ME. G. GOEE ON HYDEOFLTJ OEIC ACID. 
175 
colourless and transparent liquid at 60° Fahr., very thin and mobile, extremely volatile, 
densely fuming in the air at ordinary temperatures, and attracted water 
greedily from the atmosphere. It was perfectly retained in platinum 
bottles, the bottles having a flanged mouth, a platinum plate coated on its 
lower side with the paraffin mixture (see page 174) being tightly secured 
to the flanged mouth by eight clamp screws (see figure 4). The acid must 
be kept in a cool place, not above a temperature of 60° Fahr., otherwise 
it is very likely to burst the bottle ; and a freezing-mixture should always 
be at hand whilst experimenting with it. 
According to Lou yet'* anhydrous hydrofluoric acid, obtained by distilling 
oil of vitriol and fluor-spar, and redistilling the condensed product with 
anhydrous phosphoric acid, is a gaseous substance and does not liquefy at 
— 12° C. (=+10 o, 4Fahr.) under ordinary atmospheric pressure ; it fumes 
very strongly in the air, is rapidly condensed by water, has scarcely any action upon glass, 
and might probably be collected in glass vessels over mercury. According to FREMYf 
(who states that he assisted at the performance of M. Louyet’s experiments, and did 
not consider the results satisfactory), the dehydration effected by means of anhydrous 
phosphoric acid is not complete. He states that anhydrous hydrofluoric acid obtained 
by the distillation of dry double fluoride of hydrogen and potassium is gaseous at the 
ordinary temperature, but may be condensed at —20° C. by a mixture of ice and salt ; it 
is then a very fluid liquid, volatilizing when removed from the cooling mixture, acting 
very powerfully upon water, diffusing white fumes in the air with an intensity like that 
of fluoride of boron, and, contrary to M. Louyet’s assertion, attacks glass rapidly J. 
To ascertain, therefore, whether the liquid I had thus obtained was really anhydrous 
or not, I made the following analytical experiments: — 1st. I took 100 grains of the 
recently and well-dried double fluoride (which soon attracts a little moisture from the 
air), and heated it gently with constant motion in a platinum dish until it was all fused ; 
it evolved an acid odour, and lost 08 grain in weight. I now again slowly fused it, 
gradually increasing the heat until at an incipient red heat it was quite solid and evolved 
no more acid odour, then cooled it under a cover and weighed quickly ; its loss was 
now increased to 25 ’5 7 grains, the calculated theoretic loss of anhydrous hydrofluoric 
acid being 25 ‘59 grains, assuming the salt to be KF, HF. 
K =39-1 
F =19-0 
HF=2(M) 
KF, HF=78T 
* Comptes Bendus, yol. xxii. p. 960 ; also Gmelin’s Handbook of Chemistry, vol. ii. p. 361. 
f Comptes Bendus, No. 9, Eeb. 27th, 1854; also * The Chemist,’ June 1854. 
t Fremy also obtained the anhydrous acid by heating fluoride of lead (contained in a charcoal boat within a 
platinum tube) in a current of dry hydrogen, and Deyllle obtained the dry acid by passing hydrochloric-acid 
gas oyer highly heated fluor-spar (Comptes Bendus ; also Chemist, New Series, yol. iy. p. 330, and yol. ix. p. 556). 
2 b 2 
Fig. 4. 
