272 



Art. V. Contributions towards the Chemical Know- 

 ledge of Mineral Substances. By the late Martin 

 Henry Klaproth. Vols. IV. V. and VI. 



[It has, we believe, beeu frequently regretted that no English translation 

 of the three last volumes of Klaproth's Analytical Essays has hitherto 

 appeared ; in compliance, therefore, with tbe suggestion of several of our 

 chemical readers, we propose to lay before them an account of the 

 principal analyses contained in those volunaes ; giving sometimes an 

 entire translation of the original, at others an abstract, and sometimes 

 merely the results of the author's experiments ; being in these respects 

 guided by the novelty and importance of the details, and by the origi- 

 nality and efficacy of the manipulations. We trust that the chemical 

 student will especially derive advantage from an acquaintance with the 

 latest labours of this celebrated and accurate analyst.] 



1 . Chemical Examination of Electrum, a native Alloy of Gold 

 and Silver. 



The term electrum, commonly applied to amber, has also been 

 used to denote an alloy of gold and silver. " Omni auro inest 

 argentum vario pondere : uhicunque quinta argenti portio est 

 ELECTRUM vocatur*," says Pliny ; whence it would appear that 

 the term is only properly applicable to the alloys containing 

 excess of gold, which is the case with the electrum of Schlan- 

 genberg in Siberia, where it occurs native, of a pale gold colour, 

 in small plates, imperfect cubes, Sfc, associated with a grey 

 coarse-grained sulphate of baryta, and also with a splintery 

 variety of grey horn-stone : the matrix of the specimen employed 

 in the following analysis was sulphate of baryta. To separate 

 any free silver or gold it was first digested in nitric acid, to 

 which muriatic acid was afterwards added ; it was then fused 

 -with borax. 



A piece of the electrum thus purified and weighing 25 

 grains, was beaten flat and boiled in nitric acid, which 

 exerted no action upon it ; an equal portion of muriatic acid 

 was then added, but still without effect. 



b. The electrum was then fused with the addition of its 

 weight of silver, laminated, and boiled with nitric acid, which 



* Lib. :!LXxiii. cap. iv. sect, xxiii. 



