300 



Mr. Porrett on Ferro-chyazate of Potash, [Oct. 



Iron, 17-5. 



With Sulphur, 20. 



Protosulphuret, or Magneti 



Pyrites. 



2 Iron 35 6375 100 



1 Sulphur . . 20 3625 57 



55 10000 157 



Deutosulphuret. 



S Iron 52-5 57 100 



2 Sulphur... 40-0 43 76 



92-5 100 176 



Tritosulphuret. 



4 Iron 70 54 100 



With Oxygen, 10. 



With Chlorine, 45. 



Protoxide, or Black Oxide 

 (magnetic). 



2 Iron 35 7S 100-0 



1 Oxygen ... 10 22 28-5 



45 100 12S-5 



Deutoxide (Gay-Lussnc's) 

 {slightly magnetic). 



3 Iron 52-5 72-5 100 



2 Oxygen.. 200 27-5 3S 



72-5 1000 138 



Tritoxide, or Red Oxide. * 



4 Iron 70 70 100 



Protochloride. 



2 Iron 35 43-75 100-0 



I Chlorine.. 45 5625 128-7 



80 100-00 228-7 



,No corresponding chloride 

 known. 



3 Sulphur 60 46 86B Oxygen 30 30 43 



130 100 186 



Persulphurct,or Cubic Pyrites. 



1 Iron. .. 17-5 46-5 1000 

 1 Sulphur 20-0 53-5 114-2 



37-5 100-0 214-2 



100 100 143 



So corresponding oxide 

 known. 



Perchlnride. 

 Iron.... 70 34-14 10000 

 Chlorine 135 65-86 192-85 



205 100-00 292-85 



No corresponding chloride 

 known. 



In the first column of the above table, I have introduced two 

 sulphurets not hitherto admitted by chemists, the existence of 

 which it is, however, easy to infer from Proust's experiments, 

 recorded in his paper on the Native and Artificial Sulphurets of 

 Iron, a translation of which may be seen in the first volume of 

 the octavo edition of Nicholson's Philosophical Journal. He 

 distilled 400 gr. of fine cubic crystals of native persulphuret, and 

 separated from it 75 gr. of sulphur : there remained a sulphuret 

 weighing 322 gr. : hence 100 gr. would have become 81 gr. 

 Now as 100 persulphuret contain 46-5 of iron, these 81 gr. must 

 have contained the same quantity of that metal combined with 

 34-5 of sulphur; but as 46-5 is to 34*5, so is 57-4 to 42-6, which 

 agrees very closely with the composition assigned in the table to 

 the deutosulphuret. 



In another experiment described by Proust, he succeeded by 

 very cautiously applying a heat below redness to a mixture of 

 protosulphuret and sulphur in making the former take up half as 

 much sulphur again as it was previously combined with. Now on 

 referring to the table, it will be immediately obvious that he 

 must have formed the tritosulphuret which with 100 parts of iron 



* From HaDy's Experiments on Double Magnetism, it would seem that even the 

 red oxide retains some magnetic influence. 



