1874.] On the Synthesis of Formic Aldehyde. 171 



tained indicated that the explosion was transmitted from charge to charge 

 at the rate of between 450 and 640 metres (1500 and 1800 feet) per 

 second. These experiments with tubes showed that, when the relations 

 between the amount of explosive material, the diameter of the tube, and 

 the space intervening between the charges are such as to ensure the 

 transmission of detonation, its rate is about one third of that at which it 

 travels along a continuous mass, or continuous row of distinct masses, of 

 the same material. 



The concluding part of this memoir deals with a subject only inci- 

 dentally referred to in the former memoir on explosive agents, and which 

 has since that time acquired considerable importance namely, the 

 manner in which the accumulation of heat in a mass of explosive ma- 

 terial, and other conditions, may operate in bringing about or promoting 

 violent explosion or detonation. 



February 12, 1874. 

 JOSEPH D ALTON HOOKER, C.B., President, in the Chair. 



The Presents received were laid on the table, and thanks ordered for 

 them. 

 The following communications were read : 



I. " Note on the Synthesis of Formic Aldehyde." By Sir B. C. 



BRODIE, Bart., F.R.S. Received February 5, 1874, 

 In a former note I communicated to the Society the result of an 

 experiment in which a mixture of equal (or nearly equal) volumes of 

 hydrogen and carbonic oxide had been submitted, in the induction-tube, 

 to the electric action. My expectation in making the experiment had 

 been that the synthesis of formic aldehyde would be thus effected accord- 

 ing to the equation CO+H 2 = COH 2 . The only permanent gas, however, 

 other than the gases originally present in the induction-tube, which 

 appeared in the result of the experiment was marsh-gas. When a mix- 

 ture of hydrogen and carbonic acid gas was similarly operated upon, the 

 same hydrocarbon, together with carbonic oxide, was formed. I have 

 now, however, succeeded, by a modification in the conditions of the latter 

 experiment, in attaining the object which I originally had in view. 

 Evidence of this is afforded by the following analysis : The gas analyzed 

 was the result of submitting to the electric action about equal volumes of 

 hydrogen and carbonic acid. After removal from the gas of carbonic acid 

 and carbonic oxide, and also of a trace of oxygen, 191-2 volumes of gas 

 remained, in which were found, at the conclusion of the analysis, 2- Q 

 volumes of nitrogen. Deducting this amount of nitrogen, 188-6 volumes 

 of gas remain, containing the residual hydrogen in the gas, together with 



o 2 



