PROCEEDINGS OF SOCIETIES. 55 
scope can be placed under the stage when it is required, but it is 
my present opinion that this will not be a very frequent mode of 
using the instrument. It appears to me that the plan of putting 
it on as an eye-piece would in the majority of cases be most con- 
venient. When you have an ordinary-sized drop that would fall 
from a bottle of any such fluid as aniline-dye, you do not want an 
object-glass at all, as you get its spectrum clearly without. If you 
operate upon a good-sized drop you can do it very well with a 
three inch or two inch power; if you take a very small drop such 
a power as a three inch would be convenient, and with a smaller 
quantity you may work with as high a power as Messrs. Smith 
and Beck’s 35th, or even with Powell’s 25th. I found a very con-— 
venient mode of operation to be, to put a glass stage upon the 
microscope with a rim all round so as effectively to prevent corro- 
sive fluids from running over, and, if I had one made on purpose, 
I should make the bottom rim stick up a little at an acute angle. 
If you take a little piece of glass tube and draw it out to the size of a 
needle and turn it round the corner, like the crook of an umbrella, 
you can hook up a small quantity of fluid and transfer to the glass 
stage a drop so small as to have no chance of falling down, and 
which will yet last several minutes without disappearing from 
evaporation. JI find that in this way a series of minute experi- 
ments could be carried on with great facility. The union of 
spectroscope with microscope opens a most interesting range of 
inquiry, and not the least interesting result, in one point of view, 
will be the getting a better notion of what the colours of certain 
objects really are. It is well known that we can take two solu- 
tions which are very nearly alike to the ordinary eye and are 
perhaps undistinguishable by it, and yet the spectroscope dis- 
criminates them at once. I apprehend that when we view an 
object—a transparent or an opaque one, as the case may be—the 
spectroscope shows us precisely what our eyes would show us if 
they were more exact; and it is interesting to know exactly what 
rays are deficient in particular colours, and also to see how the 
application of small quantities of different reagents can effect 
such molecular or chemical changes as to change the spectrum. 
Mr. Slack did not know, when making those observations, that 
some of the new spectroscopes were in the room. 
The PrestpEntT announced that several microscopes to which 
the Sorby-Browning principle was applied were in the room for 
the inspection of the members. 
Mr. Lozs gave an account of a vacation visit to Oakshott, near 
Leatherhead, in Surrey, and to Keston, near Bromley, in Kent. 
At Oakshott he had found in a spring on the heath great abun- 
dance of Closteria, with scarcely any admixture of other genera. 
The gathering was exceedingly pure. At Keston he had obtained 
Desmidiacee of almost every genera and species figured in Ralfs : 
among them he had discovered what he thought was a new species 
either of Cosmarium or Staurastrum ; there was, however, a diffi- 
eulty in deciding which. The frond has conic spmes round the 
