2 
oat 
objection to the dry use of any stone. The free use of water 
overcomes the objection 
Oil, however, is more frequently used with the fine-grained 
stones. As it is thicker than water, it keeps the powder out of the 
pores by holding it on the surface of the stone, where it acts like 
a polishing powder in giving a finer edge to the tool. Very little 
oil is necessary, and it is better in every case to carefully wipe 
off the same after using and thus prevent the formation of a glaze 
due to the hardening of the oil and powder. Ojlstones should 
always be kept moist thus preventing the formation of a hard 
gum by the drying of the oil. Frequently, porous stones are 
ruined by the hardening of oil in the pores of the stone. 
CUTTING QUALITIES. Sandstones, which are used for 
whetstone purposes, are divided into two kinds, the coarser and 
the finer, the Labrador stone being one of the latter. Two other 
fine sandstones have become more than locally famous, the Hin- 
dostan and the Adamascobite stones. The Labrador stone is 
harder and coarser than the others, its grain averaging 1-20 of 
a millimeter in diameter. In the common scythe stone they are 
1-5 of a millimeter in diameter. As the work done is propor- 
tional to the cubes of the diameters of the grains, the Labrador 
stone does work sixty-four times as fine as the scythe stone, that 
is it will produce sixty-four furrows or scratches to one of the 
other. The Hindostan averages 1-50 of a millimeter in diameter 
and is fifteen times finer than the Labrador stone. The Arkansas 
stone also cut at the Manlius factory, is 1-100 of a millimeter in 
diameter and is thus eight times as fine as the Hindostan, 125 
times as fine as the Labrador, and 8,000 times as fine as the 
scythe stone. Thus it may be seen that while the Labrador stone 
does not give a fine finish, still it is a great improvement over the 
common scythe stone, giving a good cutting edge for many kinds 
of work. 
Griswold* gives the following microscopic description of a 
slide of the Labrador oilstone: “This stone is a fine-grained 
*Annual Report of the Geological Survey of Arkansas for 1890 Volume 
III. Novalculites, by L. S. Griswold. 
