British and Foreign Salt. 177 



(F. a.) If in any mixture of salts, free from the earthy 

 muriates, we are certain that no other sulphates exist be- 

 side those of lime and magnesia, their estimation becomes 

 extremely simple. Decompose two equal quantities of the 

 salt in question, the one by muriate of barytes, the other 

 by oxalate of potash. From the weight of the latter pre- 

 cipitate, we may calculate the quantity of sulphate of lime. 

 Suppose, for example, the oxalate of lime (as was actually 

 the case with the precipitate from 1000 grains of Lyming- 

 ton salt) to weigh twelve grains; these denote 15 of sul- 

 phate of lime, dried at 160° Fahrenheit, which quantity, if 

 decomposed, would give 20^ of sulphate of barytes. The 

 latter number (20-£), subtracted from the weight of sulphate 

 of barytes actually obtained (say 60), gives 3ox grains for 

 the sulphate of barytes resulting from the decomposition 

 of sulphate of magnesia. The quantity of the latter salt, 

 it will be found therefore by applying the rule already given 

 (D. e.), must be 35 grains. 



(F. b.) The same object may be accomplished by decom- 

 posing two equal quantities, the one by oxalate of potash, 

 the other by the compound solution (D. c). From the 

 weights of the precipitates, it is easy to calculate from how 

 much of the calcareous and magnesian sulphates they have 

 resulted. 



(G.) When the salt left by alcohol was known to con- 

 tain muriate of soda and sulphate of magnesia, but no sul- 

 phate of lime, the presence of alkaline sulphates was in- 

 vestigated in the following manner. The salt was dissolved 

 in water, and the solution was divided into two equal por- 

 tions. To the one muriate of barytes was added, and to 

 the other, the compound precipitant of carbonate of am- 

 monia, and phosphate of soda. If the sulphate of barytes, 

 thus produced, bore to the ammoniaco-magnesian phos- 

 phate the proportion of 112 to 90, it was concluded that 

 no other sulphate had been decomposed, but that with base 

 of magnesia. 



(H.) At one time I expected to have ascertained the 

 quantity of sulphate of soda, in an artificial mixture of that 

 salt with sulphate of magnesia and muriate of soda, by the 

 following formula. To d solution of the three salts, heated 

 to a boiling temperature, I added sub-carbonate pf am-r 

 monia, which decomposes the sulphate of magnesia only. 

 I had then a solution containing muriate and sulphate of 

 soda, with sulphate of ammonia; and some carbonate of 

 ammonia. This solution was evaporated to dryness^ and 



Vol. 36. No. 149. Sept. 1810. JVI * the 



