TRANSACTIONS OF SECIION B. 681 



oiis under the most favourable conditions, and there is a loss of 20 per cent, or one- 

 tifth of the light power. 



The practical working of mineral oil apparatus on the large scale has resulted in 

 the obtainment of permanent gas with an illuminating power of 75 per cent, of the 

 total light of the oil as oil. The best working apparatus I have met with is 

 Pintsch's, where such results can be obtained day by day. 



The permanent character of the gas obtained from mineral oils has been proved by 

 the testing of the gas after storage in gas-holders in the ordinary way ; and even 

 under the exceptionally severe test of submitting the gas to the pressure of 10 

 atmospheres, as in Pintsch's storage cylinders, the loss in candle power after a 

 month's compression was not more than three candles or about 5 per cent, of the 

 light. 



The oil gas has now been successfully employed in the lighting of dwelling- 

 houses and railway carriages, for lighthouse service iu the illumination of buoys, 

 and in the working of gas engines for sounding fog-horns, as at Langness in 

 the Isle of Man ; and at the present time large apparatus are being fitted up on 

 Ailsa Craig in the Firth of Clyde for the production of the oil gas to be used alike 

 for the illumination of the lighthouse lanterns and for the working of the gas 

 engines connected with the fo"--horns. 



9. Oh the Diamondiferous Deposits of South Africa and the Ash of the 

 Diamond} By Professor Sir H. *B. Roscoe, Ph.D., LL.D., F.E.S. 



10. On aBedetermination of the Atomic Weight of Cerium. By H. Robixson. 



TUESDAY, SEPTEMBER 2. 



The following Papers were read : — 



1. Chemical Changes in their relations to Micro-organisms. By Professor 

 E. Feakkland, D.C.L., M.D., F.B.S. 



The author explained the two kinds of chemical action — \iz., that in which 

 substances brought into contact mutually undergo chemical change ; and, secondly, 

 that in which chemical change is effected in one substance by contact with another, 

 which itself suffers apparently no alteration. To the latter are usually assigned the 

 chemical changes forming the subject of this paper. 



The discussion was confined to the study of organisms belonging to the animal 

 kingdom, and, in order to narrow the discussion, the author proposed the fol- 

 lowing definitions : — ■ 



1. A plant is an organism performing synthetical functions, or one in which 

 these functions are greatly predominant. 



2. An animal is an organism performing analytical functions, or one in which 

 these functions greatly predominate. 



From a physical point of view these definitions may be thus formulated : — 



1. A plant is an organism which transforms actual into potential energy. 



2. An animal is one which changes potential into actual energy. 



All micro-organisms appear to belong to the second class. In that portion of 

 the animal world with which we are best acquainted oxidation is the essential con- 

 dition of life ; it is the kind of action by which the animal changes potential into 

 actual energy, and this actual energy "is manifested in the phenomena which we 

 term life. There are, however, many other chemical transformations in which 

 potential becomes actual energy, and which, therefore, can support life. Besides 

 such changes as are known to be thus utilised by micro-organisms there are many 



1 Printed in full in Proc. Lit. an-l Phi!. Soc. Manchester, vol. xxiii. pp. 5-10, 1884. 



