givea of specimens of amber containing fish, which were 
evidently manufactured, and not of natural occurrence. The 
author then described his microscopic investigations into the 
cause of the cloudiness in amber, an ap,pearance which was 
due to the presence of an immense number of small cavities, 
of very various shapes, some containing fluid only, others 
probably gas, or even vacuity, and others again were tilled 
with fluid, which had a bubble of gas in it. Mr, H. C. 
Sorby, F.R.S., well known for his researches on the micro- 
scopic structure of crystals, had examined these, and shown 
that several gave a black cross with polarised light, indicat- 
ing a want of pressure, as though the material surrounding 
the bubble had become somewhat solid and contracted, so 
producing a tension. The cloudiness in amber was due, 
therefore, to the intimate and irregular mixture of airorsome 
gas, or even vacuities, with it; other examples of the same 
law of light were seen in pounded rock salt, or the powder 
of any transparent soli-i, clnuds, condensed steam, foam, &c. 
Animi very rarely presented this appearance, nor was it 
probable that any amount of age would produce it. The 
greater number of these cavities were spherical, usually less 
than 1-lOOOth of an inch diameter, and sometimes occurred 
in waves, but occasionally some were met with more or less 
resembling in shape a balloon with car attached. The 
minute structure of these was described, and a comparison 
I instituted with cavities in the diamond, quartz, mellite, and 
I other mineral substances. Reference was then made to the 
organic remains, as insects, &c., found in amber, the action 
of chloroform on it described, and the paper concluded witti 
the inference that amber had remained in a viscous state 
longer than recent resins, and that some specimens under 
dijfferent circumstances were in that condition much longer 
than others. 
The paper was illustrated with several beautiful specimens 
of animi and amber, and with drawin^^s by Mr. Ravis of 
some of the microscopic appearances. Mr. C. O. G. Napier 
also sent specimens of amber from Fezzan, in North Africa, 
where they were used as money, and also some picked up oa 
the beach at Margate, which contained insects. 
The President, in thanking Mr, Butler for his paper, and 
Mr. Ravis for reading it, observed that though the cause and 
nature of these cavities were obscure, he questioned whether 
they had any relation to the cavities and vacuities in quartz ; 
similar ones were found in granite, and many of them con- 
itained water. He also explained that the submerged forests 
ifrom which the Baltic amber was derived belonged to the 
Tertiary period. 
Mr. Leipner believed, on various grounds, that the cars 
attached to the biUooa-shapad cavities were probably 
vacuities — the spherical cavities contdining a gas or fluid. 
Mr. VV. L. Carpenter spoke of the vacuities frequently 
met with in ice, as described by Prof, Tyndall, as well as 
the constant presence of air, which was entangled in it, 
rendering it opaque. He also called attention to the opacity 
in many specimens of ordinary resin, caused by the intimate 
mixture of turpentine, which could be expelled by heat, and 
the resin made clear. As little as 1 per cent, of turpentine, 
equally diffused through the mass, produced this effect, 
Mr. W. W. S'^oddart described the production of balloon- 
shaped cavities in Caoada balsam (also a resin) when heated 
on a glass slide f jr mounting microscopic objects. 
I Mr. C. O. Grooma Napier's paper on the Horse and Man, 
[ which was announced for this evening, was postponed till 
the April meeting, to enable the author to be present, and 
to read it himself. 
j WM. LANT CARPENTER, 
I Hon. Reporting Secretary, 
