190 
ME. Gk GrOEE ON HYDEOELTJOEIC ACID. 
was not raised above 450°Fahe. No permanent gas was evolved during the process. 
The product was a colourless fuming liquid, much less fuming than anhydrous hydro- 
fluoric acid, and did not corrode paraffin or platinum, but corroded vulcanized india- 
rubber rapidly. This liquid was electrolyzed by means of six Smee’s elements and two 
large platinum electrodes, during five hours, the liquid being in a covered narrow and 
deep platinum cup immersed in a freezing-mixture ; conduction occurred freely, and an 
odourless gas (doubtless ordinary oxygen) was freely evolved from the anode ; the anode 
was not corroded, and both electrodes were unaltered in weight. 
520 grains of anhydrous hydrofluoric acid was distilled from about 2000 grains of 
KF, HF in a platinum retort through a platinum tube surrounded by the freezing-mix- 
ture into a platinum bottle (surrounded by the same mixture) containing 334 T 7 grains 
of fibrous sulphuric anhydride ; the first contact of the two substances was attended by 
a hissing sound and evolution of great heat, and the resulting compound was a colourless 
liquid, of a less fuming character than either of the two substances alone. In this 
experiment it was necessary to cement the junctions near the receiver with the melted 
sulphur mixture (see p. 173), as paraffin is rapidly blackened by the vapours of sulphuric 
anhydride *. The compound formed in this case was probably analogous in some respects 
to partially hydrated sulphuric acid, 2HF taking the place of H 2 0, and corresponds to the 
third hydrate of sulphuric acid, or H 2 S0 4 , 2H 2 O. This liquid was also electrolyzed by 
means of platinum electrodes and ten Smee’s elements ; the conduction was moderate 
(less than with HF alone), and the anode was corroded. Sulphuric anhydride added to 
the mixture produced heat. 
To obtain an idea of the general chemical behaviour of the pure anhydrous acid, 
numerous substances (generally anhydrous) were immersed in separate portions of it in 
platinum cups, contained in a tin chilling-ease sunk deep in the freezing-mixture (see 
p. 173), and sometimes covered with plates of transparent fluor-sparf ; the temperature 
of the acid varied from 20° to 0° Fahr. It slightly dissolved bromine to a liquid of an 
orange colour ; iodine, carbon, boron, silicon, sulphur, selenium, tellurium (in powder), 
and phosphorus were unchanged. The noble and base metals were unaffected ; and even 
magnesium, aluminium, zinc, cadmium, tin, lead, reduced iron, arsenic, antimony, and 
bismuth in a state of fine powder did not cause any evolution of hydrogen. Sodium 
and potassium behaved much the same as with water, the latter producing vivid com- 
bustion. Nearly all the salts of the alkali and alkaline-earth metals produced strong 
chemical action. The acid produced violent chemical action with the following anhy- 
drides : — fused boracic, silicic (only when in fine precipitated powder, not with small gra- 
nules of quartz or even with fine white sand), sulphuric, phosphoric, molybdic, vanadic, 
and niobic anhydrides ; selenious and arsenious anhydrides dissolved freely ; antimonious, 
tungstic, and titanic anhydrides were either but little or not at all affected nor dissolved ; 
* Gun-cotton inflamed by contact with sulphuric anhydride. 
f I have obtained suitable vessels, plates, and stoppers of fluor-spar of Mr. J. Ttm, Speedwell Mine, Cas- 
tleton, Derbyshire, 
