Analyfis of the Schieferfpath from Cornwall. 09! 



from the denciency occaSoned by the incomplete a6lion of 

 the fulphuric acid. 



Still apprehending that refults fo diffimilar might arifs 

 from inaccuracy in the method T had employed, more mi- 

 nute attention vvas paid to the difengagement of the carbonic 

 by the ftronger acids. The following"" experiment was infti- 

 tuted to determine the quantity of muriatic acid carried pver 

 by the effervefcence it excited. This acid was preferred to 

 the nitric for two reafons : being very dilute, and its aAion 

 confequentlv increafcd, the erro^- is (hown in its greatell de- 

 gree; and fmall quantities of it are much more readily de- 

 ledted than of nitric acid. 



Exp. V. 200 grains of fragments of carbonated lime were 

 put into muriatic acid of fpecific gravity 1-17 in the vial al- 

 ready mentioned, having a WouU'e's apparatus fo adapted 

 that 'the carbonic acid difengaged might pafs through water. 

 After the eifcrvefcence had ceafed, the vial containing the 

 muriate of lime was heated in water for nearly an hour, in 

 order to expel the carbonic acid, which, although difengaged 

 from the lime, was held in folution by the water of the dilute 

 muriatic acid. By thefe means the lofs was '6 more than 

 when nitric acid of 1-40 vvas ufcd, occafioned by the more 

 rapid effervefcence. 



To the water through which the carbonic acid had paffed 

 nitrate of filver was added, which occafioned the formation 

 of fuch a quantity of muriate of filver as, from comparing 

 the degree of lurbidncfs, was nearly equalled by -6 of mu- 

 riatic acid. The (light diffimilarity evidently refulted from 

 the evaporation of the water of the muriate of hme by the 

 heat employed to extricate the lafl: portions of carbonic acid. 

 • The ftronger effervefcence which a dilute acid excites, is 

 not the only inconvenience attending it; the \yatcr is capable 

 of combining with a quantity of carbonic acid, which ren- 

 ders it neceflary to emplov heat, as in the above-mentioned 

 experiment, which is totally unncceflary when a concentrate 

 acid is made uie of. 



Analjfis (f the Sch'ufcrfpath . 



Some fragments of fchieferfpath being put into muriatic 

 acid, (Irong effervefcence took place, and nearly the whole 

 was foon diffulved: the folution was colourlefs ; a very mi- 

 nute quantiiv of a finely divided white fubllance remained 

 undillolved.' The folution, divided into parts, exhibited with 

 riaeenis the following appearances: 

 i'rudialc of potadi, a blue precipitate, 

 liiifturc of galls, a dark brown precipitate. 



T ;j Ammonia, 



