ANTIMONY. 201 



(6.) K^Cr^O- : tartar emetic : : loo : 337.30, ± .29 



(7.) Ag : SbClj : : 100 : 70.512, ± .021 



(8.) AgCl : SbClg • : 100 : 53.2311, ± .008 



(9.) Ag : SbBrg : : loO : 111.114, rb .0014 



(10.) AgBr : SbBr3 : : lOO : 63.830, ± .008 



(11.) Agl : Sblj : : lOO : 71.060, ± .023 



Three of these ratios give estimates for the molecular 

 weight of antimony trichloride, and two give correspond- 

 ing values for the bromide. These values may be combined, 

 as follows : First, for the chloride we have — 



From (3) SbClg =^ 227.094, ± .115 



" (7) " = 227.771, ± .091 



(8) " = 228.433, ± .039 



General mean " = 228.225, i '034 



Hence Sb = 122.115, ± .055. 

 For the bromide we get : 



From (9). SbBr3 = 358.926, ± .032 



" (10) " = 358.935, dz .060 



General mean " = 358.929, rb .029 



Hence Sb = 119.625, ± .063. 



From all the data eight values for Sb may be deduced. 

 These fall into two groups ; the one near the number 120, 

 the other not far from 122. In making the calculation the 

 atomic weights found in previous chapters are applied ; 

 the value selected for chromium being that deduced from 

 Siewert's experiments : 



1. From Sb2S3, ratio (i) Sb == 120. 145, ± 



2. " SbBr3 " = 119.625, dr 



3. " Sbl3, ratio (11) " = 119.665, rfc 



4. " tartar emetic, ratio (6) " = 118.690, ± 



5. " Sb^04, ratio (2) " = 122. 181, rfc 



6. " SbClj " = 122. 115, zfc 



7. " ratio (4) " := 121.798, dr 



8. " " (5) "= 122.053, ± 



Low. 



High. 



General mean " = 121.027, ± 



General mean of values 1 to 4__ " = 119.935, ±1 

 " " 5 " 8_. " = 122.092, ± 



Although the means of the four lower values and of the 

 four higher values are thus shown to be approximately 



