Prof. Berzelius on the Orange Gas Produced, fyc. 129 



earthy phosphates remain on the charcoal while the soda pe- 

 . netrates it, and do not give a limpid mixture when they are 

 melted on a leaf of platina. With twice its weight of carbo- 

 nate of lime, it fuses at a red heat, without, however, attacking 

 the platina, as lithia ordinarily does ; but if some drops of 

 water are added to it, and afterwards evaporated, the platina 

 becomes yellow all round when the mass is heated anew. 



2. Professor Berzelius *s Experiments on the Orange Gas pro- 

 duced from a mixture of Fluor-Spar and Chromate qf Lead. 



As the English and French Journals have already given 

 an account of Professor Berzelius 1 s experiments on'the differ- 

 ent combinations of the fluoric acid which have facilitated the 

 reduction of Silicium, Zirconium, and Tantalum, we shall not 

 at present enter upon the subject. 



A German chemist, M. Unverdorben, has published some 

 experiments on the fluoric acid, the most curious of which 

 was that in which, after mixing together fluor-spar and 

 chromate of lead, he distilled them in a leaden retort, with 

 fuming or anhydrous sulphuric acid. From this there result- 

 ed a gas, which could not be collected, because it destroyed 

 the glass. This gas gave a very thick yellow or red smoke. 

 It was readily absorbed in water, which was then found to 

 contain a mixture of chromic and fluoric acids. When it 

 came in contact with air, the gas deposited small red crys- 

 tals, which were those of chromic acid. 



Professor Berzelius repeated these experiments of M. Unver- 

 dorben, and he found that the experiment succeeded equally 

 well with common concentrated sulphuric acid. He collected the 

 gas in glass flasks covered with melted ' resin, and filled with 

 mercury. The gas had a red colour. It gradually attacks 

 the resin, deposits chromic acid in its mass, and penetrates 

 even to the glass, which it decomposes without change of 

 volume, the chrome being replaced by silicium. Ararao- 

 niacal gas introduced into it burns with explosion. Water dis- 

 solves it, and yields an orange-coloured fluid, which, evaporat- 

 ed to dryness in a platina dish, leaves as a residue pure 

 chromic acid. The fluoric acid volatilizes entirely. This 



VOL. IV. NO. 1. JAN. 1826. i 



