1890.] On a second Occurrence 



of Silver in Volcanic Dust 217 



Rutley, Frank, F.G.S. 



Sankey, Matthew Henry P. R., 



Capt. R.E. 

 Saunders, Howard, F.L.S. 

 Scott, Alexander de Courcy, 



Major- General R.E. 

 Seebohm, Henry, F.L.S. 

 Sharp, David, M.B. 

 Shaw, William Napier, M.A. 

 Smith, Willoughby. 

 Stebbing, Rev. Thomas Roscoe 



Rede, M.A. 

 Stevenson, Thomas, M.D. 

 Sutton, J. Bland, F.R.C.S. 



Teall, J. J. Harris, M.A. 

 Thompson, Professor Silvanus 



Phillips, D.Sc. 

 Thorne, Richard Thorne, M.D. 

 Thorny croft, John Isaac, M. Inst. 



C.E. 



Tizard, Thomas Henry, Staff- 

 Commander R.N". 



Veley, Victor Hugo, M.A. 



Waller, Augustus D., M.D. 



Weldon, Walter Frank Raphael, 

 M.A. 



Whitehead, Charles, F.L.S. 



The following Papers were read : — 



I. "On a second Case of the Occurrence of Silver in Volcanic 

 Dust, namely, in that thrown out in the Eruption of 

 Tunguragua in the Andes of Ecuador, January 11th, 188b'.' r 

 By J. W. Mallet, F.R.S., V.P.C.S., University of Virginia. 

 Received February 7, 1890. 



In a paper laid before the Royal Society three years ago,* I gave an 

 account of a specimen of volcanic dust, or so-called ash, from the 

 eruption of Cotopaxi of July 22nd and 23rd, 1885, in which ash 

 silver was found to be present in minute quantity, that being the first 

 instance in which this metal had been detected among the materials 

 ejected from volcanoes. The specimen was sent me by my friend and 

 former pupil Senor Julio R. Santos, of Bahia de Caraguez, Ecuador. 



In his letter accompanying it, dated March 8th, 188(5, he said, " On 

 the 11th and 12th of January there was a terrific eruption from 

 Mount Tunguragua. It is more than a century ago since the last 

 eruption of this volcano." I requested Senor Santos to procure for 

 me if possible some of the ash from this unexpected outburst of 

 Tunguragua, which he kindly promised to do, and at once took steps 

 for the purpose, but his own absence from home and protracted stay 

 at Panama delayed the matter, and only in the early part of the 

 present year (1889) did the specimen reach me. 



In sending it, on the 8th of February last, he wrote to me that 

 "it was collected in Guayaquil on the 11th of January, 1886, on 

 sheets of clean cloth, by Senor Ancisar Montalvo . . . Mount 

 Tunguragua had been silent for over a century; on the 11th of 



* See < Roy. Soc. Proc.,' vol. 42, 1887, p. 1. 



Y 2 



