£74 ANAI/TSIS OF BRITISH AND FOREIGN SALT. 



Method of When the salt was in a state of solution, a measured quan- 



n'uriateof ° tlt ^ was eva P orate0 ' t0 dryness in a sand heat, which was 

 soda, carefully regulated, to avoid the decomposition of the mu- 



riate of magnesia, if any of that salt were present in the so- 

 lution*. 



Each specimen of salt was reduced to a fine powder, and 

 was dried, in the temperature of 180° of Fahrenheit, dur- 

 ing the space of two hours. This was done in order that 

 the different experiments might be made on precisely equal 

 quantities of salt. 



Separation & 



I. To separate the earthy Muriates. 

 (A) On 1000 grains of the dried and pulverized salt, (ex- 

 calcnlation of cept in the case of the foreign salts, when only 500 grains 

 the earthy mu- were used,) four ounce measures of alcohol were poured, of a 

 specific gravity varying from 815 to 820, and at nearly a 

 boiling temperature. To insure the access cf the fluid to 

 every part of the salt, they were greund together for some 

 time in a mortar, and then transferred into a glass matrass, 

 where they were digested for some hours, and frequently 

 agitated. The alcohol was next separated by filtration, and 

 the undissolved part was washed, as it lay on the nitre, with 

 4 ounce measures of fresh alcohol. 



(B.) The united washings were evaporated to drynessf , 

 and to the dry mass a small portion of fresh alcohol was 

 added, to separate the earthy muriates from a little common 

 salt, which had been dissolved along with them. This se- 

 cond solution might, however, still contain a minute por- 

 tion of muriate of soda. It was therefore again evaporated, 

 redissolved in hot water, and mixed with a solution of car- 

 bonate of soda. By boiling for some minutes, the whole of 

 the earths were precipitated, and after being well washed, 

 were redissolved in muriatic acid. This solution, being 



* Muriate of magnesia, according to Dr. M arcet, begins to part with, 

 it* acid at a temperature a few degrees above that of boiling water. 

 This fact explains the observation of Mr. Kirwan, that too great a 

 heat, employed in the desiccation of muriate of magnesia, decreases 

 considerably its solubility in alcohol. (Kirvran on Mineral Waters, 

 p 275-1 



■T In this and all similar cases, the heat was verj cautiously regula- 

 ted towards the close of the process. 



evaporated 



