268 Mr. Vivian on the Process of Amalgamation [April, 



the meta! being oxidized, or from its particles, finely dissemi- 

 nated, becoming intimately mixed with the particles of water. 

 In this last case the foam should be left to settle, when the 

 quicksilver will collect together. The waste from the vats is 

 coriducted through underground gutters out of the works, and 

 received in pits. In these the earthy matter is allowed to 

 subside, and the saline solution is drawn off to be employed 

 elsewhere. As a check on the operation in the works, the 

 deposit which is received into the waste pits should be occa- 

 sionally assayed for silver, as well as examined for particles of 

 mercury. The contents of the waste pits are thrown from 

 thence into the river, and carried off by the first flood. I 

 believe it is the custom at Freyberg to assay the residue from 

 each vat, and I understood it usually contains a small portion of 

 silver; perhaps from -^ to 4 of a hth in the centner. 



1 recollect its being mentioned to me in 1816 as a singular 

 circumstance, that the ten barrels on the north side of the amal- 

 gamation-room invariably yielded a cleaner residue than those 

 on the south side, although the charges and treatment were in 

 every respect the same. As I felt incredulous as to the correct- 

 ness of this assertion, I exammed the assay books at the works; 

 and it certainly did appear as stated, that the residuum from the 

 barrels on the south side contained invariably a small quantity 

 of silver more than those on the north side. 



It now only remains for me to make a few remarks on the uses 

 to which the saline solution drawn off from the waste pits may 

 be applied. Various experiments have been made with a view 

 to ascertain the most advantageous mode of using this liquid. 

 It has been sometimes applied to the preparation of manure, by 

 decomposing the sulphate of soda with lime, and thus forming 

 an insoluble salt, or artificial gypsum: and it was remarked to 

 me by Prof. Lampadius, that the action of this salt as a manure 

 appeared to be increased by the iron precipitated fropi the mu- 

 riate, by its acid uniting with the soda of the Glauber salt, which 

 becomes highly oxidized by exposure to the atmosphere. During 

 my last visit to Freyberg, Prof. Lampadius was engaged in some 

 experiments for applying the sulphate of soda, obtained by 

 evaporation, to glass-making, instead of potash ; and from some 

 specimens of white glass, &c. showed me, it appeared that the 

 experiment might possibly be successful. 



The general arrangement of the interior of the principal 

 building of the Freyberg amalgamation- work may be collected 

 from the description given of the different processes; from 

 which it will appear that much labour and expense may be saved 

 by facilitating the communications between the different parts of 

 the works. By means of a shaft and machine for raising the 

 ore to the different stories of the building, and apertures in the 

 floors for letting it down, as it may be required ia the different 



