IMPROVED JURY MAST AND SHROUDS. 357 



% A hundred parts of black oxide contain 77 of iron Oxides of iron, 

 and 23 of oxigen. The red oxide is composed of 70*5 

 iron, and 295 oxigen. 



3. The red oxide of iron, on being exposed to a white 

 heat, is brought back to the state of black oxide: but a 

 red heat does not change its nature, though it may alter its 

 colour. 



4. The change of black oxide to red is accelerated by 

 calcination with caustic potash. 



5. An oxide may contain one half of oxide at a maximum, 

 notwithstanding it is strongly attracted by the magnet. 



6. The black oxide is with difficalty soluble in nitric acid, 

 requiring to be long boiled in concentrated acid. 



7. The red oxide is not so insoluble in nitric acid as has 

 been supposed. 



8. Lastly, the red oxide may form different combinations 

 with sulphuric acid ; one of a reddish brown, and soluble ; 

 the other white, 'and insoluble in water, but soluble ia 

 acids. 



VII. 



Letter from Captain William Bolton of the Royal Navj/, 

 on his improved Jury Masts, and on a Contrivance for 

 better securing the Shrouds of Ships*, 



SIR, 



• Jb INDING some doubts were entertained relative to the Advantages of 

 practicability of rigging jury masts, upon the plan I had the ton's method 



of rigging jury 

 * Trans, of Soc. of Arts, vol. xxvii, p. 189. Some doubts masts, 

 having arisen as to the practicability of rigging Captain William 

 Bolton's improved jury masts, described in vol. xxvi, page 167, of 

 the Society's Transactions, (see Journal, vol. xxiv, p. 44) he in 

 consequence has sent to the Society another model thereof com- 

 pletely rigged, which obviates all difficulty therein; and likewise 

 has added another invention of his contrivance, for the better se- 

 curing the shrouds of rigging; explanatory engravings of both are 

 annexed, and the model is preserved in the Society's Repository, 

 The gold medal of the society was voted to Captain Bolton for his 

 naval improvements. 



honour 



