ATOMIC WEIGHTS 273 



THALLIUM. 



The atomic weight of this interesting metal has been fixed by the re- 

 searches of Lamy, Werther, Hebberling, Crookes and Lepierre. 



Lamy and Hebberling investigated the chloride and sulphate; Wer- 

 ther studied the iodide; Crookes' experiments involved tlie synthesis of 

 the nitrate. Lepierre's work is still more recent, and is based upon 

 several compounds. 



Lamy ' gives the results of one analysis of thallium sulphate and three 

 of thallium chloride. 3.423 grammes of TI2SO4 gave 1.578 grm. BaSO^; 

 whence 100 parts of the latter are equivalent to 216.920 of the former. 



Hence Tl = 205.14. 



In the thallium chloride the chlorine was estimated as silver chloride. 

 The following results were obtained. In the third column I give the 

 amount of TlCl proportional to 100 parts of AgCl : 



3.912 grm. TlCl gave 2.346 grm. AgCl. 166.752 



3.000 " 1.8015 " 166.528 



3.912 " 2.336 " 167.466 



Mean, 166.915, ± .1905 



Hence Tl = 203.79. 



Hebberling's ^ work resembles that of Lamy. Eeducing his weighings 

 to the standards adopted above, we have from his. sulphate series, as 

 equivalent to 100 parts of BaSO^, the amounts of TLSO^ given in the 

 third column : 



1.4195 grm. TLSO4 gave .6534 grm. BaSO,. 217.248 



1.1924 " .5507 " 216.524 



.8560 " .3957 " 216.325 



Mean, 216.699 

 Hence Tl = 204.89. 



Including Lamy's single result as of equal weight, we get a mean of 

 216.754, ±.1387. 



From the chloride series we have these results, with the ratio stated 

 as usual : 



.2984 grm. TlCl gave .1791 grm. AgCl. 166.611 



.5452 " .3278 " 166.321 



Mean, 166.465, ± .097 

 Hence Tl = 203.15. 



1 Zeit. Anal. Cheni., 2, 211. 1863. 

 =* .\nn. Chem. Pharm., 134, 11. 1865. 



