1824.] Mineral Waters of Carlsbad. 127 



this quantity is slightly in excess over the former, is more pro- 

 bably caused by the difficulty of conducting the evaporation, 

 io-nition and filtrations in the course of the experiment, without 

 loss, than by the decomposition of any portion of muriate of soda 

 by the acetic acid. These 1*588 gramme represent 0*6495 

 gramme of chloride of sodium. The deficit in the total amount 

 must have consisted of carbonate of soda : the quantity of this 

 salt was, therefore, 0'7845 gramme. 



(B.) The earthy Salts insoluble in Water. — a. These being 

 mixed with nitric acid in a platinum capsule dissolved with 

 effervescence. In order to prevent any loss of the liquid, I am 

 in the custom, when making a solution accompanied with effer- 

 vescence, and also at the commencement of the evaporation, to 

 cover the dish with a watch-glass, the convex side of which is 

 undermost. By this means, the whole of the liquid driven up 

 in consequence of the disengagement of the elastic fluid, is 

 collected upon the watch-glass, and gradually drops down from 

 its central point, while the glass itself is washed by the water 

 which successively condenses upon it during the evaporation. 

 In this experiment the glass happened to have been left on the 

 capsule until the solution had attained a state of dryness. On 

 taking it off, its under side was found to be covered with dull 

 spots, exhibiting distinctly the edges of the drops of water 

 which had condensed upon it during the evaporation. As the 

 same glass had been repeatedly employed for a similar purpose, 

 without sustaining any alteration, it was obvious that, in this 

 instance, fluoric acid had been disengaged, and had corroded it. 



b. The dry mass was moistened with nitric acid, heated, 

 and then dissolved in water. A dark-grey coloured silica 

 remained undissolved, which, after ignition, became white, and 

 weighed 0*044 gramme. 



c. Ammonia produced in the filtered solution an exceedingly 

 slight yellow-coloured precipitate, which, after ignition, weighed 

 0*004 gramme, and presented the appearance of oxide of iron. 

 As fluoric acid, when occurring in the mineral kingdom, is 

 almost always accompanied by phosphoric acid, I examined this 

 oxide of iron before the blowpipe, and obtained from it a fused 

 regulus of phosphuret of iron. We shall, bye and bye, find that 

 this oxide of iron contained also silica, alumina and oxide of 

 manganese. 



d. The liquid which had been treated with ammonia was 

 mixed with oxalate of ammonia so long as any precipitation 

 ensued. The oxalate of lime was calcined, moistened with a 

 solution of carbonate of ammonia, and again heated until it 

 became just visibly red. The carbonate of lime thus formed 

 weighed 0*195 gramme. It was dissolved in nitric acid, the 

 solution was evaporated to dryness, and the residue was dis- 

 solved in alcohol of the specific gravity 0*793. A dark-brown 



