l^ew analytical Researches, &c. 405 



tjave, they will propel the bar forwards proportioned to 

 their weight and the space through which they move, so 

 that there is only the friction of the blocks to overcome. 

 Supposing the pressure upon the piston to be SOOib., the 

 weight of all the blocks w^ll be about 500lb for such a 

 sized piston, and will seldom exceed more for the largest 

 engines, as the space fur the bar to pass will be nearly the 

 same in ail, the strength of the bar depending upon its 

 breadth, not on its thickness : thus 800lb. will move 

 through the space of ]6 feet, whilst 50o!b. goes through 

 the space of half an inch: then, if the descending of the 

 blocks is taken into consideration as before described, the 

 friction of the blocks will oiake no sensible difference to the 

 progress of the piston. 



" The lid M being the only opening into the engine and 

 the only stuffing box, and that covered with water, no air 

 can «ntcr but what is contained in the water used for in- 

 jection. 



"■ A very small fly is requisite, as the momentum is al- 

 ways in one direction, and t).ut may be at any convenient 

 distance, as circumstances may require." 



LX. New anahjtical Researches on ike Nature of certain 

 Bodies, being an Appendix to the Bakerian Lectnre for 

 ]80S. By Humphry Davy, Esq. Sec. R.S., Prof. 

 Chem, R. I. 



[Concluded from p. 347.] 



II. Further Inquiries respecting Sulphur and Phosphorus. 



J. HAVE stated, in the last Bakerian Lecture, that hydrogen 

 is produced from sulphur and phosphorus in such quanti- 

 ties, by Voltaic electricity, that it cannot well be considered 

 as an accidental ingredient in these bodies. I have likewise 

 stated, that wlien potassium is made to act upon them, the 

 sulphurets and phosphurcts evolve less hydrogen in the 

 form of compound inflammable gas by the action of an acid, 

 than the same quantity of potassium in an uncombined 

 state, and from thi.-> circumstance 1 have ventured to infer, 

 that they may contain oxygen. 



On the idea that sulphur and phosphorus are deprived of 

 some of their oxygen by potassium, it would follow, that 

 when the compounds formed in this experiment are de- 

 composed, these substances ought to be found in a new 

 state; deoxygenalcd, as far as is compatiblt with their ex- 

 istence in contact with water. 



C c 3 With 



