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in general, is left, than the original weight of the platina ; and ad- 

 mits that even a diminution of weight may be sometimes observed. 

 Before the precipitate has been exposed to heat, it may be dissolved 

 in nitro-muriatic acid more easily than platina itself. 



The second experiment is to show that when a mixed solution of 

 platina and mercury is precipitated by metallic iron, a precipitate 

 nearly equal to the sum of the two former metals is generally ob- 

 tained, the properties of which appear to be similar to those of the 

 precipitate obtained in the first experiment. 



We learn, from the third experiment, that when an amalgam of 

 platina, formed by means of the ammoniacal muriate of that metal, 

 according to the method of Count Mussin Pushkin, is exposed to 

 heat, a metallic powder remains, which is soluble in nitro-muriatic 

 acid, and affords a copious precipitate by means of green sulphate of 

 iron. 



The fourth experiment states, that if sulphur is added to the in- 

 gredients used in the formation of the above-mentioned amalgam, 

 and the whole treated as before, the precipitate caused by green sul- 

 phate of iron is more considerable. 



The fifth experiment informs us, that if sulphur is rubbed with 

 ammoniacal muriate of platina, the mixture may be melted on a sand 

 bath. If mercury is then added to the melted mass, and the whole 

 exposed to a strong fire, a button remains, which, being dissolved in 

 nitro-muriatic acid, gives a precipitate, as before, with the green 

 sulphate of iron. 



In the sixth experiment we are told, that if sulphuretted hydrogen 

 is passed through a mixed solution of platina and mercury, and the 

 precipitate afterwards melted with borax, the button will not contain 

 any sulphur. Green sulphate of iron causes a precipitate in the so- 

 lution of this button. 



The seventh experiment serves to show that phosphate of am- 

 monia, when added to a solution of platina and mercury, causes a 

 precipitate, the solution of which is acted upon by green sulphate of 

 iron. 



By the eighth experiment it appears, that if the precipitate formed 

 by adding nitrate of mercury, at the minimum of oxidizement, to 

 muriate of platina be washed, reduced, and afterwards dissolved in 

 nitro-muriatic acid, another precipitate may be produced by means 

 of green sulphate of iron. 



The ninth experiment relates to the action of recent muriate of 

 tin, which Mr. Chenevix says is one of the most delicate tests in 

 chemistry, detecting the presence of mercury. If a single drop of 

 neutralized nitrate or muriate of mercury is put into 500 grains of 

 water, the addition of muriate of tin causes the liquor to become 

 turbid, and to assume a smoke-gray colour. And even if the above 

 liquor is diluted with ten times its weight of water, the effect is still 

 sensible. But if recent muriate of tin is poured into a solution, not 

 too much concentrated, of platina and mercury, it can hardly be di- 

 stinguished from a simple solution of platina. If, however, too much 



