8 Rev. P. Kelland 07J Mossotti's Tlieory of Molecular Action. 



The boiler which I am now using is made of wi'ought iron, 

 and the electricity of the steam discharged from it has been 

 invariably positive, except in the instance I am about to 

 mention. Potash and soda, which in the gun-metal generator 

 tended so strongly to the increase of positive electricity in the 

 steam-cloud, appear to have little influence when introduced 

 into the iron boiler ; but 1 have not yet tried, in the iron boiler, 

 the acids and other things which, in the gun-metal generator, 

 caused the steam to give negative electricity. 



In consequence, however, of the influence which the state 

 of the inner surface of the generator had been proved to ex- 

 ert upon the electricity of the steam, I was induced to try 

 whether the steam from the iron boiler could not be caused 

 to evolve negative, instead of positive electricity, by being 

 brought into contact with a considerable surface of polished 

 brass on its way to the discharging aperture ; and with this 

 view, I conveyed the steam from the boiler through a brass 

 tube, an inch and a half in diameter, made bright and smooth 

 in the inside and terminating in a small hole, at which the 

 steam was discharged. Under these circumstances the elec- 

 tricity of the steam continued to be positive, but was rendered 

 exceedingly feeble. I then moistened the inside of the brass 

 tube with dilute nitric acid, and, by this means, the steam from 

 the iron boiler became for the first time negatively electrified, 

 though not in a high degree. 



Newcastle-upon-Tj ne, Wm. Geo. ARMSTRONG. 



Dec. 9, 1841. 



III. On'M.ossoiii's TJieory of Molecular Action. By the Rev. 

 P. Kelland, M.A., F.R.SS. L.^ E., F.C.P.S., Professor 

 of Mathematics in the University of Edinburgh, late Fellow 

 and Tutor of Queen's College, Cambridge. 



To Richard Taylor, Esq, 

 Dear Sir, 



IT is with great pleasure that I find attention at length di- 

 rected to the interesting subject of molecular equilibrium. 

 Since the appearance of the translation of M. Mos&otti's paper 

 in the Scientific Memoirs*, nothing has been written relative 

 to it, except my own memoir in the seventh volume of the Trans- 

 actions of the Cambridge Philosophical Society. The duty of 

 noticing any objections which are brought against the theory, 

 may, theretoie, seem to devolve on me. It is with this im- 

 pression that I give the following explanation of the points 



• Ta) lors Scientific Memoirs, Vol. i. p. 448. 



