Olfervat'ions on Stronlian. ^21 



not fiiized with any vomiting, and twenty hours afterwards I did not at all perceive that he 

 had felt the fmalleft inconvenience. It will be proper to repeat this experiment with 

 flronger dofes. Blumenbach was alfo convinced that the carbonate of ftrontian, taken in- 

 ternally, did not at all derange the animal oeconomy. Thefe obfervations, therefore, point 

 out a difference between ftrontian and barytes. 



3. The colour of the carbonate of barytes from Anglezark is a grey white : it is fome- 

 tlmes found cryftallized, but more commonly in a ftriated mafs. Its fpecific gravity is from 

 4.2919 to 4.3710. The colour of carbonate of ftrontianis alight green, though it is feme- 

 times found colourlefs and tranfparent : it is ftriated, and fometimes of a regular cryftalline 

 form. Its fpecific gravity is from 3.6583 to 3.6750*. This carbonate is confequently 

 lighter than that of barytes. 



4. Native carbonate of barytes, expofed to a fire which is not too violent, fcarcely lofes 

 any thing of its weight : in a ftronger one it attacks the crucible, and pafles into fufiori. 

 Carbonate of ftrontian alfo retains the carbonic acid pretty ftrongly ; but with caution, and 

 a proper continuance of heat, the carbonic acid may be feparated in the proportion of five 

 or fix hundredths of the fait, without its attacking the crucible : fome care muft, however, 

 be taken not to have the fire too ftrong, as the earth would, in that cafe, attack the cru- 

 cible, and run into a chryfollte-coloured glafs. The carbonic acid therefore is lefs ftrongly 

 retained in carbonate of ftrontian than in that of barytes. 



5. Meflrs. Hope and Klaproth had obferved, that calcined ftrontian was foluble in water, 

 and that, when boiling, it diflblved a fufficient quantity to afford cryftals by cooling ; fo that 

 thefe two chemifts regarded this property in ftrontian as a diftiniSlive charader. M. Klap- 

 roth efpecially never fucceeded in calcining the native carbonic of barytes fufficiently to try- 

 its folublllty in that ftate. When he gave it but a fmall degree of heat. It was not deprived 

 of Its carbonic acid ; and when he applied a greater. It became vitrified. Dr. Hope an- 

 nounced, in a fupplement to his memoir, that he had found means to calcine the native 

 carbonate of barytes in a black-lead crucible, and that he found this earth, thus calcined, 

 was, as well as ftrontian, foluble in boiling water, and fufceptible of cryftallication ; which 

 properties he has accordingly ceafed to confider, fince that time, as charaflers peculiar to 

 ftrontian. I have alfo fucceeded in feparating with facility the carbonic acid from both the 

 native and artificial carbonates of barytes, as well as that of ftrontian, without ufing black-lead 

 crucibles ; and I fliall here defcribe the method which has conftantly proved fuccefsful with 

 me, and the comparative experiments which I have made on this fubjeft. 



Prcce/i /or feparating the Carbonic Acid from the Carbonates of Barytes and Sirontian. 

 I. TO 100 grains of native carbonate of barytes in powder, I added 10 grains of pow- 

 dered charcoal ; and, the whole being well mixed, I made it into a ftiff pafte with boiled 

 ftarch, and rolled it into a ball. Having put into a crucible a little frefli-burnt charcoal 



• In the fpecific gravities in the original, that of diflillcd water is fuppofcd to be 10, the decimal point 

 being put one place more forward than is here done. I have ventured, in conformity to the more ufual, 

 and, as I thiuk, more convenient, mtlhod of puttin;; unity fur this common mcafurc, to point them at 

 above. T. 



Vol. T.—Februart 1798. 3X ia 



