498 Dr. Kane’s Experiments on White Precipitate. 
hitherto advanced, oxygen is enumerated as a constituent toa 
very considerable amount, generally so much as to peroxidize 
the whole of the quicksilver. ‘The results hitherto obtained 
in my experiments would not appear to leave room .for so 
much oxygen, and I therefore endeavoured to obtain an esti- 
mate of the amount by direct experiment, on the following 
principle. When white precipitate is heated, there is obtained 
ammonia and azote, water and calomel, but no free oxygen. 
Therefore all the oxygen of the substance has been formed 
into water at the expense of the ammonia, and by collecting 
the water and determining its weight, the quantity of oxygen 
present could be ascertained. A small retort was blown of 
strong glass and a capacity of from 0-2 to 0°3 of a cubic inch; 
the neck being about two inches long. ‘To this was tightly 
connected a small tube containing fused potash, and commu- 
nicating by a small tube with the mercurial trough. The re- 
tort was carefully weighed and the white precipitate intro- 
duced, then weighed again. ‘The desiccating tube was care- 
fully weighed, and the apparatus having been connected 
tightly, heat was applied until the chlorine and mercury had 
all sublimed as calomel. ‘The water was driven over com- 
pletely into the potash tube, and the mixed azote and ammo- 
nia collected over mercury and analysed by water; the cor- 
rections for temperature and pressure, air of apparatus, and 
residual gas having been attentively applied. After the opera- 
tion the retort was weighed. The residue was calomel, the 
loss water and gases. The desiccating tube was weighed ; 
the increase of weight was water. ‘There were obtained in 
four experiments the following quantities of water: 
Material. Water. Water per cent. 
22:21 0:22 0-990 
20°47 0:14 0°684 
12°14 0:08 0°658 
19:42 0-00 0-000 
Giving a mean of 0°583 per cent, of water. 
Summing up all the means we obtain a final result for the 
composition of white precipitate, viz. 
Mercury: )....¢=-ns00.. = ,,78°60 
Chlorine ........00.. = 13°85 
ATMO Aresacsvcs sss ees ONC 
WY difeiastasaricettdaces c= Opos 
DL O08 wenvarsscmneles cde =) OECD 
100:00 
