Notwithstanding this apparently successful result of the work, the line was cut asunder soon after the connection was completed on the rocks near Cape Grinez, the physical configuration of the French coast being very unfavorable. The precise point where the breakage took place was about two hundred yards out to sea, just where the twenty miles of electric line that had been laid down from Dover joins on to a leaden tube designed to protect it from the surge beating against the beach, and which also serves a similar purpose up the front of the cliff to the station upon the top. The leaden conductor, it would appear, was of too soft a texture to resist the oscillation of the sea, and thereby became detached from the coil of gutta-percha wire that was thought to have been safely encased in it. The occurrence was, of course, quickly detected by the sudden cessation of the series of communications, though it was at first a perplexing point to discover at what precise spot the wire was broken or at fault. This, however, was done by hauling up the line at intervals, a process which disclosed the gratifying fact, that, since its first sinking, it had remained in situ at the bottom of the sea, inconsequence of the leaden weights or clamps that were strung to it at every sixteenth of a mile. The experiment, as far as it has gone, proves the possibility of the gutta percha wire resisting the action of the salt water, of the fact of its being a perfect waterproof insulator, and that the weights on the wire are sufficient to prevent it being drifted away by the currents, and for sinking it in the sands.
The work at present has been suspended, but will be resumed again during the spring of 1851; a somewhat different plan, however, has been proposed to be followed from that at first adopted. Instead of one slender wire, it is intended to lay down cables inclosing four lines. These cables will be composed of gutta-percha, four or five inches in thickness, the whole encased in wire rope, chemically prepared, to protect it from rot, and kyanized. There will be two of these cables, each twenty miles long, and three miles apart, the whole weight representing 400 tons; and it is expected, when chained down in the bottom of the sea, they will be of sufficient consistency and strength to resist the anchor of a 120-gun ship. The expense of the cables is estimated at £40,000. It is thought that the whole work may be accomplished by May, 1851.—Annual of Scientific Discovery.
[ACTION OF SOLUTIONS OF CHLORIDES AND AIR ON MERCURY.]
We have given in previous Numbers the results of M. Mialhe's experiments on the action of chlorides on some mercurial compounds, and he states that he had nearly concluded his experiments when it occurred to him to try whether mercury itself would not be acted upon by this class of substances.
Experiment, he states, confirmed his suspicions, for he found that the solutions of the alkaline chlorides put into contact with mercury and atmospheric air always produced bichloride of mercury, the quantity of which was greater in proportion to the concentration of the solution of the chloride, and the more perfect state of division of the metal, but no effect is produced unless oxygen, that of the air being sufficient, is present.
1st Experiment.—Mercury treated with the solution of alkaline chlorides (described in our last Number as the assay liquor ), gave by stove heat 0·4 part of sublimate.
2nd Experiment.—The above repeated with the mercury finely divided by mucilage, yielded 0·7 part of sublimate.
The researches already detailed sufficiently prove, in the opinion of M. Mialhe, that the decomposing power of the alkaline chlorides is great, but they do not teach us anything as to their relative energy. The following experiments will supply this deficiency.
Hydrochlorate of Ammonia.—One hundred and twenty parts of hydrochlorate of ammonia and 30 parts of calomel were placed in an open bottle containg 1000 parts of distilled water, the temperature of which was gradually raised to 122° Fahr., and kept for half an hour; the sublimate produced amounted to 0·9 of a part.