88 CHLORINE AND IODINE. 



chapter to the investigation of their constitution 

 in a subsequent part of this work. 



SECT. II. 



OF THE ATOMIC WEIGHT OF IODINE. 



THE properties of iodine were investigated with 

 such sagacity and success by M. Guy-Lussac 

 and Sir H. Davy, that succeeding experimenters 

 have had but little to add to the result of their in- 

 vestigations. I shall mention here the few particu- 

 lars that I have had an opportunity of observing. 

 Specific l. Gay-Lussac states the specific gravity of io- 

 dine to be 4*948 ; but I have reason to believe that 

 this estimate is too high. I sublimed some iodine 

 by exposing it in an eight ounce phial to a very 

 low heat. By this method it may be obtained 

 in pretty large octahedral crystals, approaching 

 to the shape of the primitive form of sulphur. A 

 number of these crystals were picked out, and 

 their specific gravity taken. I found it 3 '0844. 

 The specific gravity of iodine, as originally pre- 

 pared without any purification, is somewhat less, 

 being only 2*915. This difference is owing to 

 the presence of a very small quantity of water. 

 The specific gravity of distilled water saturated 

 with iodine is 1*00021 a sufficient proof of the 



