1896.] 



Mc 



cliloride. 



85 



mercuric oxide. ^ Sometimes, however, chlorine and a hypochlorite by 

 their mutual decomposition form free hypochlorous acid.2 This acid 

 combines with mercury and forms mercuric oxychloride, a substance 

 as insoluble in water as mercurous chloride. When, therefore, such a 

 solution, containing mercurous chloride, mercuric oxide or oxychloride, 

 free mercury, and soluble chloride and chlorate, is filtered, the first 

 three remain on the filter paper. The residue is then thoroughly 

 washed and then treated with the least excess of dilute hydrochloric 

 acid and the residue of mercurous chloride and free mercury thoroughly 

 washed. The quantity of mercury existing as mercuric chloride in the 

 second filtrate^ will give the amount of hypochlorous acid. Free 

 chlorine is represented by mercurous chloride. The chlorine of the 

 last named substance is generally estimated by decomposing the comT 

 Action of cold alkali on Po^^d after gentle digestion with alkali 

 mercurous chloride. hydrate (fixed).* Some volumetric determina- 

 tions having given tolerably accurate results,^ the following analyses 

 were made to see whether the decomposition is complete or not. The 

 sample of chloride was first treated with hot water and then repeatedly 

 with cold water and finally with rectified spirit in the filter pump. It 

 was then dried in the steam bath for two hours when its weight was 

 found constant. Absence of any soluble mercury salt was proved by 

 treating a small quantity with hob water and passing sulphuretted 

 hydrogen through the filtiate. 





Wt. of 



Wt. of 

 AgCl. 



Corres- 







No. 



HgCl 



ponding 



7o of CI. 



Remarks. 





grams. 



chlorine. 







D. 



1-5600 



.. 



•230O 



14-75 



Excess of Ag NO3 adcl-d and 

 titrated by Vohlard's method. 



E. 



31958 



1-9358 



•4805 



15-02 



Gravimetric metliod. 



F. 



2 2351 



1-3577 



•3358 



15 02 



„ „ (Gooch's 

 crucible). 

 Gravimetric method (Gooch's 



G. 



1-9444 



1-1800 



•2919 



15-02 













rrnriblel. 



1 According to the following equation : — Na Cl + Hg = Hg + Na CI. 



8 The reaction is most probably Na (0 Cl}+ Cl^ + H„0 = NaCl -1-2H0C1. (S. C. J. 

 1885, 722). 



8 For HgO, HgCl2 + 2EiCl. = 2HgCl2 + H2 0. 



* Watt's Die. Chem. (new edition) Vol. iii. p. 316. Fresivius, Quant. Anal. 

 7th Ed , p. 360. Fremy in his Encycl. Chem. does not mention anything. 



^ For these I am indebted to my elder brother, Babu Chandrabhushan Bhadnri, 

 B.A. The silver solution was weaker than it was supposed to be, so the value of 

 chlorine was very near the truth. On recalculation the difference is found to be 

 about 2 per cent. 



