134 



EFFF.CTS OF GRAVITY ON TIMEPIECES, 



Arseniated co- 

 balt. 



Natireantimo- 



Sulphuret of 

 antimony. 



Oxide of an- 

 timony. 



Hidrosulphu- 

 ret of antimo- 

 ny. 



Arsenic. 

 Titanium. 



Arseniated cobalt is met with in some veins, but never 

 forms veins of itself. It pretty frequently indicates the 

 proximity of veins of argentiferous oxide of iron. The ar- 

 gentiferous earthy arseniate of cobalt at Allemont contains 

 from 1 , 2, or 3 ten thousandth parts of silver to ten or twelve 

 per cent. 



Native antimony is very rare at Chalancbes. It is in large 

 or small shining metallic scales confusedly arranged, and 

 forming masses capable of being divided parallel to the fa- 

 ces both of a regular octaedron and a rhomboidal dodecae- 

 dron. Sometimes it is in solid compact nodules capable of 

 being cut and polished. The presence of arsenic, though 

 in very small quantity, changes entirely the texture of the 

 antimony. In this state it forms a kind of scales, the sur- 

 face of which is frequently undulated. 



Sulphuretted antimony is found in the same situations as 

 the preceding, but it is infinitely more scarce. It is prisma- 

 tic or laminar, but more commonly amorphous. 



Oxided antimony occurs in rectangular crystalline lami- 

 nae in the interior of the native antimony ; but more fre- 

 quently pulverulent, white, and earthy, on the surface of 

 the nodules with large facets. 



Hidrosulphuretted antimony is still more rare than the 

 preceding species, but it is found with the oxide in the su- 

 perficial cavities of the native antimony with large facets. 



Arsenic is never found native, but is sometimes combined 

 with the nickel, cobalt, or antimony. 



The greenish or blackish amphibolic rocks frequently con- 

 tain lemon-coloured crystals, which have been found to be 

 a siliceo-calcareous ore of titanium. 



VI, 



Effects of Gravity on the Balance of a Watch compared with 

 those on the Pendutym of a Clock, In a Letter from 

 a Correspondent. 



To Mr. NICHOLSON. 

 SIR, 



(a) JL Have been often led to compare the balance of the 

 ▼ity on the ba- watch with the pendulum of the clock. The functions of 



both 



