36 Mr. Children on the Characters of some [July, 



weights of silver, antimony, and sulphur, as determined by Dr. 

 Thomson, for the more complex numbers employed by Bonsdorf 

 in the preceding calculations. 



The atom of silver weighs 13*75 



antimony 5-5 



sulphur 2*0 



Red silver ore is a compound of 1 integrant particle of sul- 

 phuret of silver and 1 integrant particle of sulphuret of anti- 

 mony. Sulphuret of silver is composed of 



1 atom silver 13*75 



1 atom sulphur 2*0 



15-75 

 Sulphuret of antimony of 



1 atom antimony 5*5 



1 atom sulphur 2-0 



7-5 

 Hence the constituents of red silver are: 



1 atom silver 13-75 or 59*14 



1 atom antimony 5*50 23*65 



2 atoms sulphur 4*00 17*2 1 



23*25 100*00 



The numbers in the last column are exceedingly near the 

 result obtained by Bonsdorf. Indeed, if the loss in his analysis 

 was sulphuret of antimony, as is exceedingly likely, the theoretic 

 numbers almost coincide with those derived from the analytical 

 experiments. 



Ahticte VI. 



On the Characters of some Mineral Substances before (he Bloiv- 

 pipe. By J. G. Children, FRS. ike. 



Thk blowpipe, when skilfully handled, is the most convenient 

 chemical instrument for mineralooical researches on a small 

 scale that has hitherto been invented. By its means we are 

 enabled in a few minutes to determine the principal ingredients 

 in any mineral submitted to our examination, even though it be 

 composed of several elements. By merely directing the flame 

 of a small lamp on a fragment about half the size of a pepper- 

 corn, supported on a piece of charcoal, or in the platina forceps, 

 most of the volatile substances, as sulphur, arsenic, zinc, cad- 

 mium, antimony, bismuth, and tellurium, may be detected ; 



