Mr. Grove on some Electro-Nitrogarets. 103 



nitroguret or ammoniuret of mercury bears a physical resem- 

 blance to an amalgam, might we not, upon the same principle, 

 assume many other elements ? As a theoretical question in the 

 mind of an experimenter, it can do no harm ; but as a recog- 

 nized base, I cannot but think it may tend to mislead. 



Another class of facts explained by the experiments above 

 detailed, are those exhibited in the decomposition of ammonia 

 during its passage over heated metals, first observed by, I be- 

 lieve, Berthollet, who remarked, that iron subjected to this 

 process became brittle, but did not change in weight. The- 

 nard, in similar experiments with iron, copper, silver, gold and 

 piatina, could not detect an increase in weight of above j^o tn » 

 Savart observed an increase of about y^^th. Despretz, how- 

 ever, although in his first experiments he could get no greater 

 increase than Savart, yet on a repetition found that in the case 

 of iron, and iron only, he could increase its weight 1 1 per cent. ; 

 he does not state the reason of his first failures, or of his subse- 

 quent success. 



These somewhat discordant results appear to receive an easy 

 explanation by my experiments, an explanation, indeed, first 

 theoretically suggested by Ampere, viz. that in passing heated 

 ammonia over the metals a nitroguret was formed and im- 

 mediately decomposed; that thus the physical structure of the 

 metals was changed without any notable increase of weight 

 or chemical alteration. 



Before concluding this paper, I ought not to omit a pas- 

 sage in one of Mr. DanielFs papers, which, upon a search made 

 subsequent to my experiments, is the only one I have found 

 bearing upon them. After stating some results with his con- 

 stant battery charged with muriate of ammonia on the zinc 

 side of the diaphragm, and sulphate of copper on the copper 

 side, he makes the following remark: — 



" There were no indications of free ammonia in the ex- 

 terior cell ; the precipitated copper, however, did not exhibit 

 the beautiful, bright, pink hue which it ordinarily presents, 

 but was of a dull, grayish, earthy appearance, resembling that 

 of copper over which ammoniacal gas has been passed at a 

 red heat, and probably contained some combined nitrogen. 

 I had not, however, time to examine a compound which is 

 worthy of further investigation." 



All the copper nitrogurets which I have formed have had 

 a chocolate colour, and the nearest substance to which I can 

 liken them is the coagulum of the blood ; the grayish colour 

 remarked by Professor Daniell proceeded probably from 

 some zinc being precipitated with the copper, or possibly the 

 temperature at which he wrought (124°) occasioned some dif- 



