Chemical Science, 



acW. On repeating the experiments I have always obtained the 

 same results. — Bull. Univ. A. viii. 360. 



9. On Testing the Presence of Ammonia in a Substance. — Having 

 occasion to ascertain whether the action of a salifiable base upon a 

 body containing azote, was simply that of evolving ammonia, pre- 

 viously existing, or that of forming ammonia by the combination, M. 

 Plessin was induced to search lor a base which would effect the 

 former object, but not the latter. Potash, lime, magnesia, and 

 many other bodies do both, but the hydrated oxide of lead an- 

 swered the purpose very well. It gives no indication of ammonia 

 when put into contact with azotated substances not containing that 

 alkali ; even urea is not affected by it ; but being put in contact 

 with an ammoniacal salt, ammonia was instantly evolved, and ren- 

 dered evident by the visible fumes which arose upon the approxima- 

 tion of a little acetic acid. — Annales de Chimie, xxxvi. 177. 



10. Combination of Lime with Water. — According to M. Bel- 

 lani, when lime combines with water, notwithstanding the intense 

 chemical action which takes place and the heat evolved, there is no 

 ultimate condensation between the elements of the hydrate. Lime 

 was put into a matras, and then the vessel filled to the middle 

 of the neck with water ; the place of the surface of the water was 

 then marked, after which heat was applied and the lime converted 

 into a hydrate, no vapour being allowed to escape ; when the whole 

 was cool, the place of the surface was exactly in the same part of 

 the neck as at first. — Giornale de Fisica. 



11. Examination of Copper. Precipitation of Bismuth. — Mr. 

 Phillips says, " some samples of copper which I examined some 

 time since, contained 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 ; it contained no lead ; and upon the addition of 

 muriatic acid to a very dilute solution, slight precipitation took 

 place, which I at first imagined was occasioned, as in the former 

 case, by the presence of silver. I happened, however, to remem- 

 ber a fact mentioned in conversation some years since, and which I 

 have never met with in any chemical work — that a solution of bis- 

 muth, so dilute or so acid, that water would occasion no preci- 

 pitate in it, is decomposed by the addition of common salt or mu- 

 riatic acid ; and this I found to be the case in the present 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 neces- 

 sary, in order to determine its quantity, to supersaturate with am- 

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

 of bismuth precipitated.-— P^iY. Ma^» N. S. iii. 231. 



JAN.— MARCH, 1828, Q 



