1866. ] Chemistry. 267 
or a few drops of ether. The tube being filled with the gas or the 
vapour of ether, and a few drops of ammoniacal cuprous chloride 
added, the gas is ignited and the tube rolled about so as to bring 
the products of combustion in contact with the re-agent. The 
characteristic red precipitate of acetylide of copper will be produced 
wherever the flame touches the copper solution. The incomplete 
combustion of coal gas produces a notable amount of acetylene, 
recognizable by its peculiar odour as well as the chemical test. 
Based on the production of acetylene from hydrocarbons, M. 
Berthelot has suggested a new method of detecting them in mixed 
gases.* If, for example, a mixture of carbonic oxide and hydrogen 
or of hydrogen and marsh gas, or any hydrocarbon vapour, be 
submitted to the action of the electric spark for a few minutes, 
acetylene will be produced in the latter mixture, but not in the 
former. 
Lastly, M. Berthelot shows that the compounds which acetylene 
forms with metals offer examples of a new series of compound 
metallic radicals.| He describes at length those containing copper 
and silver, with some of their salts. 
As a point of some technical interest, we may mention that 
M. Perret has discovered a process by which the first step m the 
preparation of citric acid may be taken where the lemons grow, and 
thus save the exportation of the fruit or juice. He first precipitates 
the acid with magnesia, so forming the tribasic citrate; this he 
afterwards boils with another portion of juice, by which he forms a 
bibasic citrate, an easily crystallizable and permanent salt, con- 
venient to transport for the subsequent manufacture of citric acid.t 
In conclusion, we may mention that, after an elaborate investi- 
gation, Fresenius has shown that a mixture of air and carbonic 
acid, or either alone, is only completely deprived of moisture by 
passing over phosphoric anhydride.§ 
PROCEEDINGS OF THE CHEMICAL SOCIETY. 
At the meeting held on December 7, 1865, Dr. Gladstone com- 
municated some Notes on Pyrophosphodiamie Acid, and Dr. Hugo 
Miller described Phenylo-phosphoric Acid and some of its salts. 
The next meeting, December 21, was occupied with a paper by 
Mr. James Yates, “On the best Material for Mural Standards of 
Length.” To extend knowledge of the metric system, it has 
been proposed to the British Association to set up standards on the 
outside walls of public buildings, and My. Yates’s object in intro- 
‘ Bulletin de la Société Chimique,’ Feb., 1866. 
‘Comptes Rendus,’ vol. Ixii., p. 455. 
‘Bulletin de la Societe Chimique,’ Jan., 1866. 
‘Zeitschrift fiir Analyt. Chemie,’ vol. iv., p. 177. 
Gattis * 
