EXPERIMENTS ON SULPHURIC ACID. ]^9 



H.5 as the average, for the quantity of fulphur contained in 

 100 parts of fulphate of barytes, we (hall not be far from the 

 truth. From the accordance of thefe experiments, repeated 

 and varied, I have now no doubt, but concerning the fource 

 where I was to feek the error, which gave 23.43 as the juft 

 proportion. » 



To afcertain this point, I operated in the following manner, *• Investigation. 

 I prepared fome lime, as pure, I believe, as chymical means ha*7 bTLut** f 

 can procure it. I digefled white marble in muriatic acid j and, marble in mun- 

 by leaving an excefs of the earth, was certain, that by the atlc f a i* tbe " 



r i . . . preap. by carb. 



fuperior affinity of lime for that acid, nothing elfe had been cfpotajh, and 

 taken up. Upon trying the folution with ammonia, no preci- w #^ a «^ 

 pitate took place. By means of carbonate of potato, I fepa- 

 rated the lime in the ftate of carbonate ; and, after well wath- 

 ing the precipitate, expofed it in a platina-crucible to a vio- 

 lent heat, till the weight no longer diminifhed. I am ac- 

 quainted with no more efficacious method to prepare lime, fit 

 for the delicate purpofes of fcientific chymiftry. 



One handred parts of this lime were diflblved in dilute mu-II- ioo p. lime 

 riatic acid, in the fame platina-crucible, previoufly weighed : dl ?T ln mur * . 



acid, were preclp, 



and then fulphuric acid was added in fufficient quantity. Sul- by fulpb. acid, * 



phate of lime was precipitated ; and the veflel was expofed to and tlle mar * 



l r a i ii- iii ac,c * and water 



a heat, at nrlt gentle, to evaporate the liquor ; and then, by driven ofF by 



degrees, raifed to a temperature, which could expel every ignition. 

 thing but the combined fulphuric acid, and leave the fulphate 

 of lime completely calcined. The crucible with the fait was 

 then weighed and the augmentation was 76.— It appears to The dry ful- 

 me, that, if we admit (and I fee no reafon that we mould not P hat ? was 7? 

 admit it) that calcined lime and calcined fulphate of lime are wer e diyasfcL 

 wholly exempt from water, it muft be clear, that the 76 addi- 

 tional weight were fulphuric acid ; and, that the fulphuric 

 acid muft in this flate, more than in any other, approach 

 nearer to what may be termed, abfolutely real acid. One 

 hundred parts of calcined fulphate of lime contain therefore 



Lime 57 Component part% 



Sulphuric acid 43 £2?***^ 



100 



By the former experiments (thofe made upon fulphur con- III. ioo parts 

 verted into acid, and then united to barytes) we had the quan- j^' <* 

 .tity of fulphur, contained in fulphate of barytes. By the folvcd in water 



Vol. V.— June. K lattef 



