426 Scientific Intelligence. 
If we call the distance from the equator to the pole 6,000 
miles, and suppose the velocity of the surface current toward 
the pole to be only one mile per day, we find from a (16), 
that this would require a head of water at the equator 
h = 195-80 feet. 
such difference of level can be admitted between the equi- 
iiviam levels of the equatorial and polar oceans. The latest 
accurate estimate of the difference is that made by Mr. Croll, 
vizZ., eet. This head of water, if it eould produce an oceanic 
flow at all, would be one at the rate of one mile in 42°567 ays; 
or a flow that would occupy 700 years to pass from the equator 
to the poles. 
SCIENTIFIC INTELLIGENCE. 
I. CHEMISTRY AND PHYSICS. 
1. On the determination of Carbon dioxide in expired air 
Marcet has described a modification of Pettenkofer’s apparatus 
oe determining the amount of carbon dioxide contained in expired 
He uses a cylinder of thick glass, of about two liters capacity, 
ground flat at both ends and re by disks of thick glass, closely 
tting the openings and kept in place by brass collars 
upper glass disk is perforated ii three holes, to contain respec- 
tively a thermometer and two sto oe The lower disk has one 
opening, for the insertion of a pyeock. The cylinder is sup- 
orted ona tripod. The air to be sae ee is collected in a rubber 
ag, those used by Marcet holding 39°3 and 64:8 liters under the 
pressure mak one inch of water. The bag is connected to the cyl- 
inder by one of the upper openings, ge the cylinder is put in 
SoGininibation with the air-pum e lower one. After ex- 
hausting to 20 or 30 mm. pressure the air from the bag i is allowed 
to enter the cylinder; this Speration being repeated till the cylin- 
der is filled with air from the ba y means of the thermometer 
solution. On patie the fre nerd of the pipette and the i 8 
necting tube, the solution passes into the spades After a 
- the milky liquid is drawn off into a 100 e.c. bottle and claealy 
ed. Subsequently, at convenience, 25 e.c. of this liquid A 
aed with a pipette, 100 c.c. of distilled ute on is added, t 
solution is placed in a burette and added to 5 c.c. of an sat 
acid solution of such strength that 1 ¢.c, pubs i to one milli- 
