SfK WILLIAM .S//..J//..V.S, 1-.R.S. 297 



In the discussion of the Paper 



" ON THE RESULTS OF THE USE OF CLAY RETORTS 

 FOR GAS MAKING,"* by Mr. J. CHUIMI. 



MR. C. TV. SIEMENS said, that although he would not attempt 

 to point out the rationale of the fact, that the leakage increased in 

 the direct proportion of the pressure, yet he thought the experi- 

 ments of Professor Graham, upon the transpiration of gases, bore 

 somewhat upon this interesting question. Those experiments 

 went to show, that when gases issued through narrow tubes they 

 did not transpire, or issue in proportion to the law of gravitation, 

 but according to some totally different law, which had not as yet 

 been clearly laid down. If an explanation might be attempted, 

 he should say, that the gas, in issuing through very small capillary 

 spaces, was so much checked in its progress, that its inertia was 

 destroyed at every step, and it was only the excessive friction 

 which retarded it virtually. But if it was merely the friction that 

 it had to overcome, it would be evident that the leakage would be 

 in proportion to the pressure applied. This argument would 

 apply in a greater degree with regard to gas than atmospheric air, 

 because the specific gravity of coal-gas was only ()'5 at its ordinary 

 temperature ; but when it was heated to 800 in the gas retort it 

 would not weigh half as much. The inertia of the gas was, there- 

 fore, exceedingly small ; but being in a highly elastic state, the 

 friction was, on the contrary, considerable. Observations had 

 been made on the greater quantity of gas produced from clay 

 retorts than from iron retorts. Although he had no practical 

 experience in this matter, he would suggest, whether in those 

 cases where the greater quantity of gas was obtained, the exhauster 

 had not been worked to a great extent ; so that the leakage 

 through the walls of the retort was from the exterior to the 

 interior or into the retort. 



* Excerpt Minutes of Proceedings of Hie Institution of Civil Engineers, Vol. 

 XVI. Session 1856-7, p. 320. 



