On graduating Glass Tubes. 99 



with the electrolyte, its increased excitement causes it to at- 

 tract and combine with the acid particle nearest it, a 1 ; when 

 these unite the electricity passes to the first basic particle 

 b 1, giving it an exalted excitement, which causes it to unite 

 with the acid particle a 2, the electric force passing to b 2, 

 which becomes excited in turn and takes the particle a 3; and 

 so on through the chain till the last particle b 5, which, 

 having no further acid to combine with, gives its electricity to 

 the solid conductor which passes along to the battery. If the 

 last particle b 5 be a metal that can exist under the circum- 

 stances in which it is left, such as copper, silver, &c, it ac- 

 cumulates upon that electrode as a deposit; if not such as 

 can exist under these circumstances, such as potassium, &c, 

 it decomposes water and hydrogen is evolved. By this we 

 observe that every equivalent of decomposition will carry an 

 equivalent of acid to the positive electrode. This is exactly 

 what is found by experiment to be the case. That these de- 

 compositions and combinations amongst the particles of a 

 salt may produce a current of that salt in the direction of the 

 electric current producing endosmose, can very easily be con- 

 ceived. 



Whether this be the true philosophy of electrolytic action 

 is yet to be further investigated ; in the mean time it does not 

 appear inconsistent with any experiments I have yet investi- 

 gated : but should it be found not to account for electrolytic 

 action under all circumstances, it will be gratifying should it 

 only prove a stepping-stone to a clearer view of the subtile 

 action of this power. 



It appears to me that the phaenomena observed and de- 

 scribed in these papers favour the idea that electricity is but 

 one power or substance, and that that power is identical with 

 chemical affinity. But the further consideration of this point 

 must be deferred till another opportunity. 



XVIII. On a convenient Instrument for graduating Glass 

 Tubes, invented by Prof. Bunsen of Marburg*. 



rpHIS instrument consists of a mahogany board 5| feet 

 -■- long, 7 inches wide, three-quarters of an inch thick. 

 .Throughout its centre is a groove 1 inch wide, half an inch 

 deep, arched at bottom, for the reception of tubes. At one 

 part, 5 inches from the end, is placed a brass plate, 1^ foot 

 long and 2 inches wide, in such a position that when screwed 

 down its edge comes one-half over the groove. It is furnished 



* Communicated by the Chemical Society ; having been described by 

 Dr. Lyon Playfair January 10, 1846. 



H 2 



