72 Action of Ammonia on Metallic Copper. — Glass. 



U you happen to be in England on receiving this, pray 

 give my kind remembrances to your father and friends ge- 

 nerally ; and believe me to be, with sincerest wishes for your 

 happiness and welfare, 



Your faithful friend, 



J. Ritchie. 



ACTION OF AMMONIA- ON METALLIC COPPER. 



Dr. Macculloch has observed, that metallic copper dis- 

 solves rapidly in solution of ammonia at a boiling heat; the 

 water bem" decomposed during the process, its oxygen united 

 to the copper, and its hydrogen evolved in the gaseous form. 

 He suggests the application of this process to the purpose of 

 colouring gold trinkets, as it is called, or dissolving out to 

 a certain depth the copper of the alloy they consist of, so as 

 to leave a coat of pure gold on their surface.— Brewster's New 

 Journal, vol. i. p. 75. 



IMPERMEABILITY OF GLASS TO WATER UNDER HIGH 

 PRESSURE. 



It was lately maintained by Mr. Deuchar, in a paper in the 

 Philosophical Magazine, vol. lx. p. 310, that from the porous 

 nature of certain siliceous bodies, it was extremely probable 

 that the fluids in minerals had been forced through their mass 

 by pressure, and that the water which is found in well-stopped 

 bottles, when sunk to great depths in the ocean, has been 

 forced through the pores of the glass. 



The Rev. Mr. Campbell, in a voyage to South Africa, car- 

 ried out with him two crystal globular bottles hermetically 

 sealed, and made on purpose by Messrs. Pellet and Green, 

 St. Paul's Churchyard. In lat 14° 27' N. and to the W. of 

 the Cape de Verd Islands, they were sunk from on board the 

 Westmorland, to a depth of 200 fathoms, or 1 200 feet, by means 

 of two leads, the one of 22 and the other of 28 lbs. When the 

 rope was brought up, by the exertion of ten men, for a quarter 

 of an hour, the two globular bottles were found empty. A wine 

 bottle, sent down at the same time, corked and plastered over 

 with rosin, came up full of water, with the cork inverted ; five 

 other bottles were full of water, but the corks and rosin of 

 these were in the same state as when let down. Another wine- 

 bottle had the pitch remaining entire on its mouth ; but the 

 inside was nearly full of water, in which also the cork was 

 swimming. The water in the inside of the bottles was not 

 more fresh than before its entrance. — Campbell's Second Jour- 

 ney in Africa, vol. ii. p. 383, quoted in Brewster's New Journal, 

 vol. i. p. 189. 



