Nickles on Fluor if t 



397 



Witli 



litres only to find fluorine. Thus the mineral water of Plom- 

 bi^res contains more than that of Vichj, and less than that of 

 Selters or Antogast. It has been detected with four litres of 

 the water of Plombieres, eight of that of Vichy ; while it is not 

 distinguishable in eight litres of that of Niederbrunn, nor in 

 sixteen of the water of Soultzmatt; and again it maj be de- 

 tected in one litre of the water of Chatenois. Thus while fluo- 

 nne is generally present in mineral waters, the proportions varj 

 largely. Besides, we. may conclude that mineral waters rich in 

 cKlorids are not, as lias been believed, a result of the infiltration 

 of the waters of tlie sea. 



Art. XXXI. — On Fluoriferous Sulphuric Acid and its purification ; 



by Jerome Nickles. 



I 



It is now forty years since chemists were surprised by an an- 

 nouncement by Mullen, that when peroxyd of manganese or 

 minium, free from chlorine, is treated with dilute sulphuric acid, 

 a certain quantity of chlorine is evolved. It is useless to recall 

 the hypotheses provoked by this curious reaction, appearing at 

 a time when the nature of chlorine was little understood. At 

 present, the mystery lias passed away, and it is well known, that 

 the chlorine was derived from a small quantity of hydrochloric 

 acid existing as an impurity in the sulphuric acid of commerce. 



But the liict respecting chlorohydric acid is now found to be 

 true also of fluohydric acid ; and it is evident from the preceding 

 paper that already much confusion and error have arisen from 

 this impurity in sulphuric acid derived from the nitrate of soda 



employed in its manufacture. 



The practicability of purifying this acid I have proved on 

 samples taken from various sources. 



In my first trial I endeavored, in view of the volatility of this 

 %dracid and its aflSinitv for water, to drive it ofi" by the heat of 

 ebullition after diluting the acid with as much water. But it 

 was a failure ; the hydrofluoric acid was retained in consequence 

 of the well known powerful action of mass, a large quantity of 

 one substance (the sulphuric acid) controlling the other which 

 ^&& in so small proportions. 



After various attempts, among which gelatinous silica was 

 tried, I came to the following very simple process. In a porce- 

 lain capsule, or better still, in the bulb of a retort, the neck ot 

 which has been removed, a certain quantity of the acid to be 

 purified was introduced, and diluted with twice its volume of 

 Stilled water • it was then placed in a sand-bath and heated 



