Intelligence and Miscellaneous Articles. 231 



monia, which at first precipitates both oxides in the state of carbon- 

 ate j and when added in excess, redissolves the carbonate of bismuth. 

 The carbonate of lead is to be washed in the filter with a solution of 

 carbonate of ammonia, in order to dissolve any adhering carbonate of 

 bismuth ; the washing is to be finished with warm water, in order to 

 dissolve all the carbonate of ammonia used in the washing. 



The alkaline liquor containing the oxide of bismuth, is to be satu- 

 rated by an acid, and then ammonia is to be added in excess ; all the 

 oxide of bismuth is precipitated, and after washing on a filter it is to 

 be dried and weighed. 



There is another method, which is perhaps more simple, but not so 

 exact. — Boil the alkaline liquor and evaporate to diyness, wash it 

 and filter in order to collect the oxide of bismuth. But this method is 

 inconvenient, because the oxide of bismuth adheres to the vessel in 

 which the solution is evaporated. 



An alloy of equal weights of lead and bismuth gave by analysis 

 49*1 of the former metal, and 496 of the latter j the loss being 1*3 

 per cent. The nitrate of lead and oxide of bismuth separated by this 

 process were both pure. 



The fusible compound of 8 parts bismuth, 5 lead, and 3 tin, ana- 

 lysed with nitric acid, left the oxide of tin on the filter : the oxides of 

 bismuth and lead were separated as above directed j 16 parts yielded 

 bismuth 7*98, lead 4*95, tin 3 5 the loss of the operation amounting 

 to .It, of the whole. — Ann. de Chim. xxxvi. p. 333. 



EXAMINATION OF COPPER. 



Some samples of copper which 1 examined some time since, con- 

 tained a small portion of silver, without any other impurity which I 

 could detect : lately, some other samples have been put into my hands, 

 in order to determine the cause of their being complained of. The 

 copper was dissolved in dilute nitric acid, used in excess j it contained 

 no lead, and upon the addition of muriatic acid to a very dilute solu- 

 tion, slight precipitation took place, which I at first imagined was oc- 

 casioned, as in the former case, by the presence of silver. I happen- 

 ed, however, to remember a fact mentioned in conversation some 

 years since, and which 1 have never met with in any chemical work, — 

 That a solution of bismuth so dilute or so acid that water would oc- 

 casion no precipitation in it, is decomposed by the addition of com- 

 mon salt or muriatic acid ; and this I found to be the case in the pre- 

 sent instance : the precipitate was small in quantity, not amounting 

 to one per cent for the copper employed, and it differed from chloride 

 of silver in very readily passing through filtering paper. I found it 

 necessary, in order to determine its quantity, to supersaturate with 

 ammonia, by which the oxide of copper was dissolved, and the oxide 

 of bismuth precipitated. R. P. 



ON EFFLORESCENCE. 



The following observations are by M. Gay Lussac. Many salts 

 when exposed to the air, are well known to effloresce j that is, they fall 

 to powder and lose their water of crystallization j and it is generally 



supposed 



