On hydrofluoric acid : on a momentary molecular change in iron wire : and on the development of electric currents by magnetism and heat / by G. Gore.

  • Gore, George, 1826-1909.
Date:
1869
Catalogue details

Licence: Public Domain Mark

Credit: On hydrofluoric acid : on a momentary molecular change in iron wire : and on the development of electric currents by magnetism and heat / by G. Gore. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    A number of attempts were made, finally with success, to determine the molecular volume of the pure anhydrous acid in the gaseous state, the acid in these cases being prepared by heating pure anhydrous fluoride of silver with hydrogen in a suitable platinum apparatus over mercury. Particulars are given of the apparatus employed and of the manipulation. The results obtained show that one volume of hydrogen, in uniting with fluorine, pro- duces not simply one volume of gaseous product as it does when uniting with oxygen, but two volumes, as in the case of its union with chlorine. The gaseous acid transferred to glass vessels over mercury did not corrode the glass, or render it dim in the slightest degree during several weeks, pro- vided that moisture was entirely absent. The author concludes that the anhydrous acid he has obtained is destitute of oxygen, not only from the various analyses and experiments already re- ferred to, but also, 1st, because the double fluoride from which it was pre- pared, when fused and electrolyzed with platinum electrodes, evolved abundance of inflammable gas at the cathode, but no gas at the anode, al- though oxides are by electrolysis decomposed before fluorides ; 2nd, because the electrolysis of the acid with platinum electrodes yielded no odour of ozone, whereas the aqueous acid of various degrees of strength evolved that odour strongly ; and, 3rd, because the properties of the acid obtained from hydrogen and fluoride of silver agree with those of the acid obtained from the double salt. He considers also that the acid obtained from pure fluor-spar and monohydrated sulphuric acid heated together in a platinum retort is free from oxygen and water. The specific gravity of the anhydrous liquid acid was several times de- termined, both in a specific-gravity bottle of platinum, and also by means of a platinum float submerged and weighed in the acid. Concordant and reliable results were obtained; the specific gravity found was 0‘9879 at 55° Fahr., that of distilled water being=T000 at the same temperature. The anhydrous acid was much more volatile than sulphuric ether. Its boiling-point was carefully determined in a special apparatus of platinum, and was found to be 67° Fahr. Not the slightest sign of freezing occurred on cooling the acid to —30° Fahr. (= — 340,5 C.) ; and it is highly probable that its solidifying temperature is a very great many degrees below this. Its vapour-tension at 60° Fahr. was also approximately determined, and was found to be =7'581bs. per square inch. On loosening the lid of a bottle of the acid at 60° Fahr., the acid vapour is expelled in a jet like steam from a boiler ; this, together with the low boiling-point, the extremely dangerous and corrosive nature of the acid, and its great affinity for water, illustrates the very great difficulty of manipulating with it and retaining it in a pure state. Nevertheless, by the contrivances described, and by placing the bottles in a cool cellar (never above a temperature of 60° Fahr.), the author has succeeded in keeping the liquid acid perfectly, without loss and unaltered, through the whole of the recent hot summer. The electrical relations of different metals &c. in the acid were found to