Mr Cameron m, a New Power and Apparatus for 
The mean of all these results for the mean temperature of the 
earth at Paramatta in November and December, and probably 
for the whole year, is 61°.5, whereas the mean temperature of the 
atmosphere,, as calculated by Dr Brewster’s formula, is about 
This difference of 1 is nearly the same that exists between the 
temperature of the earth, and the temperature of the atmosphere 
in corresponding latitudes in the northern hemisphere. 
Art. IV . — Description of a New Power^ and Apparatus for 
impregnating Mineral Waters with Carbonic Acid. By Mr 
Charles Cameron, Chemist, Glasgow. Communicated by 
the Author, in a Letter to Dr Brewster. 
The vessel A, Plate VII. Fig. 6., containing about 15 gallons^ 
is formed of cast-iron, |ths of an inch thick, and lined with sheet- 
lead of from 8 to 10 lb. per square foot, having an agitator B 
covered with lead, working on the pivot below and through the 
stuffing-box C. By the opening at D, the vessel is filled up to the 
dotted line with a mixture of whitening and water. The vessel E, 
containing S gallons, is formed of lead, f ths of an inch thick, and 
is filled with sulphuric acid up to the dotted line. The acid is kept 
from falling down into A by the lead-plug F, which is conically 
pointed, and fits into a corresponding conical opening in the lead- 
pipe G The plug moves straight up and down through the stuf- 
fing-box H, and is prevented from turning round by the pin K, 
which moves in a slit in the bridle L, the screw-nut M being rivet- 
ted loose into the top of the bridle. By this means the conical point 
of the plug is preserved from injury, as it is merely lifted out of 
the opening, and again pushed into it. This is more complicated 
than a common formed glass or lead stop-cock, but neither of 
them will answer where a high pressure is applied. The pipe N, 
inserted into the top of the vessel E, and into the pipe S (which 
incloses the plug), preserves the equilibrium of pressure, so that 
the sulphuric acid rises no higher in the pipe S than in E, and 
consequently preserves the brass- work of the stuffing-box. The 
intermediate vessel O, containing 3 gallons, is formed of thick 
lead, or cast-iron lined with lead, and filled with water up to the 
dotted line ; it is employed for retaining any of the sulphuric 
acid, in case it should be carried over by too strong an efferves- 
