Application of Hydraulic Power to Mercurial Pumps. 313 



Another formula seems also probable, and indicates better 

 what may be called the line of least resistance in the molecule 

 in the quadrivalid or tetravalent oxygen 



0=As>° 3 "°\As=0- 



The Professor also states quite clearly his opinion that valency 

 is a whole number; and it is pleasing to quote that, in point- 

 ing out that chemists were investigating relations of consti- 

 tution and atomic linking formerly regarded as subjects which 

 could never be properly investigated, he adds: — "At the 

 present time we consider this research difficult, but we have 

 numerous proofs in the results which we have already gained 

 that it is not only capable of solution, but that it also affords 

 a very fruitful field for the spirit of investigation." It is to 

 hoped that some of the remarkable compounds discussed in 

 these papers will be carefully and minutely examined — J. F. H. 



XL. The Application of Hydraulic Power to Mercurial 

 Pumps. By Fkederick J. Smith, M.A., Millard Lecturer, 



Trinity College, Oxford*. 



IN the mercurial pump of the Topler type, a cistern of 

 mercury has to be lifted periodically through about four 

 feet. In a form of mercurial pump of this family, devised by 

 the author of the paper, the receiver of the pump has been 

 made very large in comparison with the vessel to be exhausted, 

 in order that the time of exhausting may be diminished as 

 much as possible. The large size of the receiver, holding, as 

 it does, nearly 40 lb. of mercury, increased the utility of the 

 pump greatly, while it added much to the labour of working it. 

 In order to reduce all manual labour to a minimum, the pump 

 has been made self-acting by the addition of an hydraulic 

 motor, having a 4-foot stroke, controlled by a side-valve similar 

 to the D-valve of a steam-engine : this valve is actuated by an 

 auxiliary motor and valve, acted on by a projection from the 

 end of the main piston. The figure shows the disposition of 

 the pump and motor : the motion is quite smooth, and suitable 

 for the work to be done, the motion at the end of the stroke 

 being automatically checked. The cylinder is made of thick- 

 drawn brass tube, the flange being brazed on. 



Description of figure : — A is the cylinder, H the valves, 

 K the inlet of the water. The cistern of mercury is attached 



* Communicated by the Author ; being abstract of a paper read before 

 the Ashmolean Society, Oxford. 



