TOE CIIESTEK EMERY BED. 135 



There would appear to be one quality in the Chester emery particularly recoin- 

 mending it over the Asiatic variety. It is this, the foreign emery is liable to oxida- 

 tion, while the American is not, it remaining bright and clean alter being moistened 

 and exposed to air. The damage by oxidation is not only a i)artial loss of hardness, 

 but the coating of the particles by rust interferes materially with tlu'ir adhesion to 

 the wheel; consequently a wheel charged with the American emery best retains its 

 charge and accomplishes the most abrasion. That this is a well-ascertained dift'erence 

 between the substances from the two localities is apparent from the invariably rusted 

 appearance of the crude stone coming from the East, whereas the i)roduce of the 

 Chester mine and even the loose stones lying about the vicinity betray not the 

 slightest tendency to oxidation. I am informed also by Mr. Alden, the emery manu- 

 facturer at Fraraiugbam, that he has long been aware of a 2 per cent gain in weight 

 to his manufactured Naxos emery — an increase which under the circumstances may 

 fairly be ascribed to the fixation of atmospheric oxygen in the production of iron 

 rust. It is singular, indeed, that the same mineral, though from different localities, 

 should not exhibit the same phenomenon when subjected to similar conditions; but 

 numerous examples of other minerals are familiar to the mineralogists, presenting the 

 same capricious instability of constitution. 



London, 21 Norfolk street, Strand, 1865, 



GENERAL DESCRIPTION. 



The Westfield River (the Agawam) rims east across the strike until, 

 entering the northvi^est corner of Chester, it sv^^ings round the north end 

 of the broad hornblende band already described, forming the boundary 

 between this and the Middlefield serpentine, and running south through 

 the township nearly with the strike, it occupies a somewhat wider valley, 

 in which is the village of Chester. This valley is excavated in the softer 

 sericite-schists, and the greater durability of the vertical liornblende-schists 

 (amphibolite) finds expression in the sharp ridge of the North j\Iountain — 

 or Gobble Hill, as it is called with less euphony by the inhabitants — which, 

 seen from north or south, rises like a tower and is a prominent landmark. 

 A small brook coming in from the west in a deep, naiTow valley separates 

 it from the South Mountain, which rises to greater height, but is more 

 rounded and falls away southward to the common level of the high ground 

 in Blandford. 



The gi-eat height of these hills, about 750 feet above the village, 1,.583 

 and 1,797 feet above the sea, is due, as said above, to the amphibolite 

 band, and to the south, where this breaks up into several beds intercalated 

 with sericite-schist, the ground falls off". 



