274 Transactions of the Society. 
which seem to possess, in a greater or less degree, the qualities above 
mentioned. 
1. Meta-cinnamene, or meta-styrol (formula of molecule, C 8 H 8 ). 
This is a body obtained by Blyth and Hofmann in 1845,* from 
cinnamene, the essential oil prepared by distillation of styrax, a 
substance used occasionally as a mounting medium itself. When 
cinnamene is either (a) exposed to sunlight for three weeks, or (b) 
heated to 100° C. for three days, or ( c ) heated in a sealed tube to 
200° C. for half an hour, it is converted, without change of chemical 
composition, into a polymeric form, a transparent, glass-like solid, viz. 
meta-cinnamene. The specimen I exhibit was prepared by the last- 
mentioned method, and retains the shape of the tube in which it was 
made. It is quite colourless and transparent, permanent under all 
ordinary conditions, and without the slightest tendency to crystallisa- 
tion even after twelve years’ keeping. It is remarkably tough, like 
horn, at ordinary temperatures, but is softened by a moderate heat, 
becoming flexible like gutta-percha, but not a viscous fluid like Canada 
balsam, except at a temperature slightly above 200° C., at which it 
begins to volatilise and change back into the liquid form, — ordinary 
cinnamene. It shows no considerable adhesiveness to glass, and its 
coefficient of expansion differs so much from that of glass that a 
layer of it spread, while hot, upon a glass plate separates from it on 
cooling. In order to determine its refractivity, I constructed a small 
hollow prism of brass, open at the top, with sides of thin glass plates, 
and having a refracting angle of 51° 7' 0". This was heated in an 
air-bath, and some meta-cinnamene was placed in it, the heat being 
raised until the body melted down into close contact with the sides 
of the prism. The angle of minimum deviation for several rays 
was then determined by a spectrometer, and the indices of refraction 
calculated by the usual formula. Thus the index of refraction for 
yellow sodium light (Fraunhofers line D) was found to be 1*597 
(at 15° C.). This is decidedly higher than that of most other resins ; 
and although meta-cinnamene itself is hardly adapted for a cement 
or mounting material, it is likely to be very useful, from its toughness, 
transparency, and permanency, for giving body and strength to other 
cements, as I shall have occasion to notice further on. 
2. Quinidine (formula of molecule, C20II24N2O2). This is one 
of the group of alkaloids occurring in cinchona bark, and is so 
essentially crystalloidal in character that I never thought of examin- 
ing it until a few weeks ago, when my attention was kindly drawn 
to it by Mr. Lewis Wright and Mr. Nelson. I believe that it has 
pleased and plagued microscopists for several years, the conditions for 
ensuring its permanency in the colloidal form not having been satis- 
factorily made out. 
As ordinarily obtained, quinidine is a hydrated salt (one molecule 
associated with two molecules of water), crystallising in colourless 
* ‘ Memoirs of the Chemical Society,’ ii. p. 334. 
