37S 



Scientific Intelligence. 



conclusion that organic substances are the true cause of their colour. His. 

 experiment^ were made by digesting the specimens with hydrochloric 

 acid, determining the carbon in the residue; and assuming that it exists 

 there in the form of a humus acid, containing 58 per cent, of carbon, he 

 calculates the total quantity of organic matter they contain. The follow- 

 ing table gives his results : — 



Dolomite from Tuttomaggi, . 

 Do. another specimen, . . 

 Dolomite from Igo Pank, . . 

 Do. do. Ojo Pank, . . 

 Do. do. Koggowa Sar, . 

 Dolomitic limestone from Hoi- 1 



lenhagen, near Salzuflen, J 

 Dolomite from Ojo Pank, with ) 



black incrustation, . . J 

 Dolomite from Koggowa Sar, ) 



with black incrustation, / 



Residue, 

 insoluble 

 in acid. 



Carbon. 



Organic 



matter. 



Iron 

 pyrites. 



14-90 

 14-11 

 13-00 

 25-40 



35-20 



26-61 

 23-90 



29-80 



0-102 

 0-084 

 0-101 

 0-160 

 0-213 



0-131 

 0-220 

 0-463 



0-176 

 0-145 

 0-174 



0-276 

 0-367 



0-226 

 0-379 



0-798 



0-35 

 0-31 

 0-35 

 0-31 

 1-46 



none, 

 not exam, 

 notexam. 



By a comparison of these experiments with the colour of the speci- 

 mens, the author dra\v r s the conclusion that it is due to the organic matter, 

 and not to the pyrites. — (Journal fur Practische Chemi*, vol. lxiii., 

 p. 193.) 



[Our own observations have led us to a conclusion similar to that stated 

 by Petzholdt. We have found that some dark-coloured limestones yield 

 appreciable quantities of organic matter, amounting in some instances to 

 about one per cent., without a trace of iron pyrites. In many instances, 

 however, the organic matter is accompanied by pyrites, and this is re- 

 markably seen in some varieties of black marble. The pyrites in such 

 limestones may probably be traced to the collection of sulphate of iron 

 during the decomposition of the organic remains which they contain. — 

 Edit. Phil. Journal.'] 



CHEMISTRY. 



Preparation and Properties of Aluminium. By M. St Clair Deville. 

 Some time since it was announced that Deville had succeeded in procur- 

 ing aluminium in abundance, and by a process which would permit its 

 use in the arts. It now appears that the processes employed by Deville 

 are merel}'' modifications of those already known, sodium and the galvanic 

 battery being the agents employed to reduce the chloride of aluminium. 

 These processes are manifestly so expensive as to render it unlikely that 

 aluminium will be applied to any economic uses, but the author has been 

 enabled to describe more fully than lias before been done the properties 

 of the metal. It is a fine white metal, with a high metallic lustre. Its 

 hardness, when cast, is about the same as that of pure silver, but is in- 

 creased by pressure. It is highly malleable and ductile, conducts electri- 

 city about eight times as well as iron, and is slightly magnetic. It crys- 

 tallizes readily by fusion, and its crystals appear to belong to the regular 

 system. It melts at a temperatuie above that of zinc, but lower than 

 silver, and the author attributes the excessively high melting point found 

 by Wohler to the presence of platinum in the specimen examined by him. 

 Its sp. gr. is 2*56, which is increased to 2-67 by rolling. It is unaltered by 

 «iir and oxygen, even at the melting point of gold. It is without action 

 in water, at ordinary temperatures, at 212°, and even at a lower heat ; 



