Me ee eps byte ee Tae 
REMOVAL OF SILVER AND GOLD BY MUNTZ METAL. 353 
(about ten ounces) in a wooden box perforated on all sides, a few 
feet under the surface of the Pacific Ocean. When occasion offers 
the box is towed by a line at the stern of a vessel which is trading 
up and down the coast of Chili. It is almost too soon to expect 
any decisive results at present, but in a few months I hope to be 
enabled to send both the original copper, and that which has been 
' exposed to the action of the sea.” 
Ido not know whether Mr. Field ever published the results, 
but I have not come across any reference to them. 
“On the composition of sea-water in different parts of the ocean, 
by Professor Georg Forchhammer.!—‘“ Silver—Malaguti first 
showed that silver occurs in the organisms of the sea; I have 
subsequently proved it to exist in a coral, a Pocillopora, and 
several chemists have since tried to prove that silver is precipi- 
tated by the galvanic current between the copper coating of a 
vessel and sea-water. If the last determination is confirmed, the 
existence of silver in sea-water is proved by direct experiment. 
From the Pocillopora alcicornis I have separated it in the follow- 
ing manner :—I dissolved the coral in muriatic acid, precipitated 
the solution by hydrosulphate of ammonia, and dissolved the pre- 
tipitate, which consisted of sulphurets, of phosphate of lime, and 
fluoride of calcium, in very weak cold muriatic acid, which left 
the sulphurets of silver, lead, and copper probably mixed with 
those of cobalt and nickel. ‘These sulphurets were separated from 
the solution, evaporated to dryness with a little nitric acid, to 
Which were added a few drops of muriatie acid, and dissolved in 
Water, which leaves sulphate of lead and chloride of silver undis- 
‘olved. When the filter which contained the latter substances is 
burnt, the silver is reduced to metal; a solution of pure soda will . 
dissolve the sulphate of lead and leave the silver, which, when. 
dissolved in nitric acid, can be tested with muriatic acid. I 
obtained from Pocillopora alcicornis about scot ove, oF from & 
‘lid cubic foot of the coral about half a grain of silver.” ‘ 
1 Phil. Transactions, 1865, pp. 211, 212. 
W—Oct. 2, 1595, 
