1123 
Trans. Chem. doe. (1913), 108, 1554) have attacked the same problem 
and have observed that the reduction of mereurie chloride by sodium 
formate is a reaction of the second order and as the complete re- 
action appears to be represented by the equation 
2 HeCl, + NaCHO, = 2 HgCl + NaCl + HCI + CO, 
and it follows that the reaction must take place in stages. 
It has now been found out that light accelerates the reduction 
of mercuric chloride by formic acid i.e. more mercurous chloride 
is formed in light than in darkness. 
Formic acid and mercuric chloride at 30°. 
Time of HgCl formed 
Quality of light Volume of Solution 
reaction in grams 
1) Sunlight 150’ 0.02361 20 cc. 5 HgCls and 20c.c. 
Darkness 150’ 0.01886 j 3.87 Noriral formic acid. 
2) Sunlight 4123) 0.02006 |) 
Do 
Darkness 123’ | (0.01486 | $ 
3) Sunlight 195’ | 0.06095 |) opec” N HgCl, and dee 
Darkness | 195’ |. 0.048% | f 3.87 Normal formic acid. 
4), Diffused light 125’ | _0.01732 | 20 ec. HHC and 20e. 
Darkness 125/ | 0.01512 { 3.87 SoReal formic acid. 
5) Diffused light 155’ | 0.02013 
Darkness 155° 0.01895 | fl a 
The estimation of mercurous chloride was carried out according 
to the method of Kasrrr and Brary (Amer. Chem. Jour. 24, (1900), 
182). The precipitate of Calomel was decomposed by boiling sodium 
hydroxide solution 
2 HeCl + 2 NaOH = Hg,0 + 2 NaCl + H‚C 
and the mixture is filtered through an asbestos filter and dt filtrate was 
exactly neutralised with HNO, and the chloridion (Cl’) was estimated 
with deci-normal or centi-normal silver nitrate using potassium chro- 
mate as an indicator. The accuracy of this method was first determined 
by gravimetric analysis and in all cases concordant results were obtained. 
Mercurie chloride is slowly reduced by sulphurous acid and at 
about 30°, the reduction is quite measurable. The reaction takes 
place according to the following equation: 
2 HeCl, + H,50, + H,O > 2 HCI + H,SO, + 2 HeCl. 
It bas been found out that the reduction is markedly accelerated 
by light as is evidenced from the following table: 
