THE ANALYST. 9 REMARKABLE EXPLOSIONS. ExpLosroN OF A DxAMoND.-At a recent meeting of the Academy of Natural Science8 of Philadelphia, Professor Leidy exhibited a black agate sleeve button, which had set in it centrally, raised in a gold setting, a rose diamond, about 7mm. broad. I t had been submitted to him by Mr. Kretzmar, a jeweller, who informed him that the person who wore it was recently leaning with his head upon his hand on E window ledge in the sun, when the diamond exploded audibly and with sufficient force to drive a fragment into his hand and another into his forehead.On examining the diamond the fractured surface, f o h ~ i n g a clearage plane, exhibited apparently the remains of a thin cavity such as is some- times to be seen in quartz crystrtls.The fracture also exposed a conspicuous particle of coal. Professor Leidy thought that the explosion had been due to the sudden expansion of some volatile liquid contained in the cavity, as frequently occurs in cavities in many minerals. Mi-. Goldsmith thought it possible that the liquid was carbonic acid, as he was impressed with the idea that diamonds originated from this material in the liquid condition.EXPLOSION OF CARBONIC Acm-Attention was recently directed in the French Academy to a case of explosion of carbonic acid which occurred in July last in one of the coal pits of Rochebelle (Gard). The10 THE ANALYST. coal strata there are much dislocated, and the carbonic acid, generated plentifully in the neighbourhood, and finding its way through natural passages, seems to have accumulated in certain parts with sufficient tension to explode with two loud detonations, driving a large quantity of fine coal into the galleries. Three men were asphyxiated, and two others were only able to throw themselves in a swooning state into the cage and be hauled up.That no flame was present (as in explosions of fire damp) is proved by the absence of burns on the bodies of the victims, the fact that blasting cartridges did not go off, &c. The gas is thought to have arisen from sulphurio acid (produced through oxidation of a stratified mass of pyrites) dissolving in subterranean waters, and finding its way down to triassic limestone.I n the works of M. Kuhlmann lately an alembic of platinum, about 90 centimetres diameter, used for producing daily some 6,000 to 7,000 kilog.of concentrated sulphuric acid, was exploded, the component pieces being shattered and thrown out. with bricks of the fireplace, 20 to 30 metres in different directions. Fortunately a slight hissing was observed a few seconds previously, so that the workmen had time to escape a terrible fate. The nature of the explosion If.Kuhlmann supposes to be as follows :-This platinum apparatus was being cleaned ; some 30 to 40 kilogrammes of concentrated sulphuric acid had been left in it ; on this some water had been admitted through the siphon, and the whole had been gently heated three or four hours. It is known that mixing sulphuric acid with water produces a good deal of heat ; in the present instance, combination is thought to have taken place instantaneously, at a pretty high temperature, generating a large amount of vapour. From data furnished by Fabre and Silbermann, it appears that 40 kilogrammes of acid at 18 deg., with water, is capable of producing instantaneously 18 to 20 cubic metres of vapour, and this is sufficient to explode a platinum vessel of about 300 litres capacity and only 2 to 3mm.thickness. As the combination occurred at about 100 deg., the force would be greater. M. Iiuhlmann has repeated the explosion several times in laboratory experimcnts, and he finds that it always occurs with great violence where the quantity of water is a t least ten equivalents for one of acid. In presence of the difficulty of mixing these two substances, which have a very great affinity, but the density of which is so different that they may remain several hours one on the other without mixture and consequent combination, the need of cautious management is obvious.