On defm'ile Proportions. 277 



\\sa\ been distilled over, I ignited the mass, and as soon as 

 the gas in the bulb of the reiort had lost its yellow colour, 

 I suffered the apparatus to cool. The mass had retained 

 the form of the plate of iron ; and when it was touched, 

 some pretty thick shining scales fell off from the iron on 

 which the sulphur had not acted. These scales had a cry- 

 stalline tracture and a niet-illic appearance. In their entire 

 state ihey were not attracted by the magnet, but they be- 

 came maiinetic when jjuiveriscd. 



Two g^aaunes of these scales, in large and regular pieces, 

 were digested with aqua regia, till nothing remained un- 

 dissolved, and the solution was precipitated by muriate of 

 baryta. The precipitate afforded 538 gr. of ignited sul- 

 phate of barvta. 



According to the experiments above related, 100 parts of 

 sulphae ot baryta contain 34 of sulphur.c acid, and in this 

 13-795 of sulphur; so that 5-38 gr. give '742 of sulphur,^ 

 that is, 37-1 percent, of the weight of the sulphuret of 

 iron. (Mr. Hatchett, who has examined the magnetical 

 pvrites, makes it 36-9 : at the same time his mode of ana- 

 lysis, and the data assumed for his computations are such, 

 that I can otdy consider our agreentent, in this and the 

 following analvsis, as perfectly accidental.) 



The liquid to which the muriate of baryta had been added 

 was freed from the baryta by sulphuric acid, and then de- 

 composed by caustic ammonia, The oxide, after ignition, 

 weishcd 1-82 gr. which gives 1-26 of iron. Here then is 

 an excess of '002 gr. {one. thirtieth of a grain,] which may 

 have depended on the supposition of too great 3 proportion 

 of sulphur in the su!ph>iric acid, or perhaps on a slight in- 

 accuracy of the weights employed. If we compute the 

 quantity of sulphur from that of the iron, it will appear 

 that 100 parts of iron took \ip 58'73 of sulphur; so that 

 the sulphurci of iron at a mininmm consists of 

 Sulphur 37 58-73 



Iron ... 63 lOO'OO 



If on the contrary we deduce the proportions from the 

 quantity of sulphur dclermiii(-d, we shall have 58-88 of sul- 

 phur for 100 of iron, and 100 of the sulphuret will contain 

 37-1 of sulphur and 62-9 of iron. 



B. Snlplmret of Iron at a Maximum. 



In order to determine the proportions of this compoimd, 



1 reduced again stnne of the ycalcs to a fine powder, mixed 



them with tmely pounded sulphur, and distilled the mixture 



in a small glass retort with a very gentle beat, as long a^ 



S3 mf 



