Intelligence and Miscellaneous Articles. 157 



silicic acid (quartz). The mixture was heated until the whole of 

 the fluorine and the greater part of the sulphuric acid were expelled ; 

 it was then moistened with water, next mixed with four parts of car-l 

 bonate of soda, evaporated, and finally heated to redness for half an 

 hour. The perfectly fused mass was exhausted with water, and after 

 repeatedly evaporating the alkaline solution, each time adding car- 

 bonate of ammonia and redissolving, the phosphoric acid was preci- 

 pitated by chloride of calcium. The exhausted residue, after solu- 

 tion in muriatic acid, yielded, on the addition of ammonia, a preci- 

 pitate of oxide of iron, with a small quantity of alumina and mag- 

 nesia, and some phosphoric acid ; it was therefore again fused with 

 carbonate of soda. The separation of the bases, and also the sepa- 

 ration of the lime and magnesia from the ammoniacal liquid, was ac- 

 complished by the ordinary methods. 



2. The mass treated with sulphuric acid as above was finally re- 

 tained at a temperature below that of redness, until fumes of sul- 

 phuric acid ceased to escape, and was then exhausted with water. 

 According to the statement of Fuchs, sulphate of magnesia (with per- 

 oxide of iron) only should have been thus dissolved ; and by ascertain- 

 ing the amount of sulphuric acid we might expect to obtain the equi- 

 valent amount of fluorine. But this cannot be accomplished, partly 

 because the mineral always contains a little silicic acid which escapes 

 in the form of fluoride of silicium, and partly because the water re- 

 moves phosphate of alumina as well as the sulphate. The portion 

 insoluble in water is likewise decomposed in this case by heating it 

 to redness with carbonate of soda, although by so doing the whole of 

 the phosphoric acid cannot be removed, and the precipitate obtained 

 on the addition of ammonia must be digested and boiled with solu- 

 tion of potash for a considerable time. 



3. The more transparent parts of the mineral, being the most re- 

 cent and the purest, were decomposed by a mixture of an equal weight 

 of hydrate of potash and three times their weight of carbonate of 

 soda. The perfectly fused mass when treated with water yielded an 

 alkaline solution, containing phosphoric acid and fluorine, and an 

 insoluble residue, consisting of magnesia and the other bases, a. The 

 liquid was evaporated to dryness in a water-bath in a platinum cap- 

 sule, treated with water, separated by filtration from a small residue 

 of phosphate of magnesia, hydrochloric acid then added so as to pro- 

 duce a slightly acid reaction, the carbonic acid expelled by a very 

 gentle heat, and then precipitated by ammonia and chloride of cal- 

 cium in a closed vessel. The precipitate, consisting of phosphate of 

 lime and fluoride of calcium, was decomposed by sulphuric acid and 

 alcohol, and thus the lime was estimated ; the alcoholic liquid was 

 slightly evaporated, then mixed with ammonia and chloride of cal- 

 cium, and the quantity of phosphoric acid in the phosphate of lime 

 ascertained by decomposing it with sulphuric acid. b. The residue 

 of the exhaustion of the fused mass, when acted upon by hydrochloric 

 acid, left a residue consisting of silicic acid. The precipitate thrown 

 down from this solution by ammonia also contained some phosphoric 

 acid, it was therefore again heated with carbonate of soda. It con!*' 



