65 
of Edinburgh, Session 1866-67. 
proper place in the coloured bands ; — that these bands move over 
the surface of the film under the influence of gravity, and may be 
blown into fragments or into molecules of all colours, or even 
recombined with the film ; that they may be blown into two 
systems of coloured rings, the one revolving from right to left, 
and the other from left to right ; and that under the influence 
of the centrifugal force, these molecules are carried into their 
place in Newton’s scale — those of the first orders going to the 
centre of the rings, and followed by those of higher orders that 
happen to be in the film when it is blown upon through a tube in 
the direction of a diameter. 
“ It is impossible,” the author adds, “ to convey in language an 
adequate idea of the molecular movements, and the brilliant chro- 
matic phenomena exhibited on the soap films, and it is equally 
impossible for art to delineate them. The visible secretion of a 
colourless fluid from a film less than the twelve thousandth of an 
inch in thickness, — its separation into portions of every possible 
colour, — the quick passage of these portions into bands of the differ- 
ent orders in Newton’s scale, — their ever varying forms and hues 
when the bands either break up spontaneously, or are forcibly 
broken up, — their conversion into revolving systems of coloured 
rings under the influence of a centrifugal force, — their various 
motions when the film is at rest, and protected from aerial cur- 
rents, —their recombination into a colourless fluid when driven to 
the centre or margin of concave and convex films, and their re- 
absorption by the film by means of mechanical diffusion, are facts 
constituting a system of visible molecular actions, of which we 
have no example, and nothing even approaching to it in Physics.” 
2. On the Musculus Sternalis . By William Turner, M.B., 
Demonstrator of Anatomy. 
In this paper the author described the results of his observations 
on the presence of the musculus sternalis in upwards of six hun- 
dred bodies dissected in the anatomical rooms of the University of 
Edinburgh. He had found it in nineteen individuals, i.e ., in about 
3 per cent, of the bodies examined. It occurred nearly equally in 
the two sexes. It bore no relation to the general muscularity of 
the individual. In eleven subjects the muscle was single, in eight 
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