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XXXVIII. On the presence of Arsenic and Antimony in the 

 sources and beds of Streams and Rivers. By Dugald Camp- 

 bell, Analytical Chemist to the Hospital for Consumption, 

 Brompton*. 



SOME months ago I had a specimen of iron pyrites from coal, 

 or coal pyrites as it is familiarly called, sent to me, to exa- 

 mine for arsenic, and I was somewhat surprised to find in it the 

 quantity of arsenic which I did, arsenic not being generally set 

 forth in the analysis which I have seen of such pyrites, although 

 my own impression was that, if looked for in a proper manner, 

 it would be found. 



Having been informed that the coal associated with this 

 pyrites crops out in the beds of the streams and rivers of the 

 district from which my specimen of coal pyrites was sent, it 

 occurred to me that if the sand from the beds of such streams or 

 rivers were carefully examined, arsenic would be found in it. 



Having obtained a specimen of the sand, after a great many 

 experiments (for I was at first beset with difficulties about the 

 purity of the various materials I used in my examinations, and 

 other causes) I at last succeeded in obtaining arsenic from it in 

 every experiment, and really in notable quantity. 



Besides arsenic, I also got antimony, which I had not ob- 

 served in my coal pyrites, although it may very likely have been 

 there in small quantity. 



The quantity, however, of both the arsenic and the antimony 

 appearing so considerable in this specimen of sand, induced me 

 to think that their occurrence was due to other sources besides 

 the coal pyrites, and led me to the opinion that I should find 

 these metals in the sand from the sources or beds of most streams 

 or rivers in greater or less quantity, depending upon the geolo- 

 gical formation from which such sand had its origin ; and after 

 making several experiments, I found my views confirmed in this 

 respect ; and in every specimen of sand from these sources which 

 I have hitherto examined, I have obtained arsenic, and generally 

 also antimony, and, as I had supposed, in some instances the 

 arsenic was in considerable quantity, in others in small quantity ; 

 but in no instance is its presence in a doubtful quantity. 



I say " generally also antimony/' although it is more than 

 likely that antimony exists in every specimen of sand which I 

 have examined; but the process I followed was especially for 

 arsenic, not for antimony, although, as I have stated, I very often 

 got some antimony at the same time with the arsenic. 



Although I speak of the arsenic being in greater quantity in 

 the one sand than in the other, this is observed as yet only by 

 * Communicated by the Author. 



