274 On some Combinations ofPlatina. 



were made at the request of Sir H. Davy, and which he has 

 noticed in his " Elements of Chemical Philosophy," p. 4.51, 

 I obtained only 18-5 percent, of chlorine. I have since 

 found that the substance then examined, was not platinana 

 in a pure state, hui a mixed compound, which of course 

 could not furnish correct results. 



Experiment 1. — 15 grains of platinana were heated to 

 redness in a small luud glass retort : wiien no more gas 

 could be expelled, the retort was suffered to cool, and the 

 results examined. The gas obtained amounted to three 

 cubical inches, and was chlorine: the remainder was absorbed 

 by the water during the process : it had a yellowish-greeii 

 colour, was absorbed on bein<>" agitated in water, and had 

 the precise odour of chlorine. The platina was in its me- 

 tallic state, and weighed 10- 7 grains : there was also a very 

 minute quantity of a brown substance in the neck of the 

 retort, which appeared to be a little of the compound ex- 

 pelled during the disengagement of the gas. 



From this experiment, 100 grains of platinana appear to 

 be composed of about 7 1*33 platina 

 2S-fl7 chlorine 



1(,0 



For 15 : 10-7 : : 100 : 71-33. 



But in this calculation no allowance is made for the small 

 quantity of the compound found in the neck of the retort. 

 Hence, there is reason to conclude that the quantity of 

 platina is here under-rated, which evidently appears to be 

 the case from the following experiments. 



Exfyerlment 2. — 10 grains of platinana mixed with 

 flowers of sulphur and heated to redness in a small retort, 

 afiforded sulphurane, and sulphuret of platina, which, when 

 reduced at a red heat in a platina crucible, furnished 7 "25 

 grains of platina. 



From this experiment it would appear that 100 grains of 

 platinana contain 72"5 platina 

 27'5 chlorine 



100 

 For 10 : 7-25 : : 100 : 725. 



JE^xperiment 3. — 10 grains of platinana exposed to a red 

 licat in a ))latin3 crucible were entirely decompounded, and 

 7*25 grains of platina were obtained. 



This experiment |)reciselv agrees with the preceding one. 



'Experiment 4. — 10 grams of platinana which had been 



exposed to the atmosphere for about 10 days were decon)- 



pounded 



