1127 
Evidently the velocity of reduction of mercuric chloride by pot- 
assium oxalate is very rapid in comparison with other acids and it 
will also be seen that the amount of mercurous chloride formed is 
proportional to the time of exposure. (See table p. 1126). 
Moreover it has been found out that canesugar solution, hydroxyl- 
aminehydrochloride, hydrazine hydrochloride and ferrous sulphate 
can slowly reduce mercuric chloride in presence of sunlight; in 
diffused daylight there is no appreciable reduction. 
| Amount of HgCl 
Volume of solution 50 hours formed in grams 
. M 
11) Cane sugar solution ‚… 50c.c.and 
N 10 50 hours 0.00752 
10 ce. 14 HgCl, ‘| 
50 cc. Molar cane sugar and 10 c.c. | | 
N ' 55 hours 0.02684 
~ HgCl, | 
10 
| 
12) 50 c.c. hydroxylamine hydrochlo- | 
ide 2N (factor 1.128) and 10 c.c. 
Ny aes ae Mea ae 80 hours 0.02175 
Iya ae | 
50 cc. hydroxylamine hydrochlo- | | 
ride = (factor 1.128) and 10 cot 95 hours 0.00435 
13) 50 c.c. 2N (factor 1.156) hydrazine 
N | „02 
hydrochloride and 10 c.c. “HgCh. PEO 0.02915 
N 5 
50rec; ry (factor 1.156) hydrazine | 
N ‘85 hours | 0.00463 
hydrochloride and 10 c.c. qosCh- | 
N | 
14) 50 c.c. 5 Ferrous sulphate and | | 
N | 25 hours 0.02512 
10sec: 10 HgCl,. | 
Do 45 hours | 0.04987 
| 
When a solution of mercuric chloride is boiled even for hours 
together with tartaric acid, citric acid, or any of these reducing 
agents, there is no appreciable reduction but in presence of sunlight, 
only the reduction takes place even at the ordinary temperature. 
Since the velocity of these reduction processes is very slow, these 
changes cannot be used in measuring the chemical intensity of sun- 
light and hence these mixtures cannot serve as photometers. 
73 
Proceedings Royal Acad. Amsterdam, Vol. XVIII. 
