192 ANNUAL OF SCIENTIFIC DISCOVERT. ,. 



The most accurate method of taking specific gravities is of course 

 the specific gravity bottle ; but a hydrometer, if well made, gives, 

 I find, numbers varying not more than lfroni those of the bottle, 

 while its use involves far less trouble and expense. 



As an indication of the extent to which confidence can be placed 

 in an igniting-point of petroleum, taken in the manner recom- 

 mendecf, I may state that two different observers, experimenting 

 at different times on three different specimens of petroleum placed 

 before them without distinguishing marks, gave igniting-points in 

 which the greatest limit of variation was 1. It would doubtless 

 be easy for an analyst, by processes of fractional distillation, to 

 obtain, even from safe petroleum, vapor that would be inflammable 

 at 60 F., or even at freezing temperatures; but it would be ab- 

 surd to regard such petroleum as dangerous, or to use such a fact 

 as evidence of the weakness of any method of determining the 

 igniting-point of refined petroleum. What I claim for the method 

 above described is, that it accurately shows the temperature at 

 which petroleum, as used by the public, is dangerous. It surely 

 is not too much to expect that the method will be adopted by the 

 trade, and that no mineral oil will be supplied to the public unless 

 guaranteed to give oif no inflammable vapor below 100 of Fah- 

 renheit's thermometer. Only by some such means will explosions 

 in lamps, etc., be avoided, explosions which are always alarming, 

 frequently the cause of loss of property by fire, and occasionally 

 resulting even in loss of life. Pharm. Jour, and Trans. 



NEW PROPERTIES OF ALUMINIUM. 



At a recent meeting of the Lyceum of Natural History, Dr. 

 Henry Wurtz read a paper upon " Some new Properties of Alumin- 

 ium, with the disco veiy of a new allotropic modification of this 

 metal." Dr. Wurtz is the discoverer of the use of sodium amal- 

 gam in the working of gold and silver ores, and in the develop- 

 ment of his process has had occasion to manufacture large quan- 

 tities of amalgam, with which he has tried numerous experiments 

 upon metals. 



The behavior of aluminium toward sodium amalgam revealed 

 to him certain new and surprising properties of the first-named 

 metal. In order to understand the nature of the discovery, it is 

 necessary to say a few words about the metal aluminium. Pro- 

 fessor Wb'hler, of Gb'ttingen, first prepared aluminium as a gray 

 powder in 1827. He gave its specific gravity as 2.5, and stated 

 that it decomposed water, but afterwards remarked that the metal 

 in solid form did not possess this property. 



The difficulty of preparing aluminium prevented the application 

 of the metals in the arts, until Deville improved the methods of 

 its manufacture and reduced its price to 10 or 12 dollars a 

 pound, when it suddenly assumed great importance and attracted 

 universal attention. 



Aluminium is a bluish white' metal, malleable, ductile, a remark- 

 able conductor of electricity, fusing at nearly the same tempera- 

 ture as zinc. Although it is with extreme difficulty that we can 



