Royal Irish Academy. 101 



SOs + CeH^O + CaO + HOj 



and the persulphomesitylate of lime 



2S03 + C6H30 + 2CaO + HO. . 



When an excess of phosphorus is used in the process for making 

 iodide of mesityl, there is obtained in ihe retort a white matter in 

 silky crystals, which dissolves in water, is very acid, and forms well 

 characterized salts, which, when heated, take fire and burn with a well 

 marked flame of phosphorus. This acid is termed hypopfiosp/iomesi- 

 tylous acid 'j and the formula of the hypophosphomesity late of baryta \s 

 P^O + CgH^O + BaO + HO. 



In the decomposition of mesitic alcohol by perchloride of phospho- 

 rus there is obtained an acid which gives a soda salt crystallizing 

 in rhombs which contain water of crystallization. Their formula is 

 P.O. + NaO + CgH.O + SHO. 



Professor Kane stated that he had obtained also the aldehyd of 

 of the mesityl series, as well as bodies procured by the action of chlo- 

 rine and iodine on mesitylene, and the acids which are generated by 

 the oxidation of mesitic alcohol, the history of which bodies shall form 

 the subject of another paper. 



The empyreumatic oil, which is produced in small quantity when 

 mesitic alcohol is prepared by distilling acetate of lime, has been sub- 

 mitted to analysis by Professor Kane, and its composition found to 

 be C,o Hg O. It therefore belongs to the family of which oil of tur- 

 pentine is the base, and is polymeric with camphor, and the pinic, 

 sylvic, and copaivic acids*. 



Dr. Apiohn read a paper " On the Specific Heats of the Aeriform 

 Fluids." ^ 



The first part of this communication was an analysis of, and some 

 critical remarks upon, the labours of those who had preceded the 

 author in the same investigation, particularly those of Dulong. Dr. 

 Apjohn's own method was then detailed. In a paper read by him 



before the Academy in April, 1835, the equationf/"=/— 1?^ + -^ 



was proved to include the solution of the dew-point problem. But 

 the factor a in this expression, which is obviously equal (when the air or 



gas is dry, or in other words, when/"=0) tO'Z-^ x — , is the spe- 



4Sd p 



cific heat under a given volume of the gas which is supposed to be 

 the subject of experiment. Hence if/' and d be determined for the 

 various aeriform fluids by observation, their relative capacities for ca- 

 loric can be compared. Such is the principle of the method. 



Two distinct series of experiments were then detailed, from the 

 second of which, as comprehending those which he conceives to be 

 most accurate, the author has deduced the following table of specific 

 heats : 



* In this abstract the atomic weights are taken, Hydrogen = 1. Oxygen 

 = 8. Carbon = 6- 13. 



t d=t—l' the difference of the temperatures shown by a wet and dry 

 thcrmonioter, and/' is the elastic force of vapour at temperature t'. 



