414 Miscellaneous Intelligence. 



1.060 of the succinate of lead gave 0.995 sulphate of lead. It is 

 supposed that a half proportion of water is contained in the above 

 succinic acid, and abstraction being- made of its elements, the acid 

 then agrees in composition with that which BerzeHus analyzed in 

 combination with oxide of lead. .<;i[ 



When tl]e mellitate of ammonia was heated in a glass tube, it was 

 decomposed, giving pecuhar results, there being first water, then 

 hydrocyanic acid, and, finally, a sublimate of brilliant green crystals, 

 which dissolved with difficulty in water, and produced a bitter solu- 

 tion. — Annates de Chimie, xliii. p. 200. I .^j g/BinJBa 



i ^ 6. Decomposition of Carbonic Acid by Metals. Despretz. — Car-*- 

 bonic acid presents the same phenomena with heated metals as 

 water. Iron, zinc, and tin, reduce it to carbonic oxide, and carbonic 

 oxide reduces the oxides of these three metals. The oxide of car- 

 bon had been prepared from a heated mixture of oxalate of potash 

 and sulphuric acid, and deprived of any acid it might carry over, by 

 washing in an alkaline solution. 



M. Dulong has also observed the reduction of carbonic acid to 

 carbonic oxide by zinc, and the reduction of the oxide of zinc to the 

 metal, by carbonic oxide. — Annates de Chimie, xliii. 222. 



7. Decrepitating Common Salt — Condemation of Gas in it. 

 Dumas. — M. Dumas has examined and described a very curious 

 effect which occurred when some rock-salt, obtained from the mine 

 of Wieliczka, in Poland, and given to him by M. Bout^, was put into 

 water. It decrepitated as it dissolved in the water, and gradu- 

 ally evolved a sensible portion of gas. The bubbles of gas were 

 sensibly larger when the decrepitations were stronger, and the latter 

 frequently made the glass tremble. This salt owes its property of 

 decrepitating to a gas, which it contains in a strongly-compressed 

 state, although no cavities are sensible to the eye. When the 

 experiment was made in perfect darkness no light was disengaged. 

 The gas disengaged is hydrogen slightly carbonated ; when mixed 

 with air it burns by the approach of a light. 



'* This disengagement of gas will assist in explaining the numerous 

 accidents which have happened from fire-damp in salt-mines. 

 Several portions of the salt were nebulous, others were transparent. 

 The nebulosities indicated the existence of numerous minute cavities, 

 probably filled with condensed gas, and, in fact, a nebulous fragment, 

 dissolved in water, gave more gas than an equal-sized fragment of 

 the transparent salt. ■' '^ 



This new fact, described by M. Dumas, shews how frequent, in 

 the course of geological accidents, are the phenomena to which are 

 due the accumulation of gas in the cavities of mineral substances, 

 and how varied are the substances upon which these phenomena 

 have been exerted. M. Dumas has endeavoured to reproduce, salt 



