106 Mr. Joule on the Intermittent Character of the Voltaic 



of one or two matters, the quantities of which were too small 



to admit of determining their precise nature. 



The residual matter which had been treated with so many 



solvents was regarded as lignin or woody matter. No starch 



was found in any stage of the analysis. 



The amount of water was ascertained by a heat of 240° and 



the ashes by incineration. 



The result of the analysis was as follows : — 



Gum 6-73 



Legumin or vegetable casein . 3*8 

 Vegetable albumen .... 0*42 



Fixed oil 0*73 



Ashes 0*61 



Water 9*37 



Lignin or woody matter . . . 8T34 



Too 7- 



In the ashes were found phosphate of lime, sulphate of 

 potash, chloride of potassium, carbonate of lime, and a little 

 siliceous matter. A little iron present probably proceeded 

 from the tools of the turner. 



XX. On the Intermittent Character of the Voltaic Current 

 in certain cases of Electrolysis ; and on the Intensities of 

 various Voltaic Arrangements. By J. P. Joule, Esq.* 



1 T can hardly have escaped the notice of electricians that, 

 ■*- in some instances of electro-chemical decomposition, the 

 needle of a galvanometer included in the circuit will indicate 

 by its unsteadiness a very irregular flow of electricity. I have 

 not, however, been able to meet with any description of the 

 phaenomena, which are generally so trifling in the extent of 

 their manifestation as to induce the belief that they arise from 

 accidental and unimportant causes. It is now more than a 

 year since I observed some very striking examples of the phae- 

 nomena in the course of some experiments on the calorific 

 effects of electrolysis, but I was too much interested in the 

 subject immediately in hand to allow them to occupy much 

 of my attention. They have since, however, appeared to me 

 to have an important bearing upon the theory of electrolysis, 

 and on this account to deserve the attention of philosophers. 

 I propose to begin by mentioning the old experiments just 

 referred to, and then to relate the progress I have recently 

 made in the investigation. 



The following experiment was made on the 9th of July, 



* Read before the Literary and Philosophical Society of Manchester, 

 December 26, 1843; and now communicated by the Author. 



