426 Proceedings of Royal Soeiety of Edinburgh. [jult 2? 
— 30 to 45 minutes— -pink, opaque, and uncoagulated. The cor- 
puscles when examined were all rounded in shape. 
Drops placed for the purposes of comparison on glass slides 
coagulated in five minutes, and became dark in colour. 
In this case, therefore, we must suppose that the corpuscles are 
mechanically stimulated by solid matter causing them to throw out 
processes. 
According to Mr Geddes, the plasmodium of shed blood exhibits 
for some time curious evidences of vitality, all of which, however, 
we have not been able to verify in the case of the crab’s blood. 
The individual corpuscles remain alive, however, for some time after 
coagulation is complete, except perhaps those which have touched, 
and actually remain in contact with, solid matter. In a microsco- 
pical preparation, the cells which are in contact with the slide spread 
out to form a branching film, and after about ten minutes we found 
it impossible to say whether or not they were still living. Cells 
lying above them, and not permanently in contact with the glass, 
continued to change their shape for some time longer. 
6. On Laplace’s Theory of the Internal Pressure in 
Liquids. By Professor Tait. 
{Abstract.) 
Laplace, assuming molecular force to be insensible at distances 
greater than a small quantity a, finds the resultant molecular force 
on a unit particle at a distance x within the (plane) surface. This 
being called X, the internal pressure is 
where p is the density of the liquid. But this is evidently the 
work required to take unit volume of the liquid (particle by 
particle) from the interior to the surface. And it is easily seen 
that to carry it from the surface beyond the range of the molecular 
forces requires just as much more work : — for the density of the 
surface-film is treated as equal to that of the rest of the liquid. 
It is suggested by my experiments that the molecular pressure in 
water at 0° C. may be about 36 tons’-weight per square inch. 
