ACCOUNT OF A MINERAL FROM ORKNEY. 89 



100 grains carefully selected from the purest and most solid 

 parts of the specimen were broken into small fragments, and 

 dropt in succession into a flask, containing a cubic inch of 

 muriatic acid diluted with two parts of water, which had been 

 previously poised in a delicate balance. Each fragment was 

 suffered to part with its carbonic acid before another was ad- 

 ded, lest the violence of the effervescence should dissipate 

 any portion of the liquid in the flask. After all effervescence 

 had ceased for some hours, the flask was again accurately 

 weighed ; when it was found to have lost 21.1 grains. As 

 this part of the process requires peculiar attention, the experi- 

 ment was repeated ; and the average of three trials gave 21 

 grains as the quantity of Carbonic Acid in the mineral. 



This result cannot be far from the truth, as it was the same 

 when nitric acid was employed. 



E. 



To ascertain the quantity of strontia and lime, several experi- 

 ments were undertaken. 



1. The muriatic solution D. was evaporated to dryness, in 

 order to expel the excess of acid. The saline mass was dis- 

 solved in water, and slowly evaporated ; the crystals of mu- 

 riate of strontia were successively separated ; but the results of 

 several repetitions of the process not coinciding, a different me- 

 thod was employed to separate the muriates of strontia and 

 lime. 



2. The nitric solution of the mineral was evaporated to 

 dryness, dissolved again in water, and slowly crystallized. 

 The crystals were digested with strong alkohol, by which ni- 

 trate of lime is dissolved, but not nitrate of strontia. The crys- 

 tals were washed by the affusion of alkohol ; and thus the two 

 salts were completely separated. 



vol. ix. p. i. m 3. The 



V 



