by Sodium Thiosulphate. 



51 









Table 



III. 









HgCl 3 



Volume 







HgCl 2 







taken 



at 



Tem- 



Na 2 S. 2 3 



found 







as Hg. 



beginning. 



perature. 



in excess. 



as Hg. 



Error. 





grams. 



cm 3 . 



C. 



cm 3 . 



grams. 



grams. 



1. 



0-0749 



50 



70° 



4-15 



0-0751 



0-0002 + 



2. 



0-0749 



50 



75 



0-72 



0-0728 



0-0021 — 



3. 



0-0756 



50 



72 



1-46 



0-0759 



0-0003 + 



4. 



0-0753 



50 



70 



2-57 



0-0750 



0-0003 — 



5. 



0-0390 



50 



70 



3-43 



0-0395 



0-0005 + 



6. 



0-0388 



50 



72 



8-19 



0-0390 



0-0002 + 



7. 



0-0380 



50 



76 



2-03 



0-0393 



0-0013 + 



8. 



0-1494 



50 



78 



4-99 



0-1498 



0-0004 + 



9. 



0-1489 



150 



78 



4-38 



0-1512 



0-0023 + 



10. 



0-1480 



50 . 



70 



52 



0-1438 



0-0042— 



11. 



0-1498 



50 



78 



1-47 



0-1540 



0-0042 + 



12. 



0-1484 



50 



71 



2-09 



0-1517 



0-0033 + 



13. 



0-1480 

 HgCl 2 



75 



Volume 



72 

 Table 



1-59 



IV. 



0-1509 

 HgCl 2 



0-0029 + 





taken 



at 



Tem- 





found 







as Hg. 



beginning. 



perature. 



NajSaO, 



as Hg. 



Error. 





grams. 



cm 3 . 



C. 



in excess. 



grams. 



grams. 



1. 



0-0759 



100 



60° 



3-06 



0-0766 



0-0007 + 



2. 



0-0384 



u 



u 



2-81 



0387 



0-0003 + 



3. 



0-1498 



a 



u 



1-1 



0-1500 



00008 + 



4. 



0-1503 



a 



a 



1-63 



0-1506 



0-0003 + 



5. 



0-1479 



u 



u 



2-41 



0-1480 



0-0001 + 



6. 



0-1489 



a 



cc 



2-12 



0-1503 



0-0014 + 



7. 



2244 



te 



a 



2-63 



0-2259 



0-0015 + 



8. 



0-1490 



u 



a 



2-33 



0-1484 



0-0006 — 



9. 



0-0758 



a 



a 



2- 



0-0762 



0-0004 + 



10. 



0-0383 



a 



u 



2-58 



0-0379 



0-0004 — 



From this table it is plain that Scherer's process for the 

 estimation of mercury in the form of mercuric chloride is 

 capable of yielding accurate results if carried out under certain 

 fixed conditions. These conditions, which must be closely 

 adhered to, are as follows : The solution containing the mercury 

 in the form of mercuric chloride is placed in a liter flask, 

 diluted to 100 cm3 and heated to a temperature of 60° C. The 

 sodium thiosulphate in -^th normal solution is run in from a 

 burette until the white precipitate formed begins to take on a 

 brownish tinge. The solution is then diluted with cold water, 

 some asbestos fiber added to coagulate the precipitate and the 

 whole is quickly thrown on the filter. After careful washing 

 of the precipitate, the filtrate is diluted to a definite volume, 

 3 grams of potassium iodide added and the excess thiosulphate 



