ON HYDROFLUORIC ACID. 
651 
Numerous experiments were made of electrolysing the anhydrous acid with anodes of 
gas-carbon, carbon of lignum-vitae, and of many other kinds of wood, of palladium, 
platinum, and gold. The gas-carbon disintegrated rapidly ; all the kinds of charcoal 
flew to pieces quickly ; and the anodes of palladium, platinum, and gold were corroded 
without evolution of gas. The acid with a platinum anode conducted electricity much 
more readily than pure water; but with one of gold it scarcely conducted at all. 
These electrolytic experiments presented extreme difficulties, and were conducted in a 
platinum apparatus (shown by a figure) specially devised for the purpose. The parti¬ 
culars of the conditions and results obtained are described in the paper. Various mix¬ 
tures of the anhydrous acid with monchydrated nitric acid, with sulphuric anhydride, 
and with monohydrated sulphuric acid were also electrolysed by means of platinum 
anodes, the particulars and results of which are also described. 
To obtain an idea of the general chemical behaviour of the pure anhydrous acid, 
numerous substances (generally anhydrous) were immersed in separate portions of the 
acid in platinum cups, kept at a low temperature (0° to — 20° F.). The acid has 
scarcely any effect upon any of the metalloids or noble metals; and even the base 
metals in a state of fine powder did not cause any evolution of hydrogen. Sodium and 
potassium behaved much the same as with water. Nearly all the salts of the alkali 
and alkaline-earth metals produced strong chemical action. Various anhydrides (speci¬ 
fied) dissolved freely. Strong aqueous hydrochloric acid produced active effervescence. 
The alkalies and alkaline earths united strongly with the acid. Peroxides gave no 
effect. Numerous oxides (specified) produced strong chemical action, some of them dis¬ 
solving. Some nitrates were not chemically affected ; others (those of lead, barium, 
and potassium) were decomposed. Fluorides generally were unchanged ; but those of 
the alkali-metals and of thallium produced different degrees of chemical action, those of 
ammonium, rubidium, and potassium uniting powerfully. Numerous chlorides were 
also unaffected, whilst those of phosphorus (the solid one only), antimony (the per- 
chloride), titanium, and of the alkaline-earth and alkali metals were decomposed witji 
strong action, and generally with effervescence. The chlorates of potassium and sodium 
were also decomposed with evolution of chloric acid ; the bromides of the alkaline-earth 
and alkali metals behaved like their chlorides. Bromate of potassium rapidly set free 
bromine. Numerous iodides were unaffected ; but those of the alkaline-earth and alkali 
metals were strongly decomposed, and iodine (in some cases only) set free. The anhy¬ 
drous acid decomposed all carbonates with effervescence, and those of the alkaline-earth 
and alkali metals with violent action. Borates of the alkalies also produced very strong 
action. Silico-fluorides of the alkali metals dissolved with effervescence. All sulphides, 
except those of the alkaline-earth and alkali metals, exhibited no change; the latter 
evolved sulphuretted hydrogen violently. Bisulphite of sodium dissolved with efferves¬ 
cence. Sulphates were variously affected. The acid chromates of the alkali metals 
dissolved with violent action to blood-red liquids, with evolution of vapour of fluoride of 
chromium. Cyanide of potassium was violently decomposed, and hydrocyanic acid set 
free. Numerous organic bodies (specified) were also immersed in the acid ; most of the 
solid ones were quickly disintegrated. The acid mixed with pyroxylic spirit, ether, and 
alcohol, but not with benzole ; with spirit of turpentine it exploded, and produced a 
blood-red liquid. Gutta percha, india-rubber, and nearly all the gums and resins were 
rapidly disintegrated, and generally dissolved to red liquids. Spermaceti, stearic acid, 
and myrtle wax were but little affected, and paraffin not at all. Sponge was also but 
little changed. Gun-cotton, silk, paper, cotton-wool, calico, gelatine, and parchment 
were instantly converted into glutinous substances, and generally dissolved. The solu¬ 
tion of gun-cotton yielded an inflammable film on evaporation to dryness. Pine-wood 
instantly blackened. 
From the various physical and chemical properties of the anhydrous acid, the author 
concludes that it lies between hydrochloric acid and water, but is much more closely 
allied to the former than to the latter. It is more readily liquefied than hydrochloric 
acid, but less readily than steam : like hydrochloric acid it decomposes all carbonates; 
like water it unites powerfully with sulphuric and phosphoric anhydrides, with great 
evolution of heat. The fluorides of the alkali metals unite violently with hydrofluoric 
acid, as the oxides of those metals unite with water; the hydrated fluorides of the alkali 
metals also, like the hydrated fixed alkalies, have a strongly alkaline reaction, and are 
capable of expelling ammonia from its salts. It may be further remarked that the 
2 Y 2 
