Arsenic associated with Antimony and Tin. 



385 



(l 

 (2 

 (3 

 (4 

 (5 

 (6 

 (» 



(9 

 (10 



(11 

 (12 

 (13 

 (14 

 (15 



Arsenic 



taken as 



H 3 3 AsO. 



grin. 



o-oooi 



0-0033 

 0-0050 



o-oioo 

 o-iooo 



0-0050 



o-oooi 



0-0100 



o-oioo 



o-oooi 



o-oioo 



o-oooi 



o-oioo 



Antimony 



taken as 



H 3 3 SbO. 



grm. 



o-oooi 



0-0001 

 0-4 

 0-4 



Tin 



taken as 



SnCl 4 . 



°rrm. 



o-oooi 

 o-oooi 



0-0005 



0-0005 



0-5 



0-5 



Precipitation 

 by H 2 S in 

 successive 

 distillates. 



I. Found. 

 II. None. 



I. Found. 

 II. None. 

 I. -III. Found. 



IV. None. 

 I-IY. Found. 



V. None. 

 \ I- VII. Found. 

 \ VIII. None. 



I. None. 

 j I-IV. Found. 

 \ V. None. 

 \ I. Found. 

 1 II. None. 

 J I-IV. Found. 

 I V. None. 



I. None. 

 j I-IV. Found. 

 1 V. None. 

 \ I. Found. 

 | II. None. 



I-IV. Found 

 V. None. 

 I. Found. 



II. None. 

 I-IV. Found. 

 V. None. 



Precipitation 



by H 2 S in 



the residue 



dissolved in 



water. 



None. 



None. 



None. 



None. 



None. 

 Distinct color. 

 Distinct color. 



Large. 



Large. 

 Distinct color. 

 Distinct color. 



Distinct. 



Distinct. 



Large. 

 Large. 



It is plain that a single distillation, which may easily be 

 completed in five minutes, is sufficient to discover the presence 

 of 0-0001 grm. of arsenic associated with so much as 0*4 grm. 

 or - 5 grm. of antimony or tin. 



It is also evident that amounts of arsenic not exeeeding 

 0-003 grm. may be completely removed from the residue by a 

 single distillation. When larger amounts of arsenic are to be 

 removed, so that the tin and antimony may be obtained free 

 from that element, the result may be accomplished by repeat- 

 ing the distillation sufficiently ; or, inasmuch as only a little 

 iodine remains after the first distillation, the end may be 

 attained by dissolving the residue in hydrochloric acid of half- 

 strength, bleaching the iodine with exactly the necessary 

 amount of sulphurous acid or sodium thiosulphate (since the 

 use of the stannous chloride is here precluded), and passing- 

 hydrogen sulphide. 



