432 M. Stromeyer on Polyhalite. [Dec* 



2. Similar effects are produced by caustic ammonia, yet the 

 ammonia does not render the solution in the least turbid if it be 

 previously acidulated by nitric acid. 



3. Subcarbonate of potash produces a copious white precipi- 

 tate, which afterwards subsides in the form of a white powder. 



4. Similar effects attend subcarbonate of ammonia. 



5. Mineral acids, when infused into this solution, produce no 

 change. 



6. Of the vegetable acids oxalic acid instantly causes a very 

 copious precipitate. Tartaiic acid likewise, if poured on in con- 

 siderable quantity, renders the solution turbid, and produces a 

 white crystalline powder, which on examination is found to 

 possess all the properties of cream of tartar. 



7. Oxalate of potash, when added, immediately forms a very 

 plentiful precipitation of oxalate of lime ; after the separation of 

 which both pure and subcarbonate of potash, as well as caustic 

 ammonia mixed with the remaining solution, produce a white 

 precipitate. But carbonate of ammonia and neutral carbonate of 

 potash produce no further turbidity. 



8. It is instantly rendered turbid by muriate of platinum, and 

 there is afterwards frequently deposited a yellowish sandy pow- 

 der, which on examination is found to consist of muriate of 

 platinum and potash. 



9. If muriate of barytes be poured upon the solution, it imme- 

 diately produces a copious separation of a white sediment inca- 

 pable of being dissolved either by water or by acids. 



10. Acetate of lead immediately causes a white precipitate 

 not soluble in acetic acid. 



1 1 . Nitrate of silver produces only a shght milky appearance, 

 and a little muriate of silver is deposited. 



12. An infusion of galls neither changes the colour of the 

 solution, nor occasions any other visible change. 



13. Prussiate of potash and iron is attended with similar 

 effects. 



14. On adding hydrosulphuretted potash, the solution is not 

 disturbed. 



It is very evident from the preceding experiments that this solu- 

 tion of polyhalite, contains sulphate of lime, sulphate of magnesia, 

 and also sulphate of potash, with a small portion of muriate of 

 soda. 



But in order to ascertain whether the fossil contained any 

 sulphate of soda, I precipitated a portion of the solution by the 

 acetate of barytes, and separating the sulphate of barytes, I 

 evaporated it until completely dry. After which, I heated the 

 mass thus dried, and the acetic acid being entirely expelled and 

 decomposed, I extracted from the remaining powder, by means 

 of boihng water, whatever was soluble ; but this alkaline solu- 

 tion, when concentrated by heat, and rendered turbid by means of 

 muriate of platinum, betrayed only some tra,ces of muriate of soda, 



