1350 
(Trans. Chera. doe. (1913), 103 , 1 554) have atfacked the same problem 
and have ohserved tliat the reduction of mercnric chloride by sodinm 
formate is a reaction of the second order and as the complete re- 
action appears to be i-epi-esented by the equation 
2 HgCU + NaCHO., = 2 HgCl + NaCl + HCl -f CO, 
and it follovvs that the reaction innst take place in stages. 
It has now been fonnd out that light accelerates the reduction 
of mercnric chloride by formic acid i.e. more mercurons chloride 
is formed in light than in darkness. 
Formic acid and mercunc chloride at 30°. 
Quality of light 
Time of 
reaction 
HgCl formed 
in grams 
Volume of Solution 
1) Sunlight 
150' 
0.02361 
} 20 c.c.^HgCl2and20c.c. 
Darkness 
150' 
0.01886 
j 3.87 Normal formic acid. 
2) Sunlight 
123' 
0.02006 
1 Do 
Darkness 
123' 
0.01486 
3') Sunlight 
195' 
0.06095 
^ 20 c c. ^HgChand40c.c. 
Darkness 
195' 
0.04825 
) 3.87 Normal formic acid. 
4) Diffused light 
125' 
0.01732 
) 20c.c.:j^HgCl2and20c.c. 
Darkness 
125' 
0.01512 
) 3.87 Normal formic acid. 
5) Diffused light 
155' 
0.02013 
f Do 
Darkness 
155' 
0.01895 
) 
The estimalion of mei-curous chloride was carried out according 
to the method of Kastlk and Beaty (Amer. Chem. Jour. 24 , (1900), 
182). The precipitate of Calomel was decomposed by boiling sodium 
hydroxide solution 
2 HgCl 4 2 NaOH Hg,0 4- 2 NaCl 4 H,0 
and the mixture is fdtered through an asbestos filter and the filtrate was 
exactly neutralised with HNO 3 ‘li© chloridion (CTj was estimated 
with deci-normal or centi-normal silver nitrafe using potassiura chro- 
mate as an indicator. The accuracy of this method was fii’st determined 
by gravimetric analysis and in all cases concordant results were obtained. 
Mercuric chloride is slowly reduced by sulphurous acid and at 
about 30°, the reduclion is quile measurable. The reaction takes 
place according to the following equation: 
2 HgCl, 4 H,S03 + H,0 2 HCl + H,S(), + 2 HgCl. 
It has been found out that the reduction is markedly accelerated 
by light as is evidenced from the following table : 
