246 Sir B. C. Brodie on the Synthesis of Marsh-gas, fyc. [Apr. 3, 



the gas, together with a trace of oxygen, which haye been omitted from 

 the calculation. 



The result of this reaction is expressed in the following equation : — 

 CO + 3H 2 =CH 4 +H 2 0. 



This fundamental experiment, which constitutes the basis of a new 

 method of chemical synthesis, susceptible of the most varied applica- 

 tions, and of peculiar interest in reference to the explication of natural 

 phenomena, was commenced by me on the 10th of January last at Oxford, 

 in the laboratory of my friend and successor in the Chair of Chemistry, 

 Professor Odling ; and two analyses of the gas were completed, and the 

 results attained in the course of a week from that date. 



In a similar experiment made with a mixture of hydrogen and carbonic- 

 acid gas, a contraction also occurred, attended with the formation of 

 water. The gas which resulted from the experiment was found to con- 

 sist (after the absorption of carbonic acid) of hydrogen and carbonic oxide, 

 together with a little marsh-gas. Traces of oxygen and nitrogen were 

 also present. Minute drops, too, of an oily liquid appeared in the tube. 

 This liquid, after the conclusion of the experiment, was dissolved in a 

 small quantity of water. The solution was strongly acid and had a 

 pungent taste. It reduced an alkaline solution of terchloride of gold and 

 an ammoniacal solution of nitrate of silver. These reactions are the 

 characteristic properties of formic acid, of which we may infer the syn- 

 thesis to have been effected according to the equation 



H 2 + C0 2 =H 2 C0 2 . 



I may avail myself of the present opportunity to place on record the 

 following important facts in reference to the action of electricity on car- 

 bonic-oxide gas. 



"When pure and dry carbonic oxide is circulated through the induction- 

 tube, and there submitted to the action of electricity, a decomposition of 

 the gas occurs, attended with a gradual and regular contraction, which, in 

 the form assumed in my experiments, occurred at the regular rate of 

 about 5 cub. centims. in an hour. Carbonic acid is formed, and simul- 

 taneously with its formation a solid deposit may be observed in the 

 induction-tube. This deposit appears as a transparent film of a red- 

 brown colour, lining the walls of the tube. It is perfectly soluble in 

 water, which is strongly coloured by it. The solution has an intensely 

 acid reaction. 



The solid deposit in the tube, in the dry condition before it has been 

 in contact with water, is an oxide of carbon. Samples, however, made in 

 different experiments do not present precisely the same composition ; but 

 nevertheless they appear to belong to a certain limited number of forms 

 which repeatedly occur, and may invariably be referred to the same general 

 order or system. This system is, or appears to be, what I may term an 



