Ohjervai'ions wt Stnntiatt, f 3? 



Experiments to afcertain whether Sirontiatt contains Limf. 



1. TO a folut ion of nitrate of barytes I added fluoric acid, perfedly pure and free from 

 fulphuric acid : the mixture took place without precipitation. 



2. To a folution of nitrate of flrontian I added the fame fluoric acid : the mixture alfo 

 took place without precipitation. 



3. To folutions of the nitrates of barytes and Rrontian put into feparate veflels I added 

 two or three drops of nitrate of lime, and afterwards feme fluoric acid : tliis acid then very 

 foon produced a white precipitate, which was fluate of lime. 



It follows, from thefe comparative experiments, that the nitrate of flrontian did not con- 

 tain lime •, for, if it had contained ever fo little, the fluoric acid would have occafioned a pre- 

 ■cipitation. This acid has fo ftrong an aflRnity with lime that it takes it from the fulphuric 

 acid, when fulphate of lime is holden in folution in water; fo that when a few drops of 

 fluoric^cid are added to a felenitic water, a precipitation takes place as readily as when the 

 oxalic acid is ufed. The fluoric acid prefents therefore an excellent means of deteding the 

 prefence of lime. Very pure fluate of ammoniac may alfo be ufed ; for, if this be mixed 

 with the nitrate, muriate, or fulphate of lime, a decompofition takes place by double aflinity, 

 and the precipitate is fluate of lime. 



Nitrate of StroKtian is nut precipitated, as Nitrate tf Barytes is, iy the Prujfiates of Pot-ajh or 



Lime. 



WE have feen, that the charafters of ftrontian in which it appears moft fimilar to 

 ■barytes, exhibit, neverthelefs, difi"erences fufficiently well marked, when they are fubjefted 

 to a rigorous examination. The following experiment, which is owing to the obfervations 

 of Dr. Hope, prefents a more ftriking diftinftion between the two earths, h was known 

 that nitrate of barytes is totally precipitated by the prufliates of pot-afh and lime. 

 ■Dr. Hope having added prufliate of pot-a(h to a folution of nitrate of ftrontian, perceived 

 only a flight precipitation, occafioned by the iron which accompanies the carbonate of ftron- 

 tian. I had a mind to afcertain this myfelf, and therefore prepared three folutions, viz. 

 I. A folution of native carbonate of barytes in nitric acid : 2. A folution in the fame acid 

 of carbonate of barytes, prepared by the decompofition of barytic fulphate : 3. A folution 

 of carbonate of ftrontian in the fame acid. Thefe three folutions being placed in feparatc 

 V«flels, I added a fufEcient quantity of prufliate of pot-afli, to decompofc them entirely. 

 There was in eflPeft aji abundant precipitate in the nitrates of barytes, and the fupernatant 

 liquors being tried with carbonate of pot-afh gave no Cgn of further precipitation. The 

 nitrate of ftrontian, on the contrary, gave only a weak blue precipitation, in confequencc of 

 die iron which it contained ; and an excefs of prufTiate of pot-afli precipitated nothing more ; 

 but the fupernatant liquor, tried with carbonate of pot-afh, aflbrdcd a very abundant white 

 precipitate, which was carbonate pf ftrontian. 



Thus It appears manifeft, that pruffiate of pot-afh does not at all dccompofe the nitrate 

 of ftrontian, whereas it totally decompofes the nitrate of barytes. This method points out, 

 therefore, a diftinftivc charaOer between the two earths. I fhall not here examine the na- 

 ture of the precipitate which is obtained from the nitrate of barytes when decompofed by 

 prufliate of pot-afti, nor whether the decompofition takes place in confequencc of the forma- 



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