260 The Rev. Prof. Callan on a New Single 



From this hydrocarbon, nitro-substitution products may be ob- 

 tained, and I have very little doubt that it is an isomer of cumole. 

 It boils at about 142°. It would seem, therefore, that there are 

 three bodies having the formula C 18 H 12 ; cumole boiling at 

 148°-4, mesitilole boiling at 155°, and the hydrocarbon from 

 eugenic acid boiling at 142°. May not these bodies, and those 

 obtained from toluole, stand in similar relations to one another ? 

 The same differences between their boiling-points are observable. 

 I am still investigating this question with reference to the other 

 members of the benzole scries, and endeavouring by the differ- 

 ences of specific gravity, vapour density, refractive power, &e. 

 of these liquids, to discover their true relations to one another. 



By referring to the table given before, it will be found that, 

 according to my experiments, the increment in the boiling-point 

 in the benzole series for an addition of C 2 H 2 varies between 

 22°-9 and 22°-2. By determining the boiling-points of the con- 

 secutive members of several series, in which not only carbon and 

 hydrogen enter, but also oxygen and nitrogen, we shall be able 

 to learn whether such formula?* as those of Schroder will prove 

 to any extent generally applicable. The substances in such ex- 

 periments must of course be absolutely pure. The present con- 

 tribution, having reference to a simple series containing only 

 carbon and hydrogen, may be considered introductory. Schroder 

 remarks, that between those boiling-points which are theoreti- 

 cally determinable from his formulas and those experimentally 

 observed, a difference of +7 0- 2, + 14 0, 4 may be found. Since 

 the remarks upon the isomers of cumole and toluole were written, 

 I have noticed the close approximation of the differences between 

 the boiling-points of these isomers to this difference of 7°*2. 



February 1855. 



XL. On a New Single Fluid Galvanic Battery, more powerful, 

 and less expensive in construction and use, than any of the Nitric 

 Acid Batteries. By the Rev. N. J. Callan, Professor of 

 Natural Philosophy in the Roman Catholic College, Maynoothf. 



IN a paper published in the Philosophical Magazine for Fe- 

 bruary 1854, I stated that sheet iron coated with an alloy 

 of lead and tin, in which the quantity of lead is five or six times 

 as great as that of tin, and afterwards platinized, might be sub- 

 stituted with advantage for the platinized silver used in Sniee's 

 battery. Being under a necessity of exhibiting occasionally 

 during the academical year, optical experiments which required 

 a very strong light, I was very anxious to have a galvanic bat- 



* Not, however, based on arbitrary numbers. 

 t Communicated by the Author. 



