354 On some Coml'matiom of Platinn. 



presence of water in tliu dry su'pii-ite of platiiia, yet thev 

 seem to show that, if it coniain any, the quantitv must be 

 extremely small. This idea may derive adchtional stienglh 

 from soiTie probable arguments fumishtd liy the agency of 

 heat on it, and from the restdts of i(s decomposition in 

 close vessels over dry mercury. — Thus, when the sulphate 

 in its driest state, after being exposed for a considerable 

 time to a heat just below redness, is suffered to remain for 

 a moment in contact with the cool atmosphere ; on heating 

 it again, copious vapours are evolved, and these vapours 

 seein to afford a good indication of the presence of moisture. 

 The fuming acid loses this pe-uliar property bv the smallest 

 quantity of water, and the gas obiainctl holds some of this 

 acid in mechanical suspension. When a bit of paper in its 

 common state of dryness is let up into the gas, a dense 

 white cloud is iiT^tmtly produced. — It is not difficult to 

 separate water from other meiallic sulphates, as those 

 of copper, zinc, iron, &:c. ; and there seems to be no 

 improbability in the idea that it may be separated from the 

 sulphate of plaiina, though the relations of the other sul- 

 phates to water, seem to be very different from that of the 

 sulphate c.f platiua. 



The three preceding experiinents were all made with 

 equal care, yet they do not appear to merit the same degree 

 of confidence. I shall venture to deduce the composition of 

 the sulphate from the two first ex|ierimcnts, as they very 

 nearly agree. But independent of this circumstance, their 

 near coincidence with results derived from the analyse;? of 

 the fixed alkaline sulphates of platina, and with the rule 

 given by Pr<-)fessor Berzelius relative to the constitution of 

 naetallic sulphates, are obvious reasons for the choice. •• 



By calculations, these experiments will be found to fur- 

 nish the following results for 100 grains of dry sulphat? 

 of platina. 



Pljtina. Oxv^ene. Sulphuric acid. 



Experiment 1. — Qb-'id + S-Ql + 26-37 



. r 2.— (]5'67 + 8-12 + 26-21 



Now taking the mean of these experiments, 100 grains 



of dry sulphate of platina will be composed of 



63-63 platina '^ f • i c i ,- -o ,^ 



- „, '^ ; oxide ot platina 73*70 



8-0fc» oxvgcne i i i j \.c \^ 



26-29 sulplturicacid >or of< ^^''P'^"'""^ ^^''^ J^ 



T^ J I '"^-'^^ 



Jvfow the sulphate of platina may be presumed to contain 



the 



