On an Improved Form of Coal- Calorimeter •. 451 



saying that the primitive atmosphere was most probably a 

 very extensive one, perhaps a hundred or several hundred 

 times greater in extent than our present atmosphere. It 

 may have consisted principally o£ carbonic acid, or it may 

 have contained, either in addition to or instead of carbonic 

 acid, large quantities of hydrogen, hydrocarbon gases, and 

 carbonic oxide. At present our information regarding the 

 data bearing on this question is not definite enough to decide 

 the point with certainty, but we may reasonably hope that 

 sufficient evidence will sooner or later accumulate to give a 

 fairly decisive verdict. 



L. On an Improved Form of Coal-Calorimeter. By Walter 

 RoSENHAm, B.A. {Cantab.), B.C.E. {Melbourne)*. 



THE author recently designed a coal-calorimeter for use 

 in a Works laboratory i« In doing so, he was guided 

 in the first instance by an instrument which was shown to 

 him by the courtesy of Professor T. Hudson Beare { at the 

 Engineering Laboratory of University College, London, and 

 the author wishes to acknowledge his indebtedness to Pro- 

 fessor Hudson Beare in this matter. The instrument which 

 the author saw at University College had the advantage of 

 great simplicity, but on trial under the somewhat different 

 conditions of a Works laboratory certain improvements 

 suggested themselves, and, after a number of intermediate 

 forms, the present instrument was arrived at. The author 

 was greatly aided in this work by the Cambridge Scientific 

 Instrument Co. 



In the present form of coal-calorimeter the Thomson 

 principle i< retained §, and the coal is burnt in a stream 

 of oxygen while inclosed in a chamber immersed in the 

 water of the calorimeter. The calorimeter therefore consists 

 of two essential parts, a vessel for containing the water, and 

 a chamber in which the combustion takes place. The 

 former is a rectangular vessel of sheet-brass, containing 

 about "1\ litres of water, while the latter is much smaller, 

 and is made principally of glass and provided with a set 

 of pipes and valves for the admission of the oxygen and 

 the escape of the products of combustion. A< the improve- 



* Communicated by Professor Ewing, F.R.S. 



t Of Messrs. Chance Bros. & Co., Ltd., Glass Works, near Birmingham. 

 X Prof. Hudson Beare states that this instrument was designed by- 

 Mr. Legros, A M.Inst.C.E. 



§ Win. Thomson, F.R.S., Journal Soc. Chem. Ind., 20th Xov. 1896. 



