Hitherto it has been thought that to produce a good black dye the co-operation of a metallic substance or of a chlorate, or both combined, was indispensable. The question arose: Were those ingredients really indispensable? Mr Rosenstiehl first shewed that the metal might be dispensed with, and recently, as may be seen in the Annales de Chimie et de Physique, Mr Coquillion has proved that the chlorate is not required, for in the one case as in the other, the use of 'nascent' or active oxygen will effect the desired object. We are informed that the fact observed by the French chemist 'is an elegant demonstration of the action of active oxygen upon aniline salts; that it will perhaps enable us to obtain blacks derived from aniline in a state of greater purity, and to hasten the moment when we shall know their elementary composition; a question which, in view of its great interest, has been proposed for a prize by the Industrial Society of Mulhausen.'
Mr Cornet, whose name has been mentioned above, in a mathematical discussion of the question, says that compressed air would be largely used in mining operations 'were it possible to keep the temperature of the air from rising during compression much above that of the atmosphere, and from falling during expansion to the temperature of freezing water.' And he thinks that he has found 'the means for attaining this end in the use of water-spray, which could be introduced into the cylinder of the compressor, and into that of the machine using the air in the mine.' The practical details are not yet made known; but if they succeed, 'the use of compressed air in mines will soon become general, and the problem of mining at any depth will be solved.'
One part of the method devised by Mr Cornet had been previously thought of; for in 1875 an air-compressor was working in the St Gothard tunnel, of which it was said: 'The heat produced by compression is reduced by the circulation of cold water in the walls of the cylinder, in the interior of the piston and its rod; and an injection of water-spray at the two extremities of the cylinder completes the cooling.' When the compressors were at work they supplied to the tunnel fifteen cubic mètres of air per minute.
When messages were first sent by telegraph, many persons were exceedingly puzzled to understand how they were sent; and now the telephone has come to disturb them with another puzzle. But scientific men have long known that 'galvanic music,' as it is called, was discovered forty years ago, that an electro-magnet on being suddenly magnetised or demagnetised gives out audible sounds, and that many notices of the curious fact were printed in English and foreign journals. Professor Graham Bell, whose experiments have been already mentioned in these pages (ante [208], [415]), succeeded in making the sounds, which were commonly very faint, audible to a large number of persons. This was accomplished, as he explains, 'by interposing a tense membrane between the electro-magnet and its armature. The armature in this case consisted of a piece of clock-spring glued to the membrane. This form of apparatus,' he continues, 'I have found invaluable in all my experiments. The instrument was connected with a parlour organ, the reeds of which were so arranged as to open and close the circuit during their vibration. When the organ was played, the music was loudly reproduced by the telephonic receiver in a distant room. When chords were played upon the organ, the various notes composing the chords were emitted simultaneously by the armature of the receiver.'
'The simultaneous production of musical notes of different pitch by the electric current,' continues Professor Bell, 'was foreseen by me as early as 1870, and demonstrated during the year 1873. Elisha Gray of Chicago, and Paul La Cour of Copenhagen, lay claim to the same discovery. The fact that sounds of different pitch can be simultaneously produced upon any part of a telegraphic circuit is of great practical importance; for the duration of a musical note can be made to signify the dot or dash of the Morse alphabet; and thus a number of telegraphic messages may be sent simultaneously over the same wire without confusion, by making signals of a definite pitch for each message.'
By instalments of news from the Pacific we hear of the tremendous earthquake that occurred last May; but for precise details we shall have to wait until reports are published in the scientific journals of the United States. Meanwhile, we learn that the great volcano of Kilauea in Hawaii began to be restless on the first of the month; a few days later huge columns of lava were thrown up, vehement jets of steam burst forth from a long range of fissures, and all the startling phenomena of a mighty eruption, including drifts of Pele's hair, were observed. This evidence of disturbance deep down in the earth was corroborated by an earthquake, which about half-past eight on the evening of the 9th terrified and devastated the coast of Peru, and occasioned greater ruin than the similar calamity in 1868. Iquique is said to be completely destroyed, and other towns and cities along two hundred miles of coast suffered more or less severely. As usual, the commotion of the land produced a commotion of the water, and the sea rolling great waves upon the shore, intensified the havoc. The waves varied in height from ten to sixty feet; and we are told that 'four miles of the embankment of the railway were swept away;' and that 'locomotives, cars, and rails were hurled about by the sea like so many playthings.'
Also, as is usual in such catastrophes, the earthquake wave was propagated; and between four and five of the morning of the 10th, it (that is the sea) rushed upon the Hawaiian Islands in waves varying from three to thirty-six feet in height. Thus in eight hours the resistless oscillation had traversed the five thousand miles which separate the islands from the South American continent.
From this brief sketch it is obvious that there is much in this calamitous visitation to interest the physicist and geologist as well as the philanthropist. Information will in all probability be communicated from other places until the remotest points at which the disturbance was felt shall have been ascertained.
As relating to this subject we remark that the hair of Pele—a Hawaiian goddess—above mentioned can be produced artificially in a blast furnace. It has been described in former pages of this Journal as 'slag cotton.'