Dr. A. W. Hofman on Bases in Coal-gas Naptha. 115 

 Table. (Continued.) 



4.-.. 

 4(>\ 



47. 

 48. 



4'). 



5ft. 



Negative elements. 



Copper Sulphate of copper 



do. do. 



f Platinized \ J Dilute sul- \ 

 X silver J \ phuricacidj 

 do- do. 



do. 

 do. 



do. 



do. 



Positive elements. 



Inten 

 aity. 



| Dilute sul- "I 

 \ phuric acid J 

 do. 



do. 



do. 

 J Solution of 

 X common salt 



Iron 

 Copper 

 Amalg (1 zinc 

 Iron 



Amalg' 1 zinc 

 Solution of potassa Amalg d zinc 



} 



49 

 4 

 65 

 17 

 68 



The use of the peroxides of lead and manganese, as negative 

 elements of the voltaic pile, has been recently pointed out by 

 De la Rive*. By using the peroxide of lead with either dilute 

 sulphuric acid or a saline solution, he has produced a battery 

 of greater intensity than the pile of Grove f- It will be seen, 

 on reference to the table, that an arrangement consisting of 

 peroxide of lead moistened with sulphuric acid in contact with 

 platinum, and solution of potassa in contact with amalgamated 

 zinc, is half as intense again as the ordinary cell of Grove. 



I may observe that a single cell of any of the arrangements 

 given in the table, the intensity of which is above 200, is able 

 to decompose water into its gaseous elements with facility. 



I think we can deduce from the table a general law, which 

 may be stated thus: — "The difference between the intensities 

 of any two electro-positive metals immersed in similar solu- 

 tions is a constant quantity, whatever variations may be made 

 in the negative elements of the cells." Thus the difference 

 between the intensities of No. 47 and No. 48 is 48, while the 

 difference between the intensities of No. 20 and No. 21 is 47, 

 and between No. 44 and No. 45 is 51. Thus again the dif- 

 ference between No. 10 and No. 12 is 82, while that between 

 No. 38 and No. 40 is 78, or only one-twentieth less. 



XXI. A Chemical Investigation of the Organic Bases contained 

 in Coal-Gas Naphtha. By Dr. Augustus William 

 Hofman, Assistant in the Giessen Laboratory %. 



Preliminary Remarks. 

 f\F the numerous oleaginous fluids formed from the decom- 

 ^-^ position of organic bodies by heat, those of wood and 

 of mineral coal have been, up to the present time, the most 

 carefully examined. The knowledge obtained from these 



* Archives de t Electricite , No. 8, p. 166. 



[t The use of peroxide of lead as the negative element was originally 

 proposed by Prof. Grove himself in Phil. Mag. S. 3. vol. xv.p. 290. — Edit.] 

 % Communicated by the Author. 



I 2 



