Parkes's Chemical Catechism, hj Bray ley. 217 



from 13*5 to less than 3; while all its metallic character* of colour, lustre, 

 opacity, and conducting powers, remain unimpaired." 



Retaining both these statements, the Editor annexes the subjoined 

 explanation : 



" The history of this supposed amalgam of mercury with a metallic sub- 

 stance apparently derived from the ammonia or its elements, is still involved 

 in obscurity; and as it is of considerable importance in a theoretical point 

 of view, it cannot be passed over in silence at the present time. The above 

 statements, both in the text and note, are agreeable to the results obtained 

 by Sir H. Davy, who repeated the experiments of Berzelius and his coadju- 

 tors; but he discovered, also, a more simple method of obtaining the sup- 

 posed amalgam, without the aid of galvanism. He found that when an 

 amalgam of mercury with potassium (the metallic base of the alkali potash) 

 is placed in contact with a solution of ammonia or with any moistened ara- 

 inoniacal salt, it enlarges to eight or ten times its original bulk, becoming a 

 8oft solid, and acquiring the properties described in the preceding note. It 

 was conceived both by Berzelius and Davy, that this singular result was pro- 

 duced by the union of new metallic matter with the mercury, — that it was 

 truly an amalgam of a new metal, arising from the reduction of the ammo- 

 nia or its elements to a metallic form ; and they accordingly drew some 

 important inferences from the fact of its production, respecting the inti- 

 mate nature of ammonia as well as that of its constituents hydrogen and 

 nitrogen. But neither of these chemists could succeed in separating the 

 supposed new metal from the mercury, so as to exhibit it in an isolated 

 state, which of course threw great doubt on the validity of their theoretical 

 inferences; and the subject remained enveloped in mystery and difficulty. 

 Some experiments not long since made by Mr. Daniell, however, afford 

 strong grounds for believing, in the opinion of many chemists of the present 

 day, that no metallization of the ammonia or its elements in reality takes 

 ])lace, and that the results obtained by Berzelius and Davy depend merely 

 on a mechanical alteration of the arrangement of the particles of the mer- 

 cury, and the entangling and retaining among them of small portions of am- 

 monia or its constituent gases ; and Mr. Daniell has obtained a substance 

 bearing great resemblance to the supposed amalgam, without the presence 

 of ammonia. Subsequent experiments by Mr. Brande lead to a similar 

 conclusion. If, therefore, this view of the subject shall hereafter be fully 

 confirmed, it will be proper to regard the statements upon it in the text 

 and note above, not as affording any information respecting the composition 

 of the alkali ammonia, but as describing merely a curious alteration in the 

 mechanical condition of mercury, which can also be produced by other 

 means. At the same time it must be admitted that absolutely decisive ex- 

 periments on the supposed ammoniacal amalgam are still wanting; and it 

 seems to be due to Berzelius and Davy that the question should be set at 

 rest, by a series of delicate experiments instituted for the purpose. Those 

 who wish for further information upon it, are referred to Davy*s FAern. 

 Chem. Phil, pp.473, 481 ; Thomson's Inorganic Chemistry, vol. i. p. 146; 

 and the Journal of the Royal Institution, vol. i. pp. 12, 251, and 548. 



We have already stated that one of the novelties in this work is 

 the history of that interesting class of bodies the vegeto-alkalies : 

 after a general account of them, the specific properties and applica- 

 tions of the most important are detailed ; and appended to a notice 

 of the poisons deriving their effects from Stryclmiay we find the fol- 

 lowing critical remarks on the two poisons of Java frequently con- 

 founded together by chemical writers under the appellation of Upas, 

 which point out an important distinction : — 



Third Seri€.r. Vol. 6. No. 33. March 1835. 2 F 



