184 THE ATOMIC WEIGHTS. 



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 the 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 Tl^SO^ gave 1.578 grm. BaSO^ ; 

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

 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 I'lCl 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, zh .1905 



Hebberling'sf work resembles that of Lamy. Reducing his weighings 

 to the standards adopted above, we have from his suli)hate series, as 

 equivalent to 100 parts of BaSO^, the amounts of Tl.SO^ given in the 

 third column : 



1. 4195 grm. TI2SO4 gave .6534 grm. BaSO^. 217.248 



I. 1924 " .5507 " 216.524 



.8560 " .3957 " 216.325 



Mean, 216.699 



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

 216.754, d= .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 



Lamy's mean was 166.915, ± .1905. Both means combined give a 

 general mean of 166.555, ri= .0865. 



AVerther's;}: determinations of iodine in thallium iodide were made by 

 two methods. In the first series Til was decomposed by zinc and potas- 

 sium hydroxide, and in the filtrate the iodine was estimated as Agl. 



*Zeit. Anal. Chem., 2, 211. 1863. 

 t Ann. Chem. Pharm., 134, 11. 1S65. 

 J Journ. fiir Prakt. Chem., 92, 128. 1864. 



