Defcftption of an Improvement in the Steam Engine, j4y 



It Is remarkable that platina, though It refifts the afllon of common fire, is more eafily 

 fufed by electric difsharges than copper, filver, or gold, and feems to be as greedy of 

 oxigen as any of the other metals. But thefe experiments have not been fufficiently ex- 

 tended to fettle the laft mentioned property. 



It is well known that all metals which are fublimable by common fire, abforb oxigen in 

 different degrees, and likewife in different proportions, according to the different degrees 

 of heat employed ; this feems likewife to take place when they are fublimed by eledlric 

 difcharges, but the proper degree of difcharge for each metal remains for inveftigation ; 

 and as different metals differ as conductors of the ele£lric fluid, (which has never yet been 

 well defined) this furnifl^es matter fufficient for a future purfuit. 



The lateft experiments upon the conducing power of metals were made by Dr. Van 

 Marum and myfelf, at Haerlem, but as I had not at that time invented the eleftrometer 

 which I have at prefent, and which the nature of the experiment required, I have fomc 

 reafon to think that they are not pcrfeflly accurate. I have concluded thefe experiments, 

 without proceeding to the nonduftile metals, becaufe I know no way of arranging the 

 others, fo that they can be a£led upon with fufficient accuracy. 



The experiments which have been made upon the different metals mentioned, have bee» 

 very numerous, excepting zinc, but for the fake of brevity, and to avoid tautology, I have 

 only mentioned thofe which I thought to be abfoluttly neceflary. 



V. 



Defcription of an Improvement in the Steam Engine, by means of ivhich the Boiler is con- 

 Jlantlyfupplied ivith Water already heated nearly to the point of Ebullition. , Communicated 

 by Mr. Peter Keir, Engineer.* 



T. 



HE fleam engine, of which we have fo many accounts In Introdudiory and other 

 works, and which for its fcientific contrivance and extenfive utility cannot be too highly 

 regarded, may be traced in its hiflory through a few great and (trlking degrees of improve- 

 iDCnt, the intention of every one of which confifls in producing the greatefl quantity of 

 moving force with the leaft pcffible confumption of fuel. It Is probable that the original 

 engine of the Marquis of Worcefter may have been a mere veffel into which water flowed 

 by its weight, and was thence driven upwards by fleam : Capt. Savary feems to have been 

 the flrfl who ufed the vacuum formed by fleam ; into which the water was urged by th? 

 atmofphere : Papin in a crude way, and Newcomen and Cawley in a more perfedl method, 

 ufed a folid piflon : and laflly, James Watt greatly improved the engine of the latter ope- 



• In converfation. I am very forry that the latenefs of the date of this flieet at prefs, does not allow me 

 time to fend and inquire the name of the inventor, which I omitted to write down. The improvement is 

 uader patent, which, with the name, I (lialJ mention in my next. 



, U 2 rators 



