
were well rubbed with the fingers over the sieve, so as to remove 
all clay adhering to them, and examined with the aid of a lens, 
after being washed, dried, and cracked with a hammer, so as to 
expose fresh surfaces. Little difficulty was experienced in classi- 
fying and arranging them in the various lithological groups set 
forth in the Table. 
The materials which went through the sieve were again sifted 
through wire netting of ~th-inch gauge. The gravel which lay 
on the sieve was rubbed between the fingers, and lightly triturated 
in a mortar, until no small lumps of clay remained. This was re- 
sifted, and all the clay and fine sand which passed through 
weighed, to ascertain the percentage of their aggregate in the 
samples. 
The relative quantities of carbonate of lime in the samples was 
ascertained by treating the finer gravel and coarse sand with cold 
hydrochloric acid, diluted with about an equal quantity of water. 
The comparative amount present in each case was judged by the 
degree of effervescence caused by the escaping carbonic acid gas. 
It will be noticed, on examining the Table, that soils in lime- 
stone districts are not very calcareous, though they might be 
expected to be so. Chert (appearing in the columns under the 
head of quartz) is to be frequently met with in soils over limestone, 
