496 
ON THE COHESION FIGURES OF LIQUIDS. 
March, in these new glasses. They were not made nnder very favourable cir¬ 
cumstances, as the temperature of the room was under 50° ; whereas it should 
not have been less than about 60°. Two specimens of East India castor oil 
supplied by an importer were tried. The first, a colourless, viscid oil, gave a 
good figure, though small, probably due to the low temperature. The second, 
which had a slight tinge of brown, gave a good figure, rather larger than the 
first. Two other oils from the same house also furnished capital figures. 
Three other specimens were furnished by Messrs. Baiss, Brothers. The 
first, East Indian, a bland, viscid, colourless oil, produced an admirable figure. 
The second, Italian, prepared “ from the finest decorticated seeds,” was a 
sweet, bland oil, and gave even a still finer figure, the coloured rings being 
very persistent. The third, which has been in my possession nearly three 
years, and produced the figure from which my description and large diagram 
were taken, is still as good as ever. An oil, bought about the same time at 
a druggist’s, produced a figure by no means so good ; it did not open so freely, 
nor were the colours so bright as with the finest oils, but the residual figure 
was good, and I am not able to say but that it was a pure oil. 
A specimen from the Jamaica Court of the International Exhibition was 
of a yeUow-brownish colour ; the taste rather acrid. The coloured rings of 
the figure were finer than in the former specimens, but the lace-like border 
was not so well developed, and the perforations were smaller. 
Another specimen from the Italian Court of the International Exhibition, 
gave an admirable figure ; it opened well with very persistent colours. The 
silvery corona also opened into innumerable small well-shaped circular holes 
before the lace-like pattern was developed. The outer coloured rings were 
also perforated. 
A specimen from the India Museum, a colourless oil, gave an exquisite 
figure: another, from the same source, an opaque specimen of a yellowish 
colour, gave a very small figure, only about half the usual size; the residual 
figure was not like that of the other specimens, and it soon gathered itself up 
into a small disk. 
I am not sufficiently acquainted with the commercial treatment of castor 
oil to make any remarks on the change of figure likely to arise therefrom, but 
I give these details respecting a dozen specimens from different parts of the 
world to show how constant is their behaviour in the production of a charac¬ 
teristic cohesion-figure. 
Fig. 8 is a portion of the Balsam of Copaiba figure. I had only three specimens 
of this balsam to operate on. The first, which is two or three years old, from 
a wholesale house in the City, gives a splendid figure, consisting of large irides¬ 
cent disks apparently growing out from under each other and quickly sub¬ 
siding into a colourless disk with a sharp well-defined edge, just within which 
appears a string of very minute bosses, which it requires a sharp eye to detect. 
In the course of ten or fifteen minutes the film does not open into holes, as 
many films do, but becomes dotted over with pit-like depressions, which en¬ 
large, and gradually the base of each pit opens into a minute network. These 
particulars I did not stop to describe at the meeting, but they are given in 
m} r original description of the figure. 
A second specimen, of a brownish colour, gave a very good figure, though 
not quite so large as that of the first, but it behaved in all respects like it. A 
third specimen, much more fluid than the above,* shot out rapidly with much 
less development of colour, and often without any colour at all. The film 
* The specimens Nos. 2 and 3 were in long narrow bottles, nearly full. , A rough measure 
may be given of their comparative viscidity when it is stated that on inverting No. 2, the 
bubble of air under the cork reached the other end while 8 was counted; in No. 3 it travelled 
through the liquid while counting 2. 
