No. 50.] 
281 
roasting, is mostly to render the ore more friable, or in some cases to 
expel sulphur. Washing or separation, is a necessary operation in a 
great majority of veins, especially if they are to be worked in a forge. 
If they were to be smelted in the furnace, this process might be omit- 
ted, the stony matter would be in sufficient quantity only to form a flux. 
At one time, the magnet was considered the best instrument for sepa- 
rating the ores ; it is, however, now going out of use. The improved 
mode of separating by washing, has superseded the use of the employ- 
ment of the magnetic machine. Washing the ore is important in more 
considerations than one, as by it, iron of an uniform quality is produced; 
but the removal of the stony matter, alters also, the property of the iron : 
for example, previous to the use of the washing or separating apparatus, 
steel of an excellent quality was often produced, and undoubtedly, with 
extended experience, might have been produced at pleasure. Again, the 
iron produced by the unseparated ores, was remarkable for resisting 
oxidation. Such are some of the modifying effects of the earthy mat- 
ter in mixture with the ore. The Arnold ore, is the only one which is 
employed without separation. Without addition, it makes iron rapidly 
and of the softest kind. Hence, it is much sought after by bloomers, 
and is frequently transported twenty miles on wagons. 
SECTION IX. 
Outline of the Geology of Essex County. 
If an observer should commence his examination of the geology of 
Essex county at Cedar-Point, and proceed west, he would pass over, 
first, a narrow belt of the calciferous sand rock of Eaton, after which, 
he would meet with gneiss, and in the last place, the hypersthene rock, 
which embraces the great masses of magnetic oxide of Newcomb. 
The first rock mentioned, exists, as has been stated, only in a narrow 
belt, which at Cedar-Point is not more than 80 rods in width. It skirts 
the country on its eastern border, but is not continuous. The primary 
strata appear a little north of the iron works of Port-Henry, and occupy 
the whole space between the latter place and Split-Rock. Upon the 
calciferous rock at Cedar-Point, there reposes a thin stratum of tertiary 
clay of the most recent of the marine deposits in this country. In the 
vicinity of Cedar-Point, there also occurs, heavy masses of primary 
limestone, and a mixture of limestone and serpentine. The latter for- 
mations either occupy beds or veins in gneiss, which extend west about 
nine miles. It possesses the ordinary characters of gneiss. It is tra- 
versed at different places by limestone, the hydrous peroxide of iron, 
[Assembly, No. 50.] 36 
