VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 105 



were in contact, no air or gaz was disengaged from the water by the electrical dis- 

 charges; but on gradually increasing their distance from each other, the position 

 was found in which gaz was disengaged; and which ascended immediately to the 

 top of the tube. By continuing the discharges, gaz was discharged till it reached 

 to nearly the lower extremity of the upper wire, and then a discharge occasioned 

 the whole of the gaz to disappear, a small portion excepted, and its place was con- 

 sequently supplied by water. 



From my own experience I should venture to affirm, that a more particular and 

 more accurate account than that published is requisite, to enable the student, or 

 even the proficient, to institute the above experiment with success. Hence, during 

 the 6 or 7 years which have elapsed since its publication, no confirmation has been 

 published, except the experiment repeated by Mr. Cuthbertson for my satisfaction, 

 as related in my work on the Chemical Nomenclature; though I have heard of 

 many persons, and some of them experienced electricians and chemists, who have 

 made the attempt. But by labouring with Mr. Cuthbertson, since he came to 

 reside in London, I have learned the circumstances on which the success of the 

 experiment depends; and I have received from him effectual aid in continuing a 

 process, with the objects I had in view, the tediousness and even difficulties of 

 which can only be conceived by those who have been engaged in the same pursuit. 

 In the course of my experiments on this subject, Mr. Cuthbertson invented a new 

 method of disengaging gaz from water, by means of the electrical discharges, 

 namely, by means of uninterrupted or complete discharges; whereas the method 

 of Mr. Van Troostwyk was by interrupted discharges. The rationale of the pro- 

 cess according to these two methods, I apprehend, cannot be understood without an 

 explanation; for I find books on electricity do not contain the necessary 

 information. 



In the experiment of Mr. Van Troostwyk, it must be considered, that if instead 

 of water the tubes be filled with air, the whole of the charge of the Leyden jar 

 will pass, at each explosion, from the upper to the under wire, and no interruption 

 in the discharge will happen ; but if they are filled with water, then an interrupted 

 discharge may be caused: by which is meant, that a part of the change only passes 

 at each explosion through the water from wire to wire, and with much diminished 

 velocity. The residuary electricity in the Leyden jar is nearly one half, as may be 

 accurately demonstrated. The reason' of these differences must be assigned from 

 the difference in point of density, elasticity, and conducting power, of the medium 

 of water and of air. It must be added, that though water in large quantity is a 

 good conductor, and air is not, yet water being here in very small quantity it proves 

 a bad conductor; as is the case with the very best conductors. A cubic foot of 

 water is only just capable of receiving, or letting pass through it, a full discharge 

 from a jar of one foot of coated surface; and the quantity of water employed in 

 this experiment not being ^^-^ part of a cubic foot, it is a very imperfect con- 



VOL. XVIII. P 



