198 
POPULAR SCIENCE REVIEW. 
with madder. This practical application by Mr. Perkin of a discovery 
which might otherwise have remained in the laboratory, may be regarded 
as one of the most important chemical events of late years. 
The Constitution of the Ammonium Carbonates. — At the same meeting as 
that above named, Dr. Edward Diver read an important paper on the 
relation of the Ammonia Carbonates and Carbamate. But as the further 
reading of Dr. Diver’s paper was postponed to the next meeting of the 
Society, we must defer an account of it till our July number. 
Absorption of mired Vapours by Charcoal. — Mr. John Hunter of Queen’s 
College, Belfast, who published a paper on the above subject nearly two 
years ago, again brought Jiis views forward at the meeting of the Chemical 
Society on January 20th. In experimenting on the absorption of a mixture 
of two vapours by means of cocoa-nut charcoal, he found that the absorption 
w T as increased when one of the vapours was at a temperature near to its point 
of condensation ; and he explained the phenomenon by assuming that, when 
a fragment of charcoal is introduced into a mixture of two vapours, the one 
which is nearest to its point of condensation is first absorbed, and this, in its 
condensed state in the pores of the charcoal, aids the absorption of the other 
vapour. According to this view, a succession of condensations is going on. 
The theory is strikingly illustrated in experimenting with a mixture of 
water vapour and ammonia gas (obtained by heating an aqueous solution of 
ammonia of sp. gr. 088), when the mixture is much more largely absorbed 
than either the gas or the vapour separately. The mean of a set of experi- 
ments made at 100° and a mean pressure of 706-2 m.m. was 316-6 vols. of 
the mixture absorbed by 1 vol. of charcoal. 
Apparatus for the Analysis of Carbonates. — Dr. C. A. Cameron of Dublin 
described in a recent number of the Chemical News an apparatus for the 
above purpose which he thinks simpler than any other. His apparatus is a 
light bottle, of the capacity of 75 centimetres. The lower part is divided 
into two compartments ; in one of which the carbonate is placed, in the 
other the acid. By inclining the bottle, the aoid may be allowed to flow over 
on the carbonate as gradually as the operator pleases. One or two chloride 
of calcium tubes are inserted through the cork. The cost of this bottle 
would be about 6r/. 
Chemist to the Mint. — Mr. W. Chandler Roberts has been appointed to 
the above office. The post is, we believe, a new one. 
Artificial India Rubber. — Les Monies (February 3rd) contains a description 
of a compound under this name prepared by M. Grainer. This material is a 
mixture containing gelatine and a variety of other substances (not specified) 
producing a homogeneous elastic substance, insoluble in mineral, as well as 
vegetable essential oils ; not acted upon, moreover, by either coal or other 
hydrogenised gases. This material is now employed in France for a variety of 
purposes, too many to be here enumerated ; its cost is only 3 francs per 
kilo. ; and it melts readily at 100°, without decomposition, and can be cast 
into different moulds. Neither cold nor heat affect this substance, which, 
when completely oxidised, becomes more infusible than vulcanised caout- 
chouc. See also Chemical News. 
Chemistry of l'ossil Rones. — The Comptcs rendus for December contains 
an important paper stating the results of several analyses of fossil bones, 
