202 Dr. Hare on Prof. DanielFs Defence 



to bring my apparatus to its present degree of efficiency. My 

 opinions upon these points will be found recorded in two 

 papers which appeared in the Philosophical Magazine, one 

 in January 1842, [S. 3. vol. xx. p. 5.] and the other in the same 

 month of the present year; but in both these papers I expressed 

 a doubt as to friction being the exclusive cause of the excitation. 

 Some of the difficulties which I then felt in ascribing the effect 

 to friction have been cleared away by your masterly investigation 

 of the subject; but others I am bound to say still remain un- 

 shaken. In operating with a small boiler made of bronze or 

 gun-metal, I have seen the apparatus pass from one electrical 

 state to the other, under circumstances which appeared to 

 preclude the possibility of any change having taken place in 

 the condition either of the steam or the watery particles ejected 

 with it. I have also tried numerous variations of the dischar- 

 ging orifice, which proved much less effective than a simple cy- 

 lindrical passage, although apparently calculated to produce a 

 far greater degree of friction. Still however I believe that 

 the effects are essentially owing to friction, either of the steam 

 and water combined, or of the water alone; and I think it 

 probable that all the phaenomena which have been observed 

 will ultimately be reconciled with the theory which you have 

 so boldly and explicitly announced. 



I remain, dear Sir, yours very truly, 

 Newcastle-upon-Tyne, August 12, 1843. W. G. ARMSTRONG. 



XXVI. Letter from Dr. Hare on Professor DanielFs Defence 

 of the view taken by the latter of certain Electrolytic experi- 

 ments, which have been represented as proving the existence 

 of a compound radical {oxysulphion) in certain sidphates. 



To R. Phillips, Esq. 

 Dear Sir, Philadelphia, June 30, 1843. 



1. HAVE read in the Philosophical Magazine for June, 

 [S. 3. vol.xxii. p. 461.] a friendly letter to you from Pro- 

 fessor Daniell, in reply to some strictures made by me upon 

 one of the arguments advanced in proof of the existence of 

 compound radicals in certain salts. Hoping that you will ho- 

 nour the remarks which I am about to make with a place in 

 the same work, and presuming that no reader will favour them 

 with a perusal who has not read or cannot refer to the letter in 

 question, I will proceed as if that letter were before us. 



2. I had advanced, that when aqueous solutions of oxysalts, 

 of which the base is a metallic oxide, the sulphates of soda, 



