1820.] Mr. Ritchie on the Evaporation of Spirits. 215 



contains no new metal, serves to enrich mineralogy. According 

 to the analysis of M. Stromeyer, 100 parts of this ore are com- 

 posed of the following constituents : 



Nickel 16-2390 



Cobalt, with some manganese 4-2.5o7 



Iron 11-1238 



Copper 0-7375 



Lead 0-5267 



Antimony Trace 



Arsenic 56-2015 



Sulphm- 10-7137 



99-7979 



It is probable from this result, that in the Hungarian ore the 

 nickel and cobalt, together with a portion of the iron, are united 

 to the arsenic ; while, on the other hand, the manganese, cop- 

 per, lead, antimony, and the rest of the iron, exist in the state 

 of sulphurets. The considerable proportion of iron and sulphur 

 renders it not unlikely that the arseniurets, as well as the other 

 sulphurets, are held in solution together in the sulphuret of iron. 

 Of course, if we regard only the nature of the mineral, the 

 wodan-pyrites might with propriety be denominated iron pi/rites, 

 and it approaches nearest to the glanz nickel of Prof. Pfatf. 



As to the arseniuret of nickel in this ore. Prof. Stromeyer has 

 shov/n that it is very probable that the nickel is united w^ith 

 twice as much arsenic as in kupfernickel. 



Article VIII. 



On the Evaporation of Spirits of different Degrees of Strength. 

 By WiUiam Ritchie, A.M. of the Academy, Perth. 



(To Dr. Thomson.") 



SIR, 



It is a well-known fact that the evaporation of strong spirits 

 produces a greater degree of cold than the evaporation of weak 

 spirits or water ; but, as far as I recollect, it has not been stated 

 by any author that there exists a uniform ratio between the 

 induced cold and the strength of the evaporating spirits. If yovl; 

 consider the following theorem worthy of a place in your Annals 

 of Phihsophi/ you will much oblige. Sir, 



Your obedient servant, 



William Ritchie. 



Theorem. — The degrees of cold induced by the evaporation of 

 spirits of different degrees of strength are proportional to the 



