ME. G. GOEE ON HYDEOELU OEIC ACID. 
193 
Oxalic acid, oxalate, and benzoate of ammonium were but little affected. Paraffin was 
unaffected. Benzole would not mix with the acid. Spirit of turpentine exploded and 
produced a blood-red liquid. Gutta percha, india-rubber, ebonite, parkesine, white wax, 
sealing-wax, gum-arabic, amber, copal, dammar, gamboge, juniper, kino, kowrie, shellac, 
and ordinary resin were rapidly disintegrated, and in nearly all cases quickly dissolved 
to red liquids. Spermaceti, stearic acid, and myrtle wax were but little affected. Caf- 
feine, indigo, sugar of milk, and cane-sugar dissolved freely and rapidly. Gun-cotton 
dissolved instantly to a colourless liquid, which left an inflammable film on evaporation. 
Silk also instantly dissolved to a glutinous colourless liquid. Paper, cotton-wool, calico, 
gelatine, and parchment were instantly converted into glutinous substances and dissolved. 
Horn instantly expanded to a bulky white mass. Irish moss, German-tinder, and flannel 
were less rapidly affected, and sponge was less affected than any other porous organic 
substance. Pine-wood instantly blackened. 
The chemical behaviour of such of these numerous substances with the anhydrous 
liquid acid as have been further examined will be more fully described in their respective 
places. 
The gaseous acid carbonized cork, and acted upon wood, paper, gutta percha, india- 
rubber, vulcanized india-rubber, andbees-wax more slowly, but in much the same manner 
as the liquid acid ; sealing-wax absorbed the gas and became soft and disintegrated. It 
did not act upon carbon, sulphur, or selenium, nor, if perfectly dry, did it act upon glass, 
as has been already stated (see pages 184 & 192). 
From the various experiments already described, we may conclude that hydrofluoric 
acid is by its properties placed between hydrochloric acid and water, but is much more 
closely allied to the former than to the latter. It is more readily liquefied than hydro- 
chloric acid, but less readily than steam : like hydrochloric acid it decomposes all car- 
bonates ; like water it unites powerfully with sulphuric and phosphoric anhydrides, with 
great evolution of heat. The fluorides of the alkali metals unite violently with anhydrous 
hydrofluoric acid, like the oxides of those metals unite with water ; the hydrated fluo- 
rides 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 re- 
marked that the atomic number of fluorine lies between that of oxygen and chlorine ; 
and the atomic number of oxygen, added to that of fluorine, very nearly equals that of 
chlorine. 
B. Aqueous Hydrofluoric Acid. 
Ordinary hydrofluoric acid is very impure ; it usually contains large quantities of sul- 
phuric acid (distilled over by excess of heat), much sulphurous acid (from action of the 
oil of vitriol upon the iron retort), some hydrofluosilicic acid (from silica in the spar), 
arsenic (from the sulphuric acid), and small amounts of hydrochloric acid, iron, lime, 
and other fixed matters. A sample manufactured in Birmingham, of specific gravity 
1-399, was found by analysis to contain 29-58 per cent, of H 2 S0 4 , and 0-5 per cent, of 
ignited fixed matter which had been previously precipitated by excess of ammonia ; it 
